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Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

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New submissions for Mon, 19 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 3papers

Betelgeuse: a Review

Authors: J. Craig Wheeler, Emmanouil Chatzopoulos
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.09449
Pdf link: https://arxiv.org/pdf/2306.09449
Abstract
Betelgeuse has fascinated people since they first looked at the sky. Here we present a contemporary summary of the observations and theory that lead to our understanding of Betelgeuse as a massive red supergiant doomed to collapse and explosion. At only ~200 parsecs from Earth, Betelgeuse can be spatially resolved yet uncertainties in its distance remain a critical impediment to deeper understanding. The surface of Betelgeuse is rent with a complex structure as deep convective eddies arise to the surface affecting most of its measured physical properties. Determination of the equatorial rotation velocity is critical since some current estimates indicate that Betelgeuse is rotating anomalously rapidly, a property that cannot be explained by single-star evolutionary models. Betelgeuse is also moving through space at relatively high velocity that indicates that it received a boost, likely via collective interaction with other stars in its birth cluster. A bow shock and other structure in the direction of the star's motion suggest that it has affected the organization of the circumstellar and interstellar medium. Betelgeuse varies in brightness on a variety of time scales with 200, 400 and 2000 days being prominent. Betelgeuse is probable to have been born in a binary system, and the high space velocity and apparent rotation have been related to binary star evolution. One possibility is that Betelgeuse underwent common envelope evolution culminating in a final merger with the core of a massive primary. Such merger models have been invoked to account for the anomalous rotation velocity. Betelgeuse underwent a Great Dimming in 2020 that received widespread attention. Explanations have focused on large cool spots on the surface and the expulsion of a cloud of dust that obscured the surface. We sketch the nature of the explosion to come and discuss perspectives for further research.

The Dark Neutral Medium is (Mostly) Molecular Hydrogen

Authors: Harvey Liszt, Maryvonne Gerin
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.09502
Pdf link: https://arxiv.org/pdf/2306.09502
Abstract
We acquired ALMA ground state absorption profiles of HCO+ and other molecules toward 33 extragalactic continuum sources seen toward the Galactic anticenter, deriving N(H2) = N(HCO+)/3x10^{-9}. We observed J=1-0 CO emission with the IRAM 30m in directions where HCO+ was newly detected. HCO+ absorption was detected in 28 of 33 new directions and CO emission along 19 of those 28. The 5 sightlines lacking detectable HCO+ have 3 times lower mean EBV and N(DNM). Binned in EBV, N(H2) and N(DNM) are strongly correlated and vary by factors of 50-100 over the observed range EBV~0.05-1 mag, while N(HI) varies by factors of only 2-3. On average N(DNM) and N(H2) are well matched, and detecting HCO+ absorption adds little/no H2 in excess of the previously inferred DNM. There are 5 cases where 2N(H2) < N(DNM)/2 indicates saturation of the HI emission. For sightlines with \WCO > 1 K-\kms the CO-H2 conversion factor N(H2)/\WCO\ = 2-3x10^{20}\pcc/K-\kms is higher than derived from studies of resolved clouds in gamma-rays. Our work sampled primarily atomic gas with a mean H2 fraction ~1/3, but the DNM is almost entirely molecular. CO fulfills its role as an H2 tracer when its emission is strong, but large-scale CO surveys are not sensitive to H2 columns associated with typical values N(DNM) = 2-6x10^{20}\pcc. Lower \XCO\ values from $\gamma$-ray studies arise in part from different definitions and usage. Sightlines with \WCO\ \ge 1 K-\kms\ represent 2/3 of the H2 detected in HCO+ and detecting 90% of the H2 would require detecting CO at levels \WCO~0.2-0.3 K-\kms For full abstract see the paper

Astrophysical Uncertainties in the Gravitational-Wave Background from Stellar-Mass Compact Binary Mergers

Authors: Leonard Lehoucq, Irina Dvorkin, Rahul Srinivasan, Clement Pellouin, Astrid Lamberts
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.09861
Pdf link: https://arxiv.org/pdf/2306.09861
Abstract
We investigate the Stochastic Gravitational Wave Background (SGWB) produced by merging binary black holes (BBHs) and binary neutron stars (BNSs) in the frequency ranges of LIGO/Virgo/Kagra and LISA. We develop three analytical models, that are calibrated to the measured local merger rates, and complement them with three population synthesis models based on the COSMIC code. We discuss the uncertainties, focusing on the impact of the BBH mass distribution, the effect of the metallicity of the progenitor stars and the time delay distribution between star formation and compact binary merger. We also explore the effect of uncertainties in binary stellar evolution on the background. For BBHs, our analytical models predict $\Omega_{GW}$ in the range $[4.10^{-10}-1.10^{-9}]$ (25 Hz) and $[1.10^{-12}-4.10^{-12}]$ (3 mHz), and between $[2.10^{-10}-2.10^{-9}]$ (25 Hz) and $[7.10^{-13}- 7.10^{-12}]$ (3 mHz) for our population synthesis models. This background is unlikely to be detected during the LIGO/Virgo/Kagra O4 run, but could be detectable with LISA. We predict about 10 BBH and no BNS mergers that could be individually detectable by LISA for a period of observation of 4 years. Our study provides new insights into the population of compact binaries and the main sources of uncertainty in the astrophysical SGWB.

by olozhika (Xing Yuchen).

2023-06-20

New submissions for Wed, 28 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

阅读 Usage.md了解如何使用此repo实现个性化的Arxiv论文推送
See Usage.md for instructions on how to personalize the repo.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 4papers

Gravitational Wave Detection with Relative Astrometry using Roman's Galactic Bulge Time Domain Survey

Authors: Kris Pardo, Tzu-Ching Chang, Olivier Doré, Yijun Wang
Subjects: Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2306.14968
Pdf link: https://arxiv.org/pdf/2306.14968
Abstract
Gravitational waves (GWs) are a new avenue of observing our Universe. So far, we have seen them in the ~10-100 Hz range, and there are hints that we might soon detect them in the nanohertz regime. Multiple efforts are underway to access GWs across the frequency spectrum; however, parts of the frequency space are currently not covered by any planned or future observatories. Photometric surveys can bridge the microhertz gap in the spectrum between LISA and Pulsar Timing Arrays (PTAs) through relative astrometric measurements. Similar to PTA measurements, these astrometric measurements rely on the correlated spacetime distortions produced by gravitational waves at Earth, which induce coherent, apparent stellar position changes on the sky. To detect microhertz GWs with an imaging survey, a combination of high relative astrometric precision, a large number of observed stars, and a high cadence of exposures are needed. Roman's proposed core community survey, the Galactic Bulge Time Domain Survey (RGBTDS), would have all of these components. RGBTDS would be sensitive to GWs with frequencies ranging from $7.7\times 10^{-8}$ Hz to $5.6\times 10^{-4}$ Hz, which opens up a unique GW observing window for supermassive black hole binaries and their waveform evolution. We note that small changes to the survey could enhance Roman's sensitivity to GWs, making it possible to observe the GW background signal that PTAs have recently hinted at with an SNR $\sim$ 70.

A pre-explosion effervescent zone for the circumstellar material in SN 2023ixf

Authors: Noam Soker (Technion, Israel)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.15270
Pdf link: https://arxiv.org/pdf/2306.15270
Abstract
I present the effervescent zone model to account for the compact dense circumstellar material (CSM) around the progenitor of the core collapse supernova (CCSN) SN 2023ixf. The effervescent zone is composed of bound dense clumps that are lifted by stellar pulsation and envelope convection to distances of tens AUs, and then fall back. The dense clumps provide most of the compact CSM mass and exist alongside the regular (escaping) wind. I crudely estimate that for a compact CSM within ~30 AU that contains ~0.01 Mo, the density of each clump is >3000 times the density of the regular wind at the same radius and that the total volume filling factor of the clumps is several percent. The clumps might cover only a small fraction of the CCSN photosphere in the first days post-explosion, accounting for the lack of strong narrow absorption lines. The long-lived effervescent zone is compatible with no evidence for outbursts in the years prior to SN 2023ixf explosion and the large-amplitude pulsations of its progenitor, and it is an alternative to the CSM scenario of several-years-long high mass loss rate wind.

Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results

Authors: Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Shigehisa Takakuwa, Patrick Sheehan, Yuri Aikawa, Zhi-Yun Li, Leslie W. Looney, Jonathan P. Willians, Yusuke Aso, Rajeeb Sharma, Jinshi Sai (Insa Choi), Yoshihide Yamato, Jeong-Eun Lee, Kengo Tomida, Hsi-Wei Yen, Frankie J Encalada, Christian Flores, Sacha Gavino, Miyu Kido, Ilseung Han, Zhe-Yu Daniel Lin, Suchitra Narayanan, Nguyen Thi Phuong, Alejandro Santamaría-Miranda, Travis J. Thieme, Merel L. R. van 't Hoff, Itziar de Gregorio-Monsalvo, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Adele Plunkett, Kazuya Saigo, Shingo Hirano, Ka Ho Lam, Shoji Mori
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.15406
Pdf link: https://arxiv.org/pdf/2306.15406
Abstract
We present an overview of the Large Program, ``Early Planet Formation in Embedded Disks (eDisk)'', conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The ubiquitous detections of substructures, particularly rings and gaps, in protoplanetary disks around T Tauri stars raise the possibility that at least some planet formation may have already started during the embedded stages of star formation. In order to address exactly how and when planet formation is initiated, the program focuses on searching for substructures in disks around 12 Class 0 and 7 Class I protostars in nearby ($< $200 pc) star-forming regions through 1.3 mm continuum observations at a resolution of $\sim7$ au (0.04"). The initial results show that the continuum emission, mostly arising from dust disks around the sample protostars, has relatively few distinctive substructures, such as rings and spirals, in marked contrast to Class II disks. The dramatic difference may suggest that substructures quickly develop in disks when the systems evolve from protostars to Class II sources or alternatively that high optical depth of the continuum emission could obscure internal structures. Kinematic information obtained through CO isotopologue lines and other lines reveals the presence of Keplerian disks around protostars, providing us with crucial physical parameters, in particular, the dynamical mass of the central protostars. We describe the background of the eDisk program, the sample selection and their ALMA observations, the data reduction, and also highlight representative first-look results.

The short gamma-ray burst population in a quasi-universal jet scenario

Authors: O. S. Salafia, M. E. Ravasio, G. Ghirlanda, I. Mandel
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2306.15488
Pdf link: https://arxiv.org/pdf/2306.15488
Abstract
We describe a model of the short gamma-ray burst (SGRB) population under a quasi-universal jet' scenario in which jets can differ in their on-axis peak prompt emission luminosity $L_c$, but share a universal angular luminosity profile $\ell(\theta_v)=L(\theta_v)/L_c$ as a function of the viewing angle $\theta_v$. The model is fitted, through a Bayesian hierarchical approach inspired by gravitational wave (GW) population analyses, to 3 observed SGRB samples simultaneously: the Fermi/GBM sample of SGRBs with spectral information in the catalogue (367 events); a flux-complete sample of 16 Swift/BAT SGRBs also detected by GBM, with a measured redshift; and a sample of SGRBs with a binary neutron star (BNS) merger counterpart, which only includes GRB~170817A at present. The results favour a narrow jet core with half-opening angle $\theta_c=2.1_{-1.4}^{+2.4}$ deg (90\% credible intervals from our fiducial full sample' analysis) whose on-axis peak luminosity is distributed as $p(L_c) \propto L_c^{-A}$ with $A=3.2_{-0.4}^{+0.7}$ above a minimum luminosity $L_c^\star = 5_{-2}^{+11}\times 10^{51}$ erg s$^{-1}$. For $\theta_v>\theta_c$, the luminosity scales as a power law $\ell\propto \theta_v^{-\alpha_L}$ with $\alpha_L=4.7_{-1.4}^{+1.2}$, with no evidence for a break. While the model implies an intrinsic `Yonetoku' correlation between $L$ and the peak photon energy $E_p$, its slope is somewhat shallower $E_p\propto L^{0.4\pm 0.2}$ than the apparent one, and the normalization is offset towards larger $E_p$, due to selection effects. The implied local rate density of SGRBs is between about 100 up to several thousands of events per Gpc$^{3}$ yr, in line with the BNS merger rate density inferred from GW observations. Based on the model, we predict 0.2 to 1.3 joint GW+SGRB detections per year by the Advanced GW detector network and Fermi/GBM during the O4 observing run.

by olozhika (Xing Yuchen).

2023-06-28

New submissions for Tue, 2 May 23

Keyword: star formation

There is no result

Keyword: molecular cloud

There is no result

Keyword: N-PDF

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Keyword: cloud

Detection of monothioformic acid towards the solar-type protostar IRAS 16293-2422

Authors: Arijit Manna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00480
Pdf link: https://arxiv.org/pdf/2305.00480
Abstract
In the interstellar medium (ISM), the complex organic molecules that contain the thiol group ($-$SH) play an important role in the polymerization of amino acids. We look for SH-bearing molecules in the chemically rich solar-type protostar IRAS 16293-2422. After the extensive spectral analysis using the local thermodynamic equilibrium (LTE) model, we have detected the rotational emission lines of trans-isomer monothioformic acid (t-HC(O)SH) towards the IRAS 16293 B using the Atacama Large Millimeter/Submillimeter Array (ALMA). We did not observe any evidence of cis-isomer monothioformic acid (c-HC(O)SH) towards the IRAS 16293 B. The column density of t-HC(O)SH towards the IRAS 16293 B was (1.02$\pm$0.6)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 125$\pm$15 K. The fractional abundance of t-HC(O)SH with respect to H${2}$ towards the IRAS 16293 B is 8.50$\times$10$^{-11}$. The column density ratio of t-HC(O)SH/CH${3}$SH towards the IRAS 16293 B is 0.185. We compare our estimated abundance of t-HC(O)SH towards the IRAS 16293 B with the abundance of t-HC(O)SH towards the galactic center quiescent cloud G+0.693-0.027 and hot molecular core G31.41+0.31. After the comparison, we found that the abundance of t-HC(O)SH towards the IRAS 16293 B is several times of magnitude lower than G+0.693-0.027 and G31.41+0.31. We also discuss the possible formation mechanism of t-HC(O)SH in the ISM.

Joint Modelling of Dust Scattering and Thermal Emission: The Spider Complex

Authors: Jielai Zhang, Peter G Martin, Ryan Cloutier, Natalie Price-Jones, Roberto Abraham, Pieter van Dokkum, Allison Merritt
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.00756
Pdf link: https://arxiv.org/pdf/2305.00756
Abstract
Observations across the electromagnetic spectrum of radiative processes involving interstellar dust -- emission, extinction, and scattering -- are used to constrain the parameters of dust models and more directly to aid in foreground removal of dust for extragalactic and cosmology observations. The more complementary observations, the better. Here, we quantify the relationship between scattered light and thermal emission from dust in a diffuse (cirrus) intermediate latitude cloud, Spider, using data from the Dragonfly Telephoto Array and the Herschel Space Observatory. A challenge for optical observations of faint cirrus is accurate removal of a contaminating spatially varying sky background. We present a technique to analyse two images of the same cirrus field concurrently, correlating pixel values to capture the relationship and simultaneously fitting the sky background as a complex non-correlating additive component. For the Spider, we measure a $g-r$ color of 0.644$\pm 0.024$ and a visible wavelength to 250 $\mu$m intensity ratio of $10^{-3} \times (0.855 \pm0.025)$ and $10^{-3} \times (1.55\pm0.08)$ for $g$ and $r$-band respectively. We show how to use any dust model that matches the thermal dust emission to predict an upper limit to the amount of scattered light. The actual brightness of the cirrus will be fainter than this limit because of anisotropic scattering by the dust combined with anisotropy of the incident interstellar radiation field (ISRF). Using models of dust and the ISRF in the literature we illustrate that the predicted brightness is indeed lower, though not as faint as the observations indicate.

Keyword: interstellar medium

Detection of monothioformic acid towards the solar-type protostar IRAS 16293-2422

Authors: Arijit Manna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00480
Pdf link: https://arxiv.org/pdf/2305.00480
Abstract
In the interstellar medium (ISM), the complex organic molecules that contain the thiol group ($-$SH) play an important role in the polymerization of amino acids. We look for SH-bearing molecules in the chemically rich solar-type protostar IRAS 16293-2422. After the extensive spectral analysis using the local thermodynamic equilibrium (LTE) model, we have detected the rotational emission lines of trans-isomer monothioformic acid (t-HC(O)SH) towards the IRAS 16293 B using the Atacama Large Millimeter/Submillimeter Array (ALMA). We did not observe any evidence of cis-isomer monothioformic acid (c-HC(O)SH) towards the IRAS 16293 B. The column density of t-HC(O)SH towards the IRAS 16293 B was (1.02$\pm$0.6)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 125$\pm$15 K. The fractional abundance of t-HC(O)SH with respect to H${2}$ towards the IRAS 16293 B is 8.50$\times$10$^{-11}$. The column density ratio of t-HC(O)SH/CH${3}$SH towards the IRAS 16293 B is 0.185. We compare our estimated abundance of t-HC(O)SH towards the IRAS 16293 B with the abundance of t-HC(O)SH towards the galactic center quiescent cloud G+0.693-0.027 and hot molecular core G31.41+0.31. After the comparison, we found that the abundance of t-HC(O)SH towards the IRAS 16293 B is several times of magnitude lower than G+0.693-0.027 and G31.41+0.31. We also discuss the possible formation mechanism of t-HC(O)SH in the ISM.

Keyword: core

Recent Progress in Modelling the Macro- and Micro-Physics of Radio Jet Feedback in Galaxy Clusters

Authors: Martin A. Bourne, Hsiang-Yi Karen Yang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00019
Pdf link: https://arxiv.org/pdf/2305.00019
Abstract
Radio jets and the lobes they inflate are common in cool-core clusters and are expected to play a critical role in regulating the heating and cooling of the intracluster medium (ICM). This is an inherently multi-scale problem, and much effort has been made to understand the processes governing the inflation of lobes and their impact on the cluster, as well as the impact of the environment on the jet-ICM interaction, on both macro- and microphysical scales. Developments of new numerical techniques and improving computational resources have seen simulations of jet feedback in galaxy clusters become ever more sophisticated. This ranges from modelling ICM plasma physics processes such as the effects of magnetic fields, cosmic rays and viscosity to including jet feedback in cosmologically evolved cluster environments in which the ICM thermal and dynamic properties are shaped by large-scale structure formation. In this review, we discuss the progress made over the last ~decade in capturing both the macro- and microphysical processes in numerical simulations, highlighting both the current state of the field as well as open questions and potential ways in which these questions can be addressed in the future.

Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution -- Insights from the IRAM NOEMA large program CORE

Authors: Aida Ahmadi, H. Beuther, F. Bosco, C. Gieser, S. Suri, J. C. Mottram, R. Kuiper, Th. Henning, Á. Sánchez-Monge, H. Linz, R. E. Pudritz, D. Semenov, J. M. Winters, T. Möller, M. T. Beltrán, T. Csengeri, R. Galván-Madrid, K. G. Johnston, E. Keto, P. D. Klaassen, S. Leurini, S. N. Longmore, S. L. Lumsden, L. T. Maud, L. Moscadelli, A. Palau, T. Peters, S. E. Ragan, J. S. Urquhart, Q. Zhang, H. Zinnecker
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.00020
Pdf link: https://arxiv.org/pdf/2305.00020
Abstract
The fragmentation mode of high-mass molecular clumps and the accretion processes that form the most massive stars ($M\gtrsim 8M_\odot$) are still not well understood. To this end, we have undertaken a large observational program (CORE) making use of interferometric observations from the Northern Extended Millimetre Array (NOEMA) for a sample of 20 luminous ($L>10^4L_\odot$) protostellar objects in the 1.37 mm wavelength regime in both continuum and line emission, reaching $\sim$0.4" resolution (800 au at 2 kpc). Using the dense gas tracer CH$3$CN, we find velocity gradients across 13 cores perpendicular to the directions of bipolar molecular outflows, making them excellent disk candidates. Specific angular momentum ($j$) radial profiles are on average $\sim10^{-3}$ km /s pc and follow $j \propto r^{1.7}$, consistent with a poorly resolved rotating and infalling envelope/disk model. Fitting the velocity profiles with a Keplerian model, we find protostellar masses in the range of $\sim 10-25$ $M\odot$. Modelling the level population of CH$_3$CN lines, we present temperature maps and find median gas temperatures in the range $70-210$ K. We create Toomre $Q$ maps to study the stability of the disks and find almost all (11 of 13) disk candidates to be prone to fragmentation due to gravitational instabilities at the scales probed by our observations. In particular, disks with masses greater than $\sim10-20%$ of the mass of their host (proto)stars are Toomre unstable, and more luminous protostellar objects tend to have disks that are more massive and hence more prone to fragmentation. Our finings show that most disks around high-mass protostars are prone to disk fragmentation early in their formation due to their high disk to stellar mass ratio. This impacts the accretion evolution of high-mass protostars which will have significant implications for the formation of the most massive stars.

Machine Learning Uncovers the Universe's Hidden Gems: A Comprehensive Catalogue of CIV Absorption Lines in SDSS DR12

Authors: Reza Monadi, Ming-Feng Ho, Kathy L. Cooksey, Simeon Bird
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00023
Pdf link: https://arxiv.org/pdf/2305.00023
Abstract
We assemble the largest CIV absorption line catalogue to date, leveraging machine learning, specifically Gaussian processes, to remove the need for visual inspection for detecting CIV absorbers. The catalogue contains probabilities classifying the reliability of the absorption system within a quasar spectrum. Our training set was a sub-sample of DR7 spectra that had no detectable CIV absorption in a large visually inspected catalogue. We used Bayesian model selection to decide between our continuum model and our absorption-line models. Using a random hold-out sample of 1301 spectra from all of the 26,030 investigated spectra in DR7 CIV catalogue, we validated our pipeline and obtained an 87% classification performance score. We found good purity and completeness values, both ~80%, when a probability of ~95% is used as the threshold. Our pipeline obtained similar CIV redshifts and rest equivalent widths to our training set. Applying our algorithm to 185,425 selected quasar spectra from SDSS DR12, we produce a catalogue of 113,775 CIV doublets with at least 95% confidence. Our catalogue provides maximum a posteriori values and credible intervals for CIV redshift, column density, and Doppler velocity dispersion. We detect CIV absorption systems with a redshift range of 1.37 $!-!$ 5.1, including 33 systems with a redshift larger than 5 and 549 absorbers systems with a rest equivalent width greater than 2 A at more than 95% confidence. Our catalogue can be used to investigate the physical properties of the circumgalactic and intergalactic media.

Detection of monothioformic acid towards the solar-type protostar IRAS 16293-2422

Authors: Arijit Manna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00480
Pdf link: https://arxiv.org/pdf/2305.00480
Abstract
In the interstellar medium (ISM), the complex organic molecules that contain the thiol group ($-$SH) play an important role in the polymerization of amino acids. We look for SH-bearing molecules in the chemically rich solar-type protostar IRAS 16293-2422. After the extensive spectral analysis using the local thermodynamic equilibrium (LTE) model, we have detected the rotational emission lines of trans-isomer monothioformic acid (t-HC(O)SH) towards the IRAS 16293 B using the Atacama Large Millimeter/Submillimeter Array (ALMA). We did not observe any evidence of cis-isomer monothioformic acid (c-HC(O)SH) towards the IRAS 16293 B. The column density of t-HC(O)SH towards the IRAS 16293 B was (1.02$\pm$0.6)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 125$\pm$15 K. The fractional abundance of t-HC(O)SH with respect to H${2}$ towards the IRAS 16293 B is 8.50$\times$10$^{-11}$. The column density ratio of t-HC(O)SH/CH${3}$SH towards the IRAS 16293 B is 0.185. We compare our estimated abundance of t-HC(O)SH towards the IRAS 16293 B with the abundance of t-HC(O)SH towards the galactic center quiescent cloud G+0.693-0.027 and hot molecular core G31.41+0.31. After the comparison, we found that the abundance of t-HC(O)SH towards the IRAS 16293 B is several times of magnitude lower than G+0.693-0.027 and G31.41+0.31. We also discuss the possible formation mechanism of t-HC(O)SH in the ISM.

Small Planets Around Cool Dwarfs: Enhanced Formation Efficiency of Super-Earths around M dwarfs

Authors: Yayaati Chachan, Eve J. Lee
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.00803
Pdf link: https://arxiv.org/pdf/2305.00803
Abstract
Current measurements of planet population as a function of stellar mass show three seemingly contradictory signatures: close-in super-Earths are more prevalent around M dwarfs than FGK dwarfs; inner super-Earths are correlated with outer giants; and outer giants are less common around M dwarfs than FGK dwarfs. Here, we build a simple framework that combines the theory of pebble accretion with the measurements of dust masses in protoplanetary disks to reconcile all three observations. First, we show that cooler stars are more efficient at converting pebbles into planetary cores at short orbital periods. Second, when disks are massive enough to nucleate a heavy core at 5 AU, more than enough dust can drift in to assemble inner planets, establishing the correlation between inner planets and outer giants. Finally, while stars of varying masses are similarly capable of converting pebbles into cores at long orbital periods, hotter stars are much more likely to harbor more massive dust disks so that the giant planet occurrence rate rises around hotter stars. Our results are valid over a wide range of parameter space for a disk accretion rate that follows $\dot{M}\star \sim 10^{-8},M\odot,{\rm yr}^{-1}(M_\star/M_\odot)^2$. We predict a decline in mini-Neptune population (but not necessarily terrestrial planets) around stars lighter than $\sim 0.3-0.5 , M_\odot$. Cold giants ($\gtrsim$5 AU), if they exist, should remain correlated with inner planets even around lower mass stars.

Keyword: filament

There is no result

Keyword: atomic gas

There is no result

New submissions for Mon, 26 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 2papers

Young Star Clusters Dominate the Production of Detached Black Hole-Star Binaries

Authors: Ugo Niccolò Di Carlo, Poojan Agrawal, Carl L. Rodriguez, Katelyn Breivik
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.13121
Pdf link: https://arxiv.org/pdf/2306.13121
Abstract
The recent discovery of two detached black hole-star (BH-star) binaries from Gaia's third data release has sparkled interest in understanding the formation mechanisms of these systems. We investigate the formation of these systems by dynamical processes in young open star clusters (SCs) and via isolated binary (IB) evolution, using a combination of direct $N$-body models and population synthesis simulations. By comparing dynamical and isolated systems created using the same model of binary stellar evolution, we find that dynamical formation in SCs is nearly 40 times as efficient per unit of star formation at producing BH-star binaries compared to IB evolution. We expand this analysis to the full Milky Way (MW) using a FIRE-2 hydrodynamical simulation of a MW-mass galaxy. Even assuming that only $10%$ of star formation produces SCs with masses $> 1000,\mathrm{M_{\odot}}$, we find that the MW contains $\sim 2 \times 10^5$ BH-star systems, with approximately 4 out of every 5 systems being formed dynamically. Many of these dynamically-formed systems have larger orbital periods, eccentricities, and black hole masses than their isolated counterparts. For binaries older than 100 Myr, we show that any detectable system with $e\gtrsim0.5$ or $M_{\rm BH}\gtrsim 10,\mathrm{M_{\odot}}$ can only be formed through dynamical processes. Our MW model predicts between 61 and 210 such detections from the complete DR4 Gaia catalog, with the majority of systems being dynamically formed in massive and metal-rich SCs. Finally, we compare our populations to the recently discovered Gaia BH1 and Gaia BH2, and conclude that the dynamical scenario is the most favorable formation pathway for both systems.

The GUAPOS project:III. Characterization of the O- and N-bearing complex organic molecules content and search for chemical differentiation

Authors: C. Mininni, M.T. Beltrán, L. Colzi, V.M. Rivilla, F. Fontani, A. Lorenzani, Á. López-Gallifa, S. Viti, Á. Sánchez-Monge, P. Schilke, L. Testi
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.13563
Pdf link: https://arxiv.org/pdf/2306.13563
Abstract
The G31.41+0.31 Unbiased ALMA sPectral Observational Survey (GUAPOS) project targets the hot molecular core (HMC) G31.41+0.31 (G31), to unveil the complex chemistry of one of the most chemically rich high-mass star-forming regions outside the Galactic Center (GC). In the third paper of the project, we present a study of nine O-bearing (CH$_3$OH, $^{13}$CH$_3$OH, CH$_3^{18}$OH, CH$_3$CHO, CH$_3$OCH$_3$, CH$_3$COCH$_3$ , C$_2$H$_5$OH, aGg'-(CH$_2$OH)$_2$, and gGg'-(CH$_2$OH)$_2$) and six N-bearing (CH$_3$CN, $^{13}$CH$_3$CN, CH$_3^{13}$CN, C$_2$H$_3$CN, C$_2$H$_5$CN, and C$_2$H$_5^{13}$CN) complex organic molecules toward G31. The aim of this work is to characterize the abundances in one of the most chemically-rich hot molecular cores outside the GC and to search for a possible chemical segregation between O-bearing and N-bearing species in G31, which hosts four compact sources as seen with higher angular resolution data. Observations were carried out with the interferometer ALMA and covered the entire Band 3 from 84 to 116 GHz ($\sim 32$ GHz bandwidth) with an angular resolution of $1.2''$ ($\sim4400,\mathrm{au}$). The spectrum has been analyzed with the tool SLIM of MADCUBA to determine the physical parameters of the emitting gas. Moreover, we have analyzed the morphology of the emission of the molecular species. We have compared the abundances w.r.t methanol of COMs in G31 with other twenty-seven sources, including other hot molecular cores inside and outside the Galactic Center, hot corinos, shocked regions, envelopes around young stellar objects, and quiescent molecular clouds, and with chemical models. Different species peak at slightly different positions, and this, together with the different central velocities of the lines obtained from the spectral fitting, point to chemical differentiation of selected O-bearing species.

by olozhika (Xing Yuchen).

2023-06-26

New submissions for Thu, 4 May 23

Update Star Formation & Molecular Cloud papers at 2am UTC (10am Beijing time) every weekday.
forked from zhuhu00/Paper-Daily-Notice.
2023-05-04

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 5papers

The dynamics of debris streams from tidal disruption events: exact solutions, critical stream density, and hydrogen recombination

Authors: Eric R. Coughlin
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.01677
Pdf link: https://arxiv.org/pdf/2305.01677
Abstract
A star destroyed by a supermassive black hole (SMBH) in a tidal disruption event (TDE) is transformed into a filamentary structure known as a tidally disrupted stellar debris stream. We show that when ideal gas pressure dominates the thermodynamics of the stream, there is an exact solution to the hydrodynamics equations that describes the stream evolution and accounts for self-gravity, pressure, the dynamical expansion of the gas, and the transverse structure of the stream. We analyze the stability of this solution to cylindrically symmetric perturbations, and show that there is a critical stream density below which the stream is unstable and is not self-gravitating; this critical density is a factor of at least 40-50 smaller than the stream density in a TDE. Above this critical density the stream is overstable, self-gravity confines the stream, the oscillation period is exponentially long, and the growth rate of the overstability scales as $t^{1/6}$. The power-law growth and small power-law index of the overstability implies that the stream is effectively stable to cylindrically symmetric perturbations. We also use this solution to analyze the effects of hydrogen recombination, and suggest that even though recombination substantially increases the gas entropy, it is likely incapable of completely destroying the influence of self-gravity. We also show that the transient produced by recombination is far less luminous than previous estimates.

The Halo21 Absorption Modeling Challenge: Lessons From "Observing" Synthetic Circumgalactic Absorption Spectra

Authors: Zachary Hafen (1), Sameer (2, 3), Cameron Hummels (4), Jane Charlton (2), Nir Mandelker (5,6), Nastasha Wijers (7, 8), James Bullock (1), Yakov Faerman (9), Nicolas Lehner (3), Jonathan Stern (10) ((1) University of California, Irvine, (2) Pennsylvania State University, (3) University of Notre Dame, (4) California Institute of Technology, (5) Hebrew Institute of Jerusalem, (6) Kavli Institute for Theoretical Physics at UCSB, (7) Leiden Observatory, (8) CIERA, Northwestern University, (9) University of Washington, (10) Tel Aviv University)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.01842
Pdf link: https://arxiv.org/pdf/2305.01842
Abstract
In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using observational methods. We iteratively generated and analyzed three increasingly-complex data samples: ion column densities of isolated uniform clouds, mock spectra of 1--3 uniform clouds, and mock spectra of high-resolution turbulent mixing zones. We found that the observational estimates were accurate for both uniform cloud samples, with Z, T, and nH retrieved within 0.1 dex of the source value for >90% of absorption systems. In the turbulent-mixing scenario, the mass, temperature, and metallicity of the strongest absorption components were also retrieved with high accuracy. However, the underlying properties of the subdominant components were poorly constrained because the corresponding simulated gas contributed only weakly to the H I absorption profiles. On the other hand, including additional components beyond the dominant ones did improve the fit, consistent with the true existence of complex cloud structures in the source data.

Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets

Authors: Octavio M. Guilera, Pablo Benitez-Llambay, Marcelo M. Miller Bertolami, Martin E. Pessah
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.02140
Pdf link: https://arxiv.org/pdf/2305.02140
Abstract
Disk solids are critical in many planet formation processes, however, their effect on planet migration remains largely unexplored. Here we assess for the first time this important issue by building on the systematic measurements of dust torques on an embedded planet by Benitez-Llambay & Pessah (2018). Adopting standard models for the gaseous disk and its solid content, we quantify the impact of the dust torque for a wide range of conditions describing the disk/planet system. We show that the total torque can be positive and revert inward planet migration for planetary cores with $M_{\rm p} \lesssim 10 M_\oplus$. We compute formation tracks for low-mass embryos for conditions usually invoked when modeling planet formation processes. Our most important conclusion is that dust torques can have a significant impact on the migration and formation history of planetary embryos. The most important implications of our findings are: $\it{i})$ For nominal dust-to-gas mass ratios $\epsilon \simeq 0.01$, low-mass planets migrate outwards beyond the water ice-line if most of the mass in solids is in particles with Stokes numbers St $\simeq 0.1$. $\it{ii})$. For $\epsilon \gtrsim 0.02-0.05$, solids with small Stokes numbers, St $\simeq 0.01$, can play a dominant role if most of the mass is in those particles. $\it{iii})$ Dust torques have the potential to enable low-mass planetary cores formed in the inner disk to migrate outwards and act as the seed for massive planets at distances of tens of au.

Viscosity contrasts in the Venus mantle from tidal deformations

Authors: Christelle Saliby, Agnes Fienga, Arthur Briaud, Anthony Memin, Carianna Herrera
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.02278
Pdf link: https://arxiv.org/pdf/2305.02278
Abstract
The tidal deformations of a planet are often considered as markers of its inner structure. In this work, we use the tide excitations induced by the Sun on Venus for deciphering the nature of its internal layers. In using a Monte Carlo Random Exploration of the space of parameters describing the thickness, density and viscosity of 4 or 5 layer profiles, we were able to select models that can reproduce the observed mass, total moment of inertia, $k_2$ Love number and expected quality factor $Q$. Each model is assumed to have homogeneous layers with constant density, viscosity and rigidity. These models show significant contrasts in the viscosity between the upper mantle and the lower mantle. They also rather favor a S-free core and a slightly hotter lower mantle consistent with previous expectations.

Binary Formation in a 100 $μ$m-dark Massive Core

Authors: Shuo Kong, Héctor G. Arce, John J. Tobin, Yichen Zhang, María José Maureira, Kaitlin M. Kratter, Thushara G.S. Pillai
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.02286
Pdf link: https://arxiv.org/pdf/2305.02286
Abstract
We report high-resolution ALMA observations toward a massive protostellar core C1-Sa ($\sim$30 M$\odot$) in the Dragon Infrared Dark Cloud. At the resolution of 140 AU, the core fragments into two kernels (C1-Sa1 and C1-Sa2) with a projected separation of $\sim$1400 AU along the elongation of C1-Sa, consistent with a Jeans length scale of $\sim$1100 AU. Radiative transfer modeling using RADEX indicates that the protostellar kernel C1-Sa1 has a temperature of $\sim$75 K and a mass of 0.55 M$\odot$. C1-Sa1 also likely drives two bipolar outflows, one being parallel to the plane-of-the-sky. C1-Sa2 is not detected in line emission and does not show any outflow activity but exhibits ortho-H$_2$D$^+$ and N$2$D$^+$ emission in its vicinity, thus it is likely still starless. Assuming a 20 K temperature, C1-Sa2 has a mass of 1.6 M$\odot$. At a higher resolution of 96 AU, C1-Sa1 begins to show an irregular shape at the periphery, but no clear sign of multiple objects or disks. We suspect that C1-Sa1 hosts a tight binary with inclined disks and outflows. Currently, one member of the binary is actively accreting while the accretion in the other is significantly reduced. C1-Sa2 shows hints of fragmentation into two sub-kernels with similar masses, which requires further confirmation with higher sensitivity.

New submissions for Thu, 25 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 11papers

Type Ia Supernovae Induced by Primordial Black Holes from Dark First-Order Phase Transition

Authors: Pin-Jung Chen, Po-Yan Tseng
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2305.14399
Pdf link: https://arxiv.org/pdf/2305.14399
Abstract
A primordial black hole (PBH) with mass $10^{-15}\leq M_{\rm PBH}/M_{\odot}\leq 10^{-10}$ is currently beyond the sensitivity of both microlensing and black hole (BH) evaporation methods. A novel scenario has been proposed: When a PBH with mass $10^{-14}\leq M_{\rm PBH}/M_{\odot}\leq 10^{-11}$ transits through a white dwarf (WD) made up of carbon and oxygen, Bondi-Hoyle-Lyttleton (BHL) accretion in a reactive medium creates a shock wave, which generates direct detonation ignition in the WD core and then leads to thermonuclear supernovae (SNe Ia). The aim of this study is to impose constraints on the PBH to dark matter (DM) abundance fraction, $f_{\rm PBH}$, via comparing the SN Ia event rates between PBH hypotheses and observational data. For PBH fraction less than unity, we found the observed event rate prefers PBH mass region, $7.6\times 10^{-13}\leq M_{\rm PBH}/M_{\odot}\leq 6.1\times 10^{-12}$, under the Navarro-Frenk-White (NFW) profile. Meanwhile, the aforementioned PBH mass and abundance can be efficiently produced via a cosmological first-order phase transition (FOPT) in dark sector which associates with $\mathcal{O}({\rm MeV})$ energy scale and thus gives rise to complementary signals of stochastic gravitational waves (GWs) from $10^{-6}$ Hz to $10^{-5}$ Hz peak frequency which can be probed by future $\mu$Ares GW interferometer.

J0332-3557: A comprehensive metallicity analysis of a z~3.8 gravitationally lensed galaxy

Authors: Annalisa Citro, Danielle A. Berg, Dawn K. Erb, Matthew W. Auger, George D. Becker, Bethan L. James, Evan D. Skillman
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.14414
Pdf link: https://arxiv.org/pdf/2305.14414
Abstract
We provide one of the most comprehensive metallicity studies at z ~ 4 by analyzing the UV/optical HST photometry, and rest-frame VLT-FORS2 ultraviolet and VLT-XSHOOTER optical spectra of J0332-3557, a gravitationally lensed galaxy magnified by a factor of 20. With a 5{\sigma} detection of the auroral O III] {\lambda}1666 line, we are able to derive a direct gas metallicity estimate for our target. We find Zgas = 12 + log(O/H) = 8.26 +/- 0.06, which is compatible with an increasing of both the gas fraction and the outflow metal loading factor from z ~ 0 to z ~ 4. J0332 is the most metal-rich individual galaxy at z > 3.6 for which the C/O ratio has been measured. We derive a low log(C/O)= -1.02 +/- 0.2, which suggests that J0332 is in the early stages of ISM carbon enrichment driven mostly by massive stars. The low C/O also indicates that J0332 is characterized by a low star formation efficiency, higher yields of oxygen and longer burst duration. We find that the EW[C III]1906,9 is as low as ~ 3 {\AA}. The main drivers of the low EW[C III]1906,9 are the higher gas metallicity and the low C/O. J0332 is characterized by one diffuse and two more compact regions ~ 1 kpc in size. We find that the carbon emission mostly originates in the compact knots.

Separation of dust emission from the Cosmic Infrared Background in Herschel observations with Wavelet Phase Harmonics

Authors: Constant Auclair, Erwan Allys, François Boulanger, Matthieu Béthermin, Athanasia Gkogkou, Guilaine Lagache, Antoine Marchal, Marc-Antoine Miville-Deschênes, Bruno Régaldo-Saint Blancard, Pablo Richard
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.14419
Pdf link: https://arxiv.org/pdf/2305.14419
Abstract
The low brightness dust emission at high Galactic latitude is of interest to study the interplay between physical processes in shaping the structure of the interstellar medium (ISM), as well as to statistically characterize dust emission as a foreground to the Cosmic Microwave Background (CMB). Progress in this avenue of research have been hampered by the difficulty of separating the dust emission from the Cosmic Infrared Background (CIB). We demonstrate that dust and CIB may be effectively separated based on their different structure on the sky and use the separation to characterize the structure of diffuse dust emission on angular scales where CIB is a significant component in terms of power. We use scattering transform statistics, the Wavelet Phase Harmonics (WPH), to perform a statistical component separation using Herschel SPIRE observations. This component separation is done only from observational data using non-Gaussian properties as a lever arm, and is done at a single 250 microns frequency. This method, that we validate on mock data, gives us access to non-Gaussian statistics of the interstellar dust and an output dust map essentially free from CIB contamination. Our statistical modelling characterizes the non-Gaussian structure of the diffuse ISM down to the smallest scales observed by Herschel. We recover the power-law shape of the dust power spectrum up to a wavenumber of 2 arcmin$^{-1}$ where the dust signal represents 2 percent of the total power. The output dust map reveals coherent structures at the smallest scales which were hidden by the CIB anisotropies. It opens new observational perspectives on the formation of structure in the diffuse ISM which we discuss with reference to past work. We have succeeded to perform a statistical separation from observational data only at a single frequency by using non-Gaussian statistics.

From Dust to Nanodust: Resolving Circumstellar Dust from the Colliding-Wind Binary Wolf-Rayet (WR) 140

Authors: Ryan M. Lau, Jason Wang, Matthew J. Hankins, Thayne Currie, Vincent Deo, Izumi Endo, Olivier Guyon, Yinuo Han, Anthony P. Jones, Nemanja Jovanovic, Julien Lozi, Anthony F. J. Moffat, Takashi Onaka, Garreth Ruane, Andreas A. C. Sander, Samaporn Tinyanont, Peter G. Tuthill, Gerd Weigelt, Peredur M. Williams, Sebastien Vievard
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.14557
Pdf link: https://arxiv.org/pdf/2305.14557
Abstract
Wolf-Rayet (WR) 140 is the archetypal periodic dust-forming colliding-wind binary that hosts a carbon-rich WR (WC) star and an O-star companion with an orbital period of 7.93 years and an orbital eccentricity of 0.9. Throughout the past several decades, multiple dust-formation episodes from WR 140 have been observed that are linked to the binary orbit and occur near the time of periastron passage. Given its predictable dust-formation episodes, WR 140 presents an ideal astrophysical laboratory for investigating the formation and evolution of dust in the hostile environment around a massive binary system. In this paper, we present near- and mid-infrared (IR) spectroscopic and imaging observations of WR 140 with Subaru/SCExAO+CHARIS, Keck/NIRC2+PyWFS, and Subaru/COMICS taken between 2020 June and Sept that resolve the circumstellar dust emission linked to its most recent dust-formation episode in 2016 Dec. Our spectral energy distribution (SED) analysis of WR 140's resolved circumstellar dust emission reveals the presence of a hot ($T_\mathrm{d}\sim1000$ K) near-IR dust component that is co-spatial with the previously known and cooler ($T_\mathrm{d}\sim500$ K) mid-IR dust component composed of $300-500$ {\AA}-sized dust grains. We attribute the hot near-IR dust emission to the presence of nano-sized ("nanodust") grains and suggest they were formed from grain-grain collisions or the rotational disruption of the larger grain size population by radiative torques in the strong radiation field from the central binary. Lastly, we speculate on the astrophysical implications of nanodust formation around colliding-wind WC binaries, which may present an early source of carbonaceous nanodust in the interstellar medium.

Gas-phase formation of glycolonitrile in the interstellar medium

Authors: Luis Guerrero-Mendez, Anxo Lema-Saavedra, Elena Jimenez, Antonio Fernandez-Ramos, Emilio Martinez-Nunez
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Arxiv link: https://arxiv.org/abs/2305.14899
Pdf link: https://arxiv.org/pdf/2305.14899
Abstract
Our automated reaction discovery program, AutoMeKin, has been utilized to investigate the formation of glycolonitrile (HOCH${2}$CN) in the gas phase under the low temperatures of the interstellar medium (ISM). The feasibility of a proposed pathway depends on the absence of barriers above the energy of reactants and the availability of the suggested precursors in the ISM. Based on these criteria, several radical-radical reactions and a radical-molecule reaction have been identified as viable formation routes in the ISM. Among the radical-radical reactions, OH+CH${2}$CN appears to be the most relevant, considering the energy of the radicals and its ability to produce glycolonitrile in a single step. However, our analysis reveals that this reaction produces hydrogen isocyanide (HNC) and formaldehyde (CH${2}$O), with rate coefficients ranging from (7.3-11.5)$\times$10$^{-10}$ cm$^3$ molecule$^{-1}$ s$^{-1}$ across the temperature range of 10-150 K. This finding is particularly interesing given the persistently unexplained overabundance of hydrogen isocyanide in the ISM. Among the radical-molecule reactions investigated, the most promising one is OH+CH${2}$CNH, which forms glycolonitrile and atomic hydrogen with rate coefficients in the range (0.3-6.6)$\times$10$^{-10}$ cm$^3$ molecule$^{-1}$ s$^{-1}$ within the 10-150 K temperature range. Our calculations indicate that the formation of both hydrogen isocyanide and glycolonitrile is efficient under the harsh conditions of the ISM.

Exploring the effects of numerical methods and slope limiters in heliospheric modeling

Authors: Tinatin Baratashvili, Christine Verbeke, Rony Keppens, Stefaan Poedts
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Computational Physics (physics.comp-ph); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2305.14905
Pdf link: https://arxiv.org/pdf/2305.14905
Abstract
Coronal mass ejections (CMEs) are large eruptions close to the solar surface, where plasma is ejected outwards into space at large speeds. When directed towards Earth, they interfere with Earth's magnetic fields and cause strong geo-effective storms. In order to mitigate the potential damage, forecasting tools are implemented. Recently, a novel heliospheric modelling tool, Icarus, has been implemented, which exploits the open-source framework MPI-AMRVAC as its core MHD solver. This new model efficiently performs 3D MHD simulations of the solar wind and the evolution of interplanetary CMEs with the help of advanced techniques, such as adaptive mesh refinement and gradual radial grid stretching. The numerical methods applied in the simulations can have significant effects on the simulation results and on the efficiency of the model. In this study, the effect of different combinations of numerical schemes and slope limiters, for reconstructing edge-based variabes used in fluxes, is considered. We explore frequently exploited combinations from the available numerical schemes in MPI-AMRVAC: TVDLF, HLL and HLLC along with the slope limiters 'woodward', 'minmod', 'vanleer', and 'koren'. For analysis purposes, we selected one particular solar wind configuration and studied the influence on variables at 1 AU in the equatorial plane. The goal is to find the optimal combination to produce accurate results fast and in a robust way so that the model can be reliable for day-to-day use by space weather scientists. As a conclusion, the best result assessed with these two criteria is the combination of the TVDLF scheme with the 'woodward' limiter.

Implications of the Conformal Sound Speed Constraint on the Radius of PSR J0952-0607 within Rastall Gravity

Authors: Waleed El Hanafy, Adel Awad
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2305.14953
Pdf link: https://arxiv.org/pdf/2305.14953
Abstract
It has been shown that the nonminimal coupling between geometry and matter can provide models for massive compact Stars \citep{ElHanafy:2022kjl}, which are consistent with the conformal bound on the sound speed, $0\leq c_s^2 \leq c^2/3$, where the core density approaches a few times the nuclear saturation density. We impose the conformal sound speed upper bound constraint on Rastall's field equations of gravity, with Krori-Barua potentials in presence of an anisotropic fluid as a matter source, to estimate the radius of the most massive pulsar PSR J0952\textendash{0607} ever observed. For its measured mass $M = 2.35\pm 0.17, M_\odot$, we obtain a radius $R=14.087 \pm 1.0186$~km as inferred by the model. We investigate possible connection between Rastall garvity and MIT bag model with an EoS, $p_r(\rho) \approx c_s^2\left(\rho - \rho_\text{s}\right)$, in the radial direction, with $c_s=c/\sqrt{3}$ and a surface density $\rho_\text{s}$ slightly above the nuclear saturation density $\rho_\text{nuc}=2.7\times 10^{14}$~g/cm$^3$. The corresponding mass\textendash{radius} diagram is in agreement with our estimated value of the radius and with astrophysical observations of other pulsars at 68% C.L.

Complete X-ray census of Mdwarfs in the solar Neighborhood I. GJ 745 AB: Coronal-hole Stars in the 10 pc Sample

Authors: M. Caramazza, B. Stelzer, E. Magaudda, St. Raetz, M. Güdel, S. Orlando, K. Poppenhäger
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.14971
Pdf link: https://arxiv.org/pdf/2305.14971
Abstract
We have embarked in a systematic study of the X-ray emission in a volume-limited sample of M dwarf stars, in order to explore the full range of activity levels present in their coronae and, thus, to understand the conditions in their outer atmospheres and their possible impact on the circumstellar environment. We identify in a recent catalog of the Gaia objects within 10 pc from the Sun all the stars with spectral type between M0 and M4, and search systematically for X-ray measurements of this sample. To this end, we use both archival data (from ROSAT, XMM-Newton, and from the ROentgen Survey with an Imaging Telescope Array (eROSITA) onboard the Russian Spektrum-Roentgen-Gamma mission) and our own dedicated XMM-Newton observations. To make inferences on the properties of the M dwarf corona we compare the range of their observed X-ray emission levels to the flux radiated by the Sun from different types of magnetic structures: coronal holes, background corona, active regions and cores of active regions. At the current state of our project, with more than 90% of the 10pc M dwarf sample observed in X-rays, only GJ 745 A has no detection. With an upper limit luminosity of log Lx [erg/s] < 25.4 and an X-ray surface flux of log FX,SURF [erg/cm^2/s] < 3.6 GJ 745 A defines the lower boundary of the X-ray emission level of M dwarfs. Together with its companion GJ 745 B, GJ 745 A it is the only star in this volume-complete sample located in the range of FX,SURF that corresponds to the faintest solar coronal structures, the coronal holes. The ultra-low X-ray emission level of GJ 745 B (log Lx [erg/s] = 25.6 and log FX,SURF [erg/cm^2/s] = 3.8) is entirely attributed to flaring activity, indicating that, while its corona is dominated by coronal holes, at least one magnetically active structure is present and determines the total X-ray brightness and the coronal temperature of the star.

An Atypical Plateau-like Extreme-ultraviolet Late-phase Solar Flare Driven by the Non-radial Eruption of a Magnetic Flux Rope

Authors: Yuehong Chen, Yu Dai, Mingde Ding
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.14980
Pdf link: https://arxiv.org/pdf/2305.14980
Abstract
Recent observations in extreme-ultraviolet (EUV) wavelengths reveal an EUV late phase in some solar flares, which is characterized by a second peak in the warm coronal emissions (about 3 MK) occurring several tens of minutes to a few hours after the corresponding main flare peak. We aim to clarify the physical origin of an atypical plateau-like EUV late phase in an X1.8-class solar flare occurring on 2011 September 7 from active region (AR) 11283. We first characterize the plateau-like late phase using EUV Variability Experiment (EVE) full-disk integrated irradiance observations and Atmospheric Imaging Assembly (AIA) spatially-resolved imaging observations on board the Solar Dynamics Observatory (SDO). Then we perform a nonlinear force-free-field (NLFFF) extrapolation, from which a filament-hosting magnetic flux rope (MFR) is revealed. The eruption of the MFR is tracked both in the plane of the sky (POS) and along the line of sight (LOS) through visual inspection and spectral fitting, respectively. Finally, we carry out differential emission measure (DEM) analysis to explore the thermodynamics of the late-phase loops. The MFR shows a non-radial eruption from a fan-spine magnetic structure. The eruption of the MFR and its interaction with overlying arcades invoke multiple magnetic reconnections, which are responsible for the production of different groups of late-phase loops. Afterwards, the late-phase loops enter a long-lasting cooling stage, appearing sequentially in AIA passbands of decreasing response temperatures. Due to their different lengths, the different groups of late-phase loops cool down at different cooling rates, which makes their warm coronal emission peaks temporally separated from each other. Combing the emissions from all late-phase loops together, an elongated plateau-like late phase is formed.

The spatial distribution of an aromatic molecule, C6H5CN, in the cold dark cloud TMC-1

Authors: J. Cernicharo, B. Tercero, N. Marcelino, M. Agundez, P. de Vicente
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.15315
Pdf link: https://arxiv.org/pdf/2305.15315
Abstract
We present a highly sensitive 2D line survey of TMC-1 obtained with the Yebes 40m radio telescope in the Q-band (31.13-49.53 GHz). These maps cover a region of 320 arcsec x 320 arcsec centred on the position of the QUIJOTE line survey with a spatial sampling of 20 arcsec. The region covering 240 arcsec x 240 arcsec, where a longer integration time was used, shows a homogenous sensitivity of 2-4 mK across the band. We present in this work the first determination of the spatial extent of benzonitrile (C6H5CN), which follows that of cyanopolyynes rather well, but differs significantly from that of the radicals CnH and CnN. We definitively conclude that aromatic species in TMC-1 are formed from chemical reactions involving smaller species in the densest zones of the cloud.

Modeling the chemical enrichment history of the Bulge Fossil Fragment Terzan 5

Authors: Donatella Romano, Francesco R. Ferraro, Livia Origlia, Simon Portegies Zwart, Barbara Lanzoni, Chiara Crociati, Davide Massari, Emanuele Dalessandro, Alessio Mucciarelli, R. Michael Rich, Francesco Calura, Francesca Matteucci
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.15355
Pdf link: https://arxiv.org/pdf/2305.15355
Abstract
Terzan 5 is a heavily obscured stellar system located in the inner Galaxy. It has been postulated to be a stellar relic, a Bulge Fossil Fragment witnessing the complex history of the assembly of the Milky Way bulge. In this paper, we follow the chemical enrichment of a set of putative progenitors of Terzan 5 to assess whether the chemical properties of this cluster fit within a formation scenario in which it is the remnant of a primordial building block of the bulge. We can explain the metallicity distribution function and the runs of different element-to-iron abundance ratios as functions of [Fe/H] derived from optical-infrared spectroscopy of giant stars in Terzan 5, by assuming that the cluster experienced two major star formation bursts separated by a long quiescent phase. We further predict that the most metal-rich stars in Terzan 5 are moderately He-enhanced and a large spread of He abundances in the cluster, Y = 0.26-0.335. We conclude that current observations fit within a formation scenario in which Terzan 5 originated from a pristine, or slightly metal-enriched, gas clump about one order of magnitude more massive than its present-day mass. Losses of gas and stars played a major role in shaping Terzan 5 the way we see it now. The iron content of the youngest stellar population is better explained if the white dwarfs that give rise to type Ia supernovae (the main Fe factories) sink towards the cluster center, rather than being stripped by the strong tidal forces exerted by the Milky Way in the outer regions.

by olozhika (Xing Yuchen).

2023-05-25

New submissions for Wed, 24 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

Unveiling the time evolution of chemical abundances across the Milky Way disk with APOGEE

Authors: Bridget Ratcliffe, Ivan Minchev, Friedrich Anders, Sergey Khoperskov, Guillaume Guiglion, Tobias Buck, Katia Cunha, Anna Queiroz, Christian Nitschelm, Szabolcs Meszaros, Matthias Steinmetz, Roelof S. de Jong, Samir Nepal, Richard R. Lane, Jennifer Sobeck
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13378
Pdf link: https://arxiv.org/pdf/2305.13378
Abstract
Chemical abundances are an essential tool in untangling the Milky Way's enrichment history. However, the evolution of the interstellar medium abundance gradient with cosmic time is lost as a result of radial mixing processes. For the first time, we quantify the evolution of many observational abundances across the Galactic disk as a function of lookback time and birth radius, $R_\text{birth}$. Using an empirical approach, we derive $R_\text{birth}$ estimates for 145,447 APOGEE DR17 red giant disk stars, based solely on their ages and [Fe/H]. We explore the detailed evolution of 6 abundances (Mg, Ca ($\alpha$), Mn (iron-peak), Al, C (light), Ce (s-process)) across the Milky Way disk using 87,426 APOGEE DR17 red giant stars. We discover that the interstellar medium had three fluctuations in the metallicity gradient $\sim 9$, $\sim 6$, and $\sim4$ Gyr ago. The first coincides with the end of high-$\alpha$ sequence formation around the time of the Gaia-Sausage-Enceladus disruption, while the others are likely related to passages of the Sagittarius dwarf galaxy. A clear distinction is found between present-day observed radial gradients with age and the evolution with lookback time for both [X/Fe] and [X/H], resulting from the significant flattening and inversion in old populations due to radial migration. We find the [Fe/H]--[$\alpha$/Fe] bimodality is also seen as a separation in the $R_\text{birth}$--[X/Fe] plane for the light and $\alpha$-elements. Our results recover the chemical enrichment of the Galactic disk over the past 12 Gyr, providing tight constraints on Galactic disk chemical evolution models.

On the origin of the Galactic thin and thick discs, their abundance gradients and the diagnostic potential of their abundance ratios

Authors: Nikos Prantzos, Carlos Abia, Tianxiang Chen, Patrick de Laverny, Alejandra Recio-Blanco, E. Athanassoula, Lorenzo Roberti, Diego Vescovi, Marco Limongi, Alessandro Chieffi, Sergio Cristallo
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13431
Pdf link: https://arxiv.org/pdf/2305.13431
Abstract
Using a semi-analytical model of the evolution of the Milky Way, we show how secular evolution can create distinct overdensities in the phase space of various properties (e.g. age vs metallicity or abundance ratios vs age) corresponding to the thin and thick discs. In particular, we show how key properties of the Solar vicinity can be obtained by secular evolution, with no need for external or special events, like galaxy mergers or paucity in star formation. This concerns the long established double-branch behaviour of [alpha/Fe] vs metallicity and the recently found non-monotonic evolution of the stellar abundance gradient, evaluated at the birth radii of stars. We extend the discussion to other abundance ratios and we suggest a classification scheme, based on the nature of the corresponding yields (primary vs secondary or odd elements) and on the lifetimes of their sources (short-lived vs long-lived ones). The latter property is critical in determining the single- or double- branch behavior of an elementary abundance ratio in the Solar neighborhood. We underline the high diagnostic potential of this finding, which can help to separate clearly elements with sources evolving on different timescales and help determining the site of e.g. the r-process(es). We define the "abundance distance" between the thin and thick disc sequences as an important element for such a separation. We also show how the inside-out evolution of the Milky Way disc leads rather to a single-branch behavior in other disc regions.

Top-shaped Asteroids as Lens-shaped Bodies

Authors: Anthony R. Dobrovolskis, Jack J. Lissauer, Jose L. Alvarellos
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.13437
Pdf link: https://arxiv.org/pdf/2305.13437
Abstract
Several asteroids are known to be shaped like toy tops. This paper models Top-Shaped Asteroids (TSAs) as Homogeneous Symmetric Lenses (HSLs), and derives their rotational, self-gravitational, and total energies as functions of their mass, density, and angular momentum. Then we raise, test, and ultimately reject the hypothesis that TSAs take the shape of lowest total energy, subject to the constraint that they keep the same mass, density, and angular momentum, while remaining HSLs. Other processes must control the shapes of TSAs. For completeness, we also describe a Core-Mantle Model for TSAs, as well as an Inverted Core-Mantle Model, and derive their self-gravitational energies, along with their rotational energies. The gravitational potential at the center of an HSL then is derived.

Interstellar Bow Shocks around Fast Stars Passing through the Local Interstellar Medium

Authors: J. Michael Shull (1), S. R. Kulkarni (2) ((1) University of Colorado, (2) Caltech)
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.13449
Pdf link: https://arxiv.org/pdf/2305.13449
Abstract
Bow-shocks are produced in the local interstellar medium by the passage of fast stars from the Galactic thin-disk and thick-disk populations with velocities $V_* = $ 40-80 km/s. Stellar transits of local H I clouds occur every 3500-7000 yr on average and last between $10^4$ and $10^5$ yr. There could be 10-20 active bow shocks around low-mass stars inside clouds within 10-15 pc of the Sun. At local cloud distances of 3-10 pc, their turbulent wakes have transverse radial extents $R_{\rm wake} \approx$ 10-300 AU, angular sizes 10-100 arcsec, and Lyman-alpha surface brightnesses of 2-8 Rayleighs in gas with total hydrogen density $n_H \approx 0.1~{\rm cm}^{-3}$ and $V_* =$ 40-80 km/s. These transit wakes may cover an area fraction $f_A \approx (R_{\rm wake}/R_{\rm cl}) \approx 10^{-3}$ of local H I clouds and be detectable in IR (dust), UV (Lya, two-photon), or non-thermal radio emission. Turbulent heating in these wakes could produce the observed elevated rotational populations of H$_2$ ($J \geq 2$) and influence the endothermic formation of CH$^+$ in diffuse interstellar gas at $T > 10^3$ K.

FAST search for circumstellar atomic hydrogen. II. Is BD+303639 an interacting planetary nebula?

Authors: Xu-Jia Ouyang, Yong Zhang, Albert Zijlstra, Chuan-Peng Zhang, Jun-ichi Nakashima, Quentin A Parker
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13598
Pdf link: https://arxiv.org/pdf/2305.13598
Abstract
The young, compact, very high surface brightness but low excitation planetary nebula (PN) BD+303639 is one of the very few PNe that have been reported to exhibit the 21cm HI emission line. As part of a long-term programme to search for circumstellar atomic hydrogen, we observed the 21cm feature toward BD+303639 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Assuming a direct association between the PN and the detected HI emission, these new observations show that this surrounding emission is significantly more spatially extended than indicated by previous interferometric observations, and can be resolved into two velocity components. The estimated HI mass is larger than 100M_sun, invalidating an origin from the host star itself or its ejecta for the emitting material. We discuss the possibility that the extended HI emission stems from the interstellar medium (ISM) swept out over time by the stellar wind. Moreover, we report tentative detections of HI absorption features lying near and blueward of the systemic velocity of this PN, which are probably from a stalled asterosphere at the outer boundary of the expanding ionized region. The mass of the gas producing the HI absorption is insufficient to solve the so-called `PN missing mass problem'. We demonstrate the capability of FAST to investigate the interaction process between a PN and the surrounding ISM.

Investigating star formation activity in the Sh 2-61 H II region

Authors: Rakesh Pandey, Saurabh Sharma, Lokesh Dewangan, Aayushi Verma, Tapas Baug, Harmeen Kaur, Arpan Ghosh
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.13806
Pdf link: https://arxiv.org/pdf/2305.13806
Abstract
Using the multiwavelength data sets, we studied the star formation activity in H II region Sh 2-61 (hereafter S61). We identified a clustering in the region and estimated the membership using the Gaia proper motion data. The physical environment of S61 is inspected using infrared to radio wavelength images. We also determined the Lyman continuum flux associated with the H II region and found that the H II region is formed by at least two massive stars (S1 and S2). We also analyzed the 12CO (J =3-2) JCMT data of S61, and a shell structure accompanying three molecular clumps are observed towards S61. We found that the ionized gas in S61 is surrounded by dust and a molecular shell. Many young stellar objects and three molecular clumps are observed at the interface of the ionized gas and the surrounding gas. The pressure at the interface is higher than in a typical cool molecular cloud.

A partially stripped massive star in a Be binary at low metallicity: A missing link towards Be X-ray binaries and double neutron star mergers

Authors: V. Ramachandran, J. Klencki, A. A. C. Sander, D. Pauli, T. Shenar, L. M. Oskinova, W.-R. Hamann
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.14262
Pdf link: https://arxiv.org/pdf/2305.14262
Abstract
Standard binary evolutionary models predict a significant population of core helium-burning stars that lost their hydrogen-rich envelope after mass transfer via Roche-lobe overflow. However, there is a scarcity of observations of such stripped stars in the intermediate mass regime (~1.5 - 8$ M_{\odot}$), which are thought to be prominent progenitors of SN Ib/c. Especially at low metallicity, a significant fraction of these stars is expected to be only partially stripped, retaining a significant amount of hydrogen on their surfaces. For the first time, we discovered a partially stripped massive star in a binary with a Be-type companion located in the Small Magellanic Cloud (SMC) using a detailed spectroscopic analysis. The stripped-star nature of the primary is revealed by the extreme CNO abundance pattern and very high luminosity-to-mass ratio, which suggest that the primary is likely shell-hydrogen burning. Our target SMCSGS-FS 69 is the most luminous and most massive system among the known stripped star + Be binaries, with Mstripped ~3$ M_{\odot}$ and MBe ~17$ M_{\odot}$. Binary evolutionary tracks suggest an initial mass of Mini $\gtrsim 12 M_{\odot}$ for the stripped star and predict it to be in a transition phase towards a hot compact He star, which will eventually produce a stripped-envelope supernova. Our target marks the first representative of a so-far missing evolutionary stage in the formation pathway of Be X-ray binaries and double neutron star mergers.

by olozhika (Xing Yuchen).

2023-05-24

New submissions for Fri, 16 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 14papers

The photometric variability of massive stars due to gravity waves excited by core convection

Authors: Evan H. Anders, Daniel Lecoanet, Matteo Cantiello, Keaton J. Burns, Benjamin A. Hyatt, Emma Kaufman, Richard H.D. Townsend, Benjamin P. Brown, Geoffrey M. Vasil, Jeffrey S. Oishi, Adam S. Jermyn
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
Arxiv link: https://arxiv.org/abs/2306.08023
Pdf link: https://arxiv.org/pdf/2306.08023
Abstract
Massive stars die in catastrophic explosions, which seed the interstellar medium with heavy elements and produce neutron stars and black holes. Predictions of the explosion's character and the remnant mass depend on models of the star's evolutionary history. Models of massive star interiors can be empirically constrained by asteroseismic observations of gravity wave oscillations. Recent photometric observations reveal a ubiquitous red noise signal on massive main sequence stars; a hypothesized source of this noise is gravity waves driven by core convection. We present the first 3D simulations of massive star convection extending from the star's center to near its surface, with realistic stellar luminosities. Using these simulations, we make the first prediction of photometric variability due to convectively-driven gravity waves at the surfaces of massive stars, and find that gravity waves produce photometric variability of a lower amplitude and lower characteristic frequency than the observed red noise. We infer that the photometric signal of gravity waves excited by core convection is below the noise limit of current observations, so the red noise must be generated by an alternative process.

Old Data, New Forensics: The First Second of SN 1987A Neutrino Emission

Authors: Shirley Weishi Li, John F. Beacom, Luke F. Roberts, Francesco Capozzi
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.08024
Pdf link: https://arxiv.org/pdf/2306.08024
Abstract
The next Milky Way supernova will be an epochal event in multi-messenger astronomy, critical to tests of supernovae, neutrinos, and new physics. Realizing this potential depends on having realistic simulations of core collapse. We investigate the neutrino predictions of nearly all modern models (1-, 2-, and 3-d) over the first $\simeq$1 s, making the first detailed comparisons of these models to each other and to the SN 1987A neutrino data. Even with different methods and inputs, the models generally agree with each other. However, even considering the low neutrino counts, the models generally disagree with data. What can cause this? We show that neither neutrino oscillations nor different progenitor masses appear to be a sufficient solution. We outline urgently needed work.

The impact of baryonic potentials on the gravothermal evolution of self-interacting dark matter haloes

Authors: Yi-Ming Zhong, Daneng Yang, Hai-Bo Yu
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.08028
Pdf link: https://arxiv.org/pdf/2306.08028
Abstract
The presence of a central baryonic potential can have a significant impact on the gravothermal evolution of self-interacting dark matter (SIDM) haloes. We extend a semi-analytical fluid model to incorporate the influence of a static baryonic potential and calibrate it using controlled N-body simulations. We construct benchmark scenarios with varying baryon concentrations and different SIDM models, including constant and velocity-dependent self-interacting cross sections. The presence of the baryonic potential induces changes in SIDM halo properties, including central density, core size, and velocity dispersion, and it accelerates the halo's evolution in both expansion and collapse phases. Furthermore, we observe a quasi-universality in the gravothermal evolution of SIDM haloes with the baryonic potential, resembling a previously known feature in the absence of the baryons. By appropriately rescaling the physical quantities that characterize the SIDM haloes, the evolution of all our benchmark cases exhibits remarkable similarity. Our findings offer a framework for testing SIDM predictions using observations of galactic systems where baryons play a significant dynamical role.

Single-pulse analysis and average emission characteristics of PSR J1820-0427 from observations made with the MWA and uGMRT

Authors: Parul Janagal, Manoneeta Chakraborty, N. D. Ramesh Bhat, Samuel J. McSweeney, Susmita Sett
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.08050
Pdf link: https://arxiv.org/pdf/2306.08050
Abstract
We have studied the pulse-to-pulse variability in PSR J1820--0427 and its frequency dependence using high-quality, wide-band observations made from the upgraded Giant Metrewave Radio Telescope (uGMRT; 300-750 MHz) and the Murchison Widefield Array ($\sim$170-200 MHz). The low-frequency data reveal a previously unreported feature in the average profile (at 185 MHz) after accounting for the effects of temporal broadening arising from multi-path scattering due to the Interstellar Medium (ISM). We advance a new method for flux density calibration of beamformed data from the uGMRT and use it to measure the single pulse flux densities across the uGMRT band. Combined with previously published measurements, these flux densities are best fit with a power-law spectrum with a low-frequency turnover. We also use calibrated flux densities to explore the relationship between pulse-to-pulse variability and the spectral index of individual pulses. Our analysis reveals a large scatter in the single-pulse spectral indices and a general tendency for brighter pulses to show a steepening of the spectral index. We also examine the frequency-dependence of the pulse-fluence distribution and its relation to the Stochastic Growth Theory.

SPYGLASS. IV. New Stellar Survey of Recent Star Formation within 1 kpc

Authors: Ronan Kerr, Adam Kraus, Aaron Rizzuto
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.08150
Pdf link: https://arxiv.org/pdf/2306.08150
Abstract
Young stellar populations provide a powerful record that traces millions of years of star formation history in the solar neighborhood. Using a revised form of the SPYGLASS young star identification methodology, we produce an expanded census of nearby young stars (Age $<50$ Myr). We then use the HDBSCAN clustering algorithm to produce a new SPYGLASS Catalog of Young Associations (SCYA), which reveals 116 young associations within 1 kpc. More than 25% of these groups are largely new discoveries, as 20 are substantively different from any previous definition, and 10 have no equivalent in the literature. The new associations reveal a yet undiscovered demographic of small associations with little connection to larger structures. Some of the groups we identify are especially unique for their high transverse velocities, which can differ from the solar velocity by 30-50 km s$^{-1}$, and for their positions, which can reach up to 300 pc above the galactic plane. These features may suggest a unique origin, matching existing evidence of infalling gas parcels interacting with the disk ISM. Our clustering also suggests links between often-separated populations, hinting to direct structural connections between Orion Complex and Perseus OB2, and between the subregions of Vela. The $\sim$30 Myr old Cepheus-Hercules association is another emerging large-scale structure, with a size and population comparable to Sco-Cen. Cep-Her and other similarly-aged structures are also found clustered along extended structures perpendicular to known spiral arm structure, suggesting that arm-aligned star formation patterns have only recently become dominant in the solar neighborhood.

Radial and Non-Radial Oscillations of Inverted Hybrid Stars

Authors: Chen Zhang, Yudong Luo, Hong-bo Li, Lijing Shao, Renxin Xu
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2306.08234
Pdf link: https://arxiv.org/pdf/2306.08234
Abstract
We study the radial and non-radial oscillations of Cross stars (CrSs), i.e., stars with a quark matter crust and a hadronic matter core in an inverted order compared to conventional hybrid stars. We draw comparisons of their oscillation modes with those of neutron stars, quark stars, and conventional hybrid stars. We find that the stellar stability analysis from the fundamental mode of radial oscillations, and the $g$, $f$ modes of non-radial oscillations are quite similar to those of conventional hybrid stars. However, due to the inverted stellar structure, the first non-radial $p$ mode of CrSs behaves in an inverted way and sits in a higher frequency domain compared to that of conventional hybrid stars. These results provide a direct way to discriminate CrSs from other types of compact stars via gravitational-wave probes. Specifically, compact stars emitting $g$-mode gravitational waves within the $0.5$--$1$ kHz range should be CrSs or conventional hybrid stars rather than neutron stars or pure quark stars, and a further GW detection of the first $p$ mode above 8 kHz or an identification of a decreasing trend of frequencies versus star masses associated with it will help identify the compact object to be a CrS rather than a conventional hybrid star.

On the intensity ratio variation of the Si IV 1394/1403 Å lines during solar flares

Authors: Hao-Cheng Yu, J. Hong, M. D. Ding
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.08296
Pdf link: https://arxiv.org/pdf/2306.08296
Abstract
Context. The Si IV lines at 1394 \r{A} and 1403 \r{A} form in the solar atmosphere at a temperature of $\sim10^{4.8}$ K. They are usually considered optically thin, but their opacity can be enhanced during solar flares. Traditionally, the intensity ratio of these lines are used as an indicator of the optical thickness. However, observations have shown a wavelength-dependent intensity ratio profile $r(\Delta\lambda)$ of the the 1394 \r{A} to 1403 \r{A} lines. Aims. We aim to study the variation of the intensity ratio profile in solar flares and the physical reasons behind it. Method. The Si IV lines and their intensity ratio profiles are calculated from the one-dimensional radiative hydrodynamics flare model with non-thermal electron heating. Result. During flares, $r(\Delta\lambda)$ is smaller than 2 at the line core but larger than 2 at the line wings. We attribute the deviation of the ratio from 2 to two effects: the resonance scattering effect and the opacity effect. Resonance scattering increases the population ratio of the upper levels of the two lines, and as a result, increases $r(\Delta\lambda)$, in all wavelengths. The opacity effect decreases $r(\Delta\lambda)$, especially at the line core where the opacity is larger. These two effects compete with each other and cause the U-shape of $r(\Delta\lambda)$.

Astrochemical models of interstellar ices: History matters

Authors: A. Clément, A. Taillard, V. Wakelam, P. Gratier, J.-C. Loison, E. Dartois, F. Dulieu, J. A. Noble, M. Chabot
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.08346
Pdf link: https://arxiv.org/pdf/2306.08346
Abstract
Ice is ubiquitous in the interstellar medium. We model the formation of the main constituents of interstellar ices, including H2O, CO2 , CO, and CH3 OH. We strive to understand what physical or chemical parameters influence the final composition of the ice and how they benchmark to what has already been observed, with the aim of applying these models to the preparation and analysis of JWST observations. We used the Nautilus gas-grain model, which computes the gas and ice composition as a function of time for a set of physical conditions, starting from an initial gas phase composition. All important processes (gas-phase reactions, gas-grain interactions, and grain surface processes) are included and solved with the rate equation approximation. We first ran an astrochemical code for fixed conditions of temperature and density mapped in the cold core L429-C to benchmark the chemistry. One key parameter was revealed to be the dust temperature. When the dust temperature is higher than 12 K, CO2 will form efficiently at the expense of H2O, while at temperatures below 12 K, it will not form. Whatever hypothesis we assumed for the chemistry (within realistic conditions), the static simulations failed to reproduce the observed trends of interstellar ices in our target core. In a second step, we simulated the chemical evolution of parcels of gas undergoing different physical and chemical situations throughout the molecular cloud evolution and starting a few 1e7 yr prior to the core formation (dynamical simulations). Our dynamical simulations satisfactorily reproduce the main trends already observed for interstellar ices. Moreover, we predict that the apparent constant ratio of CO2/H2O observed to date is probably not true for regions of low AV , and that the history of the evolution of clouds plays an essential role, even prior to their formation.

Did Kepler-444 have a long-lived convective core?

Authors: Mark Lykke Winther, Víctor Aguirre Børsen-Koch, Jakob Lysgaard Rørsted, Amalie Stokholm, Kuldeep Verma
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.08430
Pdf link: https://arxiv.org/pdf/2306.08430
Abstract
With the greater power to infer the state of stellar interiors provided by asteroseismology, it has become possible to study the survival of initially convective cores within stars during their main-sequence evolution. Standard theories of stellar evolution predict that convective cores in sub-solar mass stars have lifetimes below 1 Gyr. However, a recent asteroseismic study of the star Kepler-444 concluded that the initial convective core had survived for nearly 8 Gyr. The goal of this paper is to study the convective-core evolution of Kepler-444 and to investigate its proposed longevity. We modify the input physics of stellar models to induce longer convective-core lifetimes and vary the associated parameter across a dense grid of evolutionary tracks. The observations of metallicity, effective temperature, mean density, and asteroseismic frequency ratios are fitted to the models using the BASTA pipeline. We explore different choices of constraints, from which a long convective-core lifetime is only recovered for a few specific combinations: mainly from the inclusion of potentially unreliable frequencies and/or excluding the covariances between the frequency ratios; while for the classical parameters, the derived luminosity has the largest influence. For all choices of observables, our analysis reliably constrains the convective-core lifetime of Kepler-444 to be short, with a median around 0.6 Gyr and a $1\sigma$ upper bound around 3.5 Gyr.

Vanadium oxide and a sharp onset of cold-trapping on a giant exoplanet

Authors: Stefan Pelletier, Björn Benneke, Mohamad Ali-Dib, Bibiana Prinoth, David Kasper, Andreas Seifahrt, Jacob L. Bean, Florian Debras, Baptiste Klein, Luc Bazinet, H. Jens Hoeijmakers, Aurora Y. Kesseli, Olivia Lim, Andres Carmona, Lorenzo Pino, Núria Casasayas-Barris, Thea Hood, Julian Stürmer
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.08739
Pdf link: https://arxiv.org/pdf/2306.08739
Abstract
The abundance of refractory elements in giant planets can provide key insights into their formation histories. Due to the Solar System giants' low temperatures, refractory elements condense below the cloud deck limiting sensing capabilities to only highly volatile elements. Recently, ultra-hot giant exoplanets have allowed for some refractory elements to be measured showing abundances broadly consistent with the solar nebula with titanium likely condensed out of the photosphere. Here we report precise abundance constraints of 14 major refractory elements on the ultra-hot giant planet WASP-76b that show distinct deviations from proto-solar, and a sharp onset in condensation temperature. In particular, we find nickel to be enriched, a possible sign of the accretion of a differentiated object's core during the planet's evolution. Elements with condensation temperatures below 1,550 K otherwise closely match those of the Sun before sharply transitioning to being strongly depleted above 1,550 K, well explained by nightside cold-trapping. We further unambiguously detect vanadium oxide on WASP-76b, a molecule long hypothesized to drive atmospheric thermal inversions, and also observe a global east-west asymmetry in its absorption signals. Overall, our findings indicate that giant planets have a mostly stellar-like refractory elemental content and suggest that temperature sequences of hot Jupiter spectra can show abrupt transitions wherein a mineral species is either present, or completely absent if a cold-trap exists below its condensation temperature.

ExoMDN: Rapid characterization of exoplanet interior structures with Mixture Density Networks

Authors: Philipp Baumeister, Nicola Tosi
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Machine Learning (cs.LG)
Arxiv link: https://arxiv.org/abs/2306.09002
Pdf link: https://arxiv.org/pdf/2306.09002
Abstract
Characterizing the interior structure of exoplanets is essential for understanding their diversity, formation, and evolution. As the interior of exoplanets is inaccessible to observations, an inverse problem must be solved, where numerical structure models need to conform to observable parameters such as mass and radius. This is a highly degenerate problem whose solution often relies on computationally-expensive and time-consuming inference methods such as Markov Chain Monte Carlo. We present ExoMDN, a machine-learning model for the interior characterization of exoplanets based on Mixture Density Networks (MDN). The model is trained on a large dataset of more than 5.6 million synthetic planets below 25 Earth masses consisting of an iron core, a silicate mantle, a water and high-pressure ice layer, and a H/He atmosphere. We employ log-ratio transformations to convert the interior structure data into a form that the MDN can easily handle. Given mass, radius, and equilibrium temperature, we show that ExoMDN can deliver a full posterior distribution of mass fractions and thicknesses of each planetary layer in under a second on a standard Intel i5 CPU. Observational uncertainties can be easily accounted for through repeated predictions from within the uncertainties. We use ExoMDN to characterize the interior of 22 confirmed exoplanets with mass and radius uncertainties below 10% and 5% respectively, including the well studied GJ 1214 b, GJ 486 b, and the TRAPPIST-1 planets. We discuss the inclusion of the fluid Love number $k_2$ as an additional (potential) observable, showing how it can significantly reduce the degeneracy of interior structures. Utilizing the fast predictions of ExoMDN, we show that measuring $k_2$ with an accuracy of 10% can constrain the thickness of core and mantle of an Earth analog to $\approx13%$ of the true values.

Exploring Stellar Cluster and Feedback-driven Star Formation in Galactic Mid-infrared Bubble [HKS2019] E70

Authors: Aayushi Verma, Saurabh Sharma, Kshitiz K. Mallick, Lokesh Dewangan, Devendra K. Ojha, Ram Kesh Yadav, Rakesh Pandey, Arpan Ghosh, Harmeen Kaur, Neelam Panwar, Tarak Chand
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.09031
Pdf link: https://arxiv.org/pdf/2306.09031
Abstract
We present a comprehensive analysis of the Galactic mid-infrared (MIR) bubble [HKS2019] E70 (E70) by adopting a multi-wavelength approach to understand the physical environment and star formation scenario around it. We identified a small (radius ~1.7 pc) stellar clustering inside the E70 bubble and its distance is estimated as 3.26 +/- 0.45 kpc. This cluster is embedded in the molecular cloud and hosts massive stars as well as young stellar objects (YSOs), suggesting active star formation in the region. The spectral type of the brightest star 'M1' of the E70 cluster is estimated as O9V and a circular ring/shell of gas and dust is found around it. The diffuse radio emission inside this ring/shell, the excess pressure exerted by the massive star 'M1' at the YSOs core, and the distribution of photo-dissociation regions (PDRs), a Class I YSO, and two ultra-compact (UC) H II regions on the rim of this ring/shell, clearly suggest positive feedback of the massive star 'M1' in the region. We also found a low-density shell-like structure in 12 CO(J=1-0) molecular emission along the perimeter of the E70 bubble. The velocity structure of the 12 CO emission suggests that the feedback from the massive star appears to have expelled the molecular material and subsequent swept-up material is what appears as the E70 bubble.

An overview of desorption parameters of Volatile and Complex Organic Molecules: A systematic dig on experimental literature

Authors: N.F.W. Ligterink, M. Minissale
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.09071
Pdf link: https://arxiv.org/pdf/2306.09071
Abstract
Many molecules observed in the interstellar medium are thought to result from thermal desorption of ices. Parameters such as desorption energy and pre-exponential frequency factor are essential to describe the desorption of molecules. Experimental determinations of these parameters are missing for many molecules, including those found in the interstellar medium. The objective of this work is to expand the number of molecules for which desorption parameters are available, by collecting and re-analysing experimental temperature programmed desorption data that are present in the literature. Transition State Theory (TST) is used in combination with the Redhead equation to determine desorption parameters. Experimental data and molecular constants (e.g., mass, moment of inertia) are collected and given as input. Using the Redhead-TST method, the desorption parameters for 133 molecules have been determined. The Redhead-TST method is found to provide reliable results that agree well with desorption parameters determined with more rigorous experimental methods. The importance of using accurately determined pre-exponential frequency factors to simulate desorption profiles is emphasised. The large amount of data allows to look for trends, the most important is the relationship log$_{10}$($\nu$) = 2.65ln($m$) + 8.07, where $\nu$ is the pre-exponential frequency factor and $m$ the mass of the molecule. The data collected in this work allow to model the thermal desorption of molecules and help understand changes in chemical and elemental composition of interstellar environments.

Decoding the age-chemical structure of the Milky Way disk: An application of Copulas and Elicitable Maps

Authors: Aarya A. Patil, Jo Bovy, Sebastian Jaimungal, Neige Frankel, Henry W. Leung
Subjects: Astrophysics of Galaxies (astro-ph.GA); Applications (stat.AP)
Arxiv link: https://arxiv.org/abs/2306.09319
Pdf link: https://arxiv.org/pdf/2306.09319
Abstract
In the Milky Way, the distribution of stars in the $[\alpha/\mathrm{Fe}]$ vs. $[\mathrm{Fe/H}]$ and $[\mathrm{Fe/H}]$ vs. age planes holds essential information about the history of star formation, accretion, and dynamical evolution of the Galactic disk. We investigate these planes by applying novel statistical methods called copulas and elicitable maps to the ages and abundances of red giants in the APOGEE survey. We find that the low- and high-$\alpha$ disk stars have a clean separation in copula space and use this to provide an automated separation of the $\alpha$ sequences using a purely statistical approach. This separation reveals that the high-$\alpha$ disk ends at the same [$\alpha$/Fe] and age at high $[\mathrm{Fe/H}]$ as the low-$[\mathrm{Fe/H}]$ start of the low-$\alpha$ disk, thus supporting a sequential formation scenario for the high- and low-$\alpha$ disks. We then combine copulas with elicitable maps to precisely obtain the correlation between stellar age $\tau$ and metallicity $[\mathrm{Fe/H}]$ conditional on Galactocentric radius $R$ and height $z$ in the range $0 < R < 20$ kpc and $|z| < 2$ kpc. The resulting trends in the age-metallicity correlation with radius, height, and [$\alpha$/Fe] demonstrate a $\approx 0$ correlation wherever kinematically-cold orbits dominate, while the naively-expected negative correlation is present where kinematically-hot orbits dominate. This is consistent with the effects of spiral-driven radial migration, which must be strong enough to completely flatten the age-metallicity structure of the low-$\alpha$ disk.

by olozhika (Xing Yuchen).

2023-06-16

New submissions for Fri, 5 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-05

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 9papers

Evidence of First Stars-enriched Gas in High-redshift Absorbers

Authors: A. Saccardi, S. Salvadori, V. D'Odorico, G. Cupani, M. Fumagalli, T. A. M. Berg, G. D. Becker, S. Ellison, S. Lopez
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.02346
Pdf link: https://arxiv.org/pdf/2305.02346
Abstract
The first stars were born from chemically pristine gas. They were likely massive, and thus they rapidly exploded as supernovae, enriching the surrounding gas with the first heavy elements. In the Local Group, the chemical signatures of the first stellar population were identified among low-mass, long-lived, very metal-poor ([Fe/H]<-2) stars, characterized by high abundances of carbon over iron ([C/Fe]>+0.7): the so-called carbon-enhanced metal-poor stars. Conversely, a similar carbon excess caused by first-star pollution was not found in dense neutral gas traced by absorption systems at different cosmic time. Here we present the detection of 14 very metal-poor, optically thick absorbers at redshift z~3-4. Among these, 3 are carbon-enhanced and reveal an overabundance with respect to Fe of all the analyzed chemical elements (O, Mg, Al, and Si). Their relative abundances show a distribution with respect to [Fe/H] that is in very good agreement with those observed in nearby very metal-poor stars. All the tests we performed support the idea that these C-rich absorbers preserve the chemical yields of the first stars. Our new findings suggest that the first-star signatures can survive in optically thick but relatively diffuse absorbers, which are not sufficiently dense to sustain star formation and hence are not dominated by the chemical products of normal stars.

Cool Cores in Clusters of Galaxies in the Dark Energy Survey

Authors: K. Graham, J. O'Donnell, M. M. Silverstein, O. Eiger, T. E. Jeltema, D. L. Hollowood, D. Cross, S. Everett, P. Giles, J. Jobel, D. Laubner, A. McDaniel, A. K. Romer, A. Swart, M. Aguena, S. Allam, O. Alves, D. Brooks, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, M. E. S. Pereira, J. De Vicente, S. Desai, J. P. Dietrich, P. Doel, I. Ferrero, J. Frieman, J. Garcia-Bellido, D. Gruen, R. A. Gruendl, S. R. Hinton, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, O. Lahav, J. L. Marshall, P. Melchior, J. Mena-Fernandez, F. Menanteau, R. Miquel, R. L. C. Ogando, A. Palmese, A. Pieres, A. A. Plazas Malagon, K. Reil, M. Rodriguez-Monroy, E. Sanchez, V. Scarpine, M. Schubnell, M. Smith, E. Suchyta, G. Tarle, C. To, N. Weaverdyck (for the DES Collaboration)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.02365
Pdf link: https://arxiv.org/pdf/2305.02365
Abstract
We search for the presence of cool cores in optically-selected galaxy clusters from the Dark Energy Survey (DES) and investigate their prevalence as a function of redshift and cluster richness. Clusters were selected from the redMaPPer analysis of three years of DES observations that have archival Chandra X-ray observations, giving a sample of 99 clusters with a redshift range of $0.11 < z < 0.87$ and a richness range of $25 < \lambda < 207$. Using the X-ray data, the core temperature was compared to the outer temperature to identify clusters where the core temperature is a factor of 0.7 or less than the outer temperature. We found a cool core fraction of approximately 20% with no significant trend in the cool core fraction with either redshift or richness.

Bimodal black-hole mass distribution and chirp masses of binary black-hole mergers

Authors: Fabian R.N. Schneider, Philipp Podsiadlowski, Eva Laplace
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.02380
Pdf link: https://arxiv.org/pdf/2305.02380
Abstract
In binary black-hole mergers from isolated binary-star evolution, both black holes are from progenitor stars that have lost their hydrogen-rich envelopes by binary mass transfer. Envelope stripping is known to affect the pre-supernova core structures of such binary-stripped stars and thereby their final fates and compact remnant masses. In this paper, we show that binary-stripped stars give rise to a bimodal black-hole mass spectrum with characteristic black-hole masses of about $9,\mathrm{M}\odot$ and $16,\mathrm{M}\odot$ across a large range of metallicities. The bimodality is linked to carbon and neon burning becoming neutrino-dominated, which results in interior structures that are difficult to explode and likely lead to black hole formation. The characteristic black-hole masses from binary-stripped stars have corresponding features in the chirp-mass distribution of binary black-hole mergers: peaks at about $8$ and $14,\mathrm{M}\odot$, and a dearth in between these masses. Current gravitational-wave observations of binary black-hole mergers show evidence for a gap at $10\text{--}12,\mathrm{M}\odot$ and peaks at $8$ and $14,\mathrm{M}_\odot$ in the chirp-mass distribution. These features are in agreement with our models of binary-stripped stars. In the future, they may be used to constrain the physics of late stellar evolution and supernova explosions, and may even help measure the cosmological expansion of the Universe.

Multiplicity Boost Of Transit Signal Classifiers: Validation of 69 New Exoplanets Using The Multiplicity Boost of ExoMiner

Authors: Hamed Valizadegan, Miguel J. S. Martinho, Jon M. Jenkins, Douglas A. Caldwell, Joseph D. Twicken, Stephen T. Bryson
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Artificial Intelligence (cs.AI); Machine Learning (cs.LG)
Arxiv link: https://arxiv.org/abs/2305.02470
Pdf link: https://arxiv.org/pdf/2305.02470
Abstract
Most existing exoplanets are discovered using validation techniques rather than being confirmed by complementary observations. These techniques generate a score that is typically the probability of the transit signal being an exoplanet (y(x)=exoplanet) given some information related to that signal (represented by x). Except for the validation technique in Rowe et al. (2014) that uses multiplicity information to generate these probability scores, the existing validation techniques ignore the multiplicity boost information. In this work, we introduce a framework with the following premise: given an existing transit signal vetter (classifier), improve its performance using multiplicity information. We apply this framework to several existing classifiers, which include vespa (Morton et al. 2016), Robovetter (Coughlin et al. 2017), AstroNet (Shallue & Vanderburg 2018), ExoNet (Ansdel et al. 2018), GPC and RFC (Armstrong et al. 2020), and ExoMiner (Valizadegan et al. 2022), to support our claim that this framework is able to improve the performance of a given classifier. We then use the proposed multiplicity boost framework for ExoMiner V1.2, which addresses some of the shortcomings of the original ExoMiner classifier (Valizadegan et al. 2022), and validate 69 new exoplanets for systems with multiple KOIs from the Kepler catalog.

Variability of Young Stellar Objects in the Perseus Molecular Cloud

Authors: Xiao-Long Wang, Min Fang, Gregory J. Herczeg, Yu Gao, Hai-Jun Tian, Xing-Yu Zhou, Hong-Xin Zhang, Xue-Peng Chen
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.02514
Pdf link: https://arxiv.org/pdf/2305.02514
Abstract
We present an analysis of 288 young stellar objects (YSOs) in the Perseus Molecular Cloud that have well defined $g$ and $r$-band lightcurves from the Zwicky Transient Facility. Of the 288 YSOs, 238 sources (83% of our working sample) are identified as variables based on the normalized peak-to-peak variability metric, with variability fraction of 92% for stars with disks and 77% for the diskless populations. These variables are classified into different categories using the quasiperiodicity ($Q$) and flux asymmetry ($M$) metrics. Fifty-three variables are classified as strictly periodic objects that are well phased and can be attributed to spot modulated stellar rotation. We also identify 22 bursters and 25 dippers, which can be attributed to accretion burst and variable extinction, respectively. YSOs with disks tend to have asymmetric and non-repeatable lightcurves, while the YSOs without disks tend to have (quasi)periodic lightcurves. The periodic variables have the steepest change in $g$ versus $g-r$, while bursters have much flatter changes than dippers in $g$ versus $g-r$. Periodic and quasiperiodic variables display the lowest variability amplitude. Simple models suggest that the variability amplitudes of periodic variables correspond to changes of the spot coverage of 30% to 40%, burster variables are attributed to accretion luminosity changes in the range of $L_{\rm acc}/L_{\star}=0.1-0.3$, and dippers are due to variable extinction with $A_{V}$ changes in the range of $0.5-1.3;$mag.

The Shape of Jupiter and Saturn Based on Atmospheric Dynamics, Radio Occultations and Gravity Measurements

Authors: Eli Galanti, Yohai Kaspi, Tristan Guillot
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.02647
Pdf link: https://arxiv.org/pdf/2305.02647
Abstract
The shape of the two gas giants, Jupiter and Saturn, is determined primarily by their rotation rate, and interior density distribution. It is also affected by their zonal winds, causing an anomaly of O(10 km) at low latitudes. However, uncertainties in the observed cloud-level wind and the polar radius, translate to an uncertainty in the shape with the same order of magnitude. The Juno (Jupiter) and Cassini (Saturn) missions gave unprecedented accurate gravity measurements, constraining better the uncertainty in the wind structure. Using an accurate shape calculation, and a joint optimization, given both gravity and radio-occultation measurements, we calculate the possible range of dynamical height for both planets. We find that for Saturn there is an excellent match to the radio-occultation measurements, while at Jupiter such a match is not achieved. This may point to deviations from a barotropic flow above the cloud level, which might be tested with the forthcoming radio-occultation measurements by Juno.

JWST constraints on the UV luminosity density at cosmic dawn: implications for 21-cm cosmology

Authors: Sultan Hassan, Christopher C. Lovell, Piero Madau, Marc Huertas-Company, Rachel S. Somerville, Blakesley Burkhart, Keri L. Dixon, Robert Feldmann, Tjitske K. Starkenburg, John F. Wu, Christian Kragh Jespersen, Joseph D. Gelfand, Ankita Bera
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.02703
Pdf link: https://arxiv.org/pdf/2305.02703
Abstract
An unprecedented array of new observational capabilities are starting to yield key constraints on models of the epoch of first light in the Universe. In this Letter we discuss the implications of the UV radiation background at cosmic dawn inferred by recent JWST observations for radio experiments aimed at detecting the redshifted 21-cm hyperfine transition of diffuse neutral hydrogen. Under the basic assumption that the 21-cm signal is activated by the Ly$\alpha$ photon field produced by metal-poor stellar systems, we show that a detection at the low frequencies of the EDGES experiment may be expected from a simple extrapolation of the declining UV luminosity density estimated at $z\lesssim 14$ by JWST early galaxy data. Our findings raise the intriguing possibility that a high star formation efficiency at early times may trigger the onset of intense Ly$\alpha$ emission at redshift $z\lesssim 18$ and produce a cosmic 21-cm absorption signal 200 Myr after the Big Bang.

Star Formation History of the Small Magellanic Cloud: the shell substructure

Authors: Joanna D. Sakowska, Noelia E. D. Noël, Tomás Ruiz-Lara, Carme Gallart
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.02755
Pdf link: https://arxiv.org/pdf/2305.02755
Abstract
We present the spatially resolved star formation history (SFH) of a shell-like structure located in the northeastern Small Magellanic Cloud (SMC). We quantitatively obtain the SFH using unprecedented deep photometric data (g~24 magnitude) from the SMASH survey and colour-magnitude diagram (CMD) fitting techniques. We consider, for the first time, the SMC's line-of-sight depth and its optical effects on the CMDs. The SFH presents higher accuracy when a line-of-sight depth of ~3 Kpc is simulated. We find young star formation enhancements at ~150 Myr, ~200 Myr, ~450 Myr, ~650 Myr, and ~1 Gyr. Comparing the shell's SFH with the Large Magellanic Cloud's (LMC) northern arm SFH we show strong evidence of synchronicity from at least the past ~2.8 Gyr and, possibly, the past ~3.5 Gyr. Our results place constraints on the orbital history of the Magellanic Clouds which, potentially, have implications on their dynamical mass estimates.

JWST NIRSpec spectroscopy of the triply-lensed $z = 10.17$ galaxy MACS0647$-$JD

Authors: Tiger Yu-Yang Hsiao, Abdurro'uf, Dan Coe, Rebecca L. Larson, Intae Jung, Matilde Mingozzi, Pratika Dayal, Nimisha Kumari, Vasily Kokorev, Anton Vikaeus, Gabriel Brammer, Lukas J. Furtak, Angela Adamo, Felipe Andrade-Santos, Jacqueline Antwi-Danso, Marusa Bradac, Larry D. Bradley, Tom Broadhurst, Adam C. Carnall, Christopher J. Conselice, Jose M. Diego, Megan Donahue, Jan J. Eldridge, Seiji Fujimoto, Alaina Henry, Svea Hernandez, Taylor A. Hutchison, Bethan L. James, Colin Norman, Hyunbae Park, Norbert Pirzkal, Marc Postman, Massimo Ricotti, Jane R. Rigby, Eros Vanzella, Brian Welch, Stephen M. Wilkins, Rogier A. Windhorst, Xinfeng Xu, Erik Zackrisson, Adi Zitrin
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.03042
Pdf link: https://arxiv.org/pdf/2305.03042
Abstract
We present JWST/NIRSpec prism spectroscopy of MACS0647-JD, the triply-lensed $z \sim 11$ candidate discovered in HST imaging and spatially resolved by JWST imaging into two components A and B. Spectroscopy of component A yields a spectroscopic redshift $z=10.17$ based on 7 detected emission lines: CIII] $\lambda\lambda$1907,1909, [OII] $\lambda$3727, [NeIII] $\lambda$3869, [NeIII] $\lambda$3968, H$\delta$ $\lambda$4101, H$\gamma$ $\lambda$4340, and [OIII] $\lambda$4363. These are the second-most distant detections of these emission lines to date, in a galaxy observed just 460 million years after the Big Bang. Based on observed and extrapolated line flux ratios we derive a gas-phase metallicity $Z =$ log(O/H) = $7.5 - 8.0$, or $(0.06 - 0.2)$ $Z_\odot$, ionization parameter log($U$) $\sim -1.9\pm0.2$, and an ionizing photon production efficiency ${\rm log}(\xi_{\rm ion})=25.2\pm0.2,$erg$^{-1}$ Hz. The spectrum has a softened Lyman-$\alpha$ break, evidence for a strong Ly$\alpha$ damping wing, suggesting that MACS0647-JD was unable to ionize its surroundings beyond its immediate vicinity ($R_{\text{HII}} \ll 1$ pMpc). The Ly$\alpha$ damping wing also suppresses the F150W photometry, explaining the slightly overestimated photometric redshift $z = 10.6 \pm 0.3$. MACS0647-JD has a stellar mass log($M/M_\odot$) = $8.1 \pm 0.3$, including $\sim$ 6$\times 10^7 M_\odot$ in component A, most of which formed recently (within $\sim$ 20 Myr) with a star formation rate $2\pm1 M_\odot$ / yr, all within an effective radius $70\pm24,$pc. The smaller component B ($r \sim 20$) pc is likely older ($\sim$100 Myr) with more dust ($A_V \sim 0.1$ mag), as found previously. Spectroscopy of a fainter companion galaxy C separated by a distance of \about\ 3$,$kpc reveals a Lyman break consistent with $z = 10.17$. MACS0647-JD is likely the most distant galaxy merger known.

New submissions for Mon, 5 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 11papers

A VLBI Proper Motion Analysis of the Recoiling Supermassive Black Hole Candidate Mrk 1018

Authors: Gregory Walsh, Sarah Burke-Spolaor, T. Joseph W. Lazio
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01036
Pdf link: https://arxiv.org/pdf/2306.01036
Abstract
Mrk 1018 is a nearby changing-look AGN that has oscillated between spectral Type 1.9 and Type 1 over a period of 40 years. Recently, a recoiling supermassive black hole (rSMBH) scenario has been proposed to explain the spectral and flux variability observed in this AGN. Detections of rSMBHs are important for understanding the processes by which SMBH binaries merge and how rSMBHs influence their galactic environment through feedback mechanisms. However, conclusive identification of any rSMBHs has remained elusive to date. In this paper, we present an analysis of 6.5 years of multi-frequency Very Long Baseline Array (VLBA) monitoring of Mrk 1018. We find that the radio emission is compact down to 2.4 pc, and displays flux density and spectral variability over the length of our campaign, typical of a flat spectrum radio core. We observe proper motion in RA of the radio core at -36.4 $\pm$ 8.6 $\mu$as yr$^{-1}$ (4.2$\sigma$), or $0.10c \pm 0.02c$ at the redshift of Mrk 1018. No significant proper motion is found in DEC (31.3 $\pm$ 25.1 $\mu$as yr$^{-1}$). We discuss possible physical mechanisms driving the proper motion, including a rSMBH. We conclude that the apparent velocity we observe of the VLBI radio core is too high to reconcile with theoretical predictions of rSMBH velocities and that the proper motion is most likely dominated by an unresolved, outflowing jet component. Future observations may yet reveal the true nature of Mrk 1018. However, our observations are not able to confirm it as a true rSMBH.

The Supersonic Project: Star Formation in Early Star Clusters without Dark Matter

Authors: William Lake, Smadar Naoz, Federico Marinacci, Blakesley Burkhart, Mark Vogelsberger, Claire E. Williams, Yeou S. Chiou, Gen Chiaki, Yurina Nakazato, Naoki Yoshida
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01047
Pdf link: https://arxiv.org/pdf/2306.01047
Abstract
The formation mechanism of globular clusters (GCs) has long been debated by astronomers. It was recently proposed that Supersonically Induced Gas Objects (SIGOs), which formed in the early Universe due to the supersonic relative motion of baryons and dark matter at recombination, could be the progenitors of early globular clusters. In order to become GCs, SIGOs must form stars relatively efficiently despite forming outside of dark matter halos. We investigate the potential for star formation in SIGOs using cosmological hydrodynamic simulations, including the aforementioned relative motions of baryons and dark matter, molecular hydrogen cooling in primordial gas clouds, and including explicit star formation. We find that SIGOs do form stars and that the nascent star clusters formed through this process are accreted by dark matter halos on short timescales (a few hundreds of Myr). Thus, SIGOs may be found as intact substructures within these halos, analogous to many present-day GCs. From this result, we conclude that SIGOs are capable of forming star clusters with similar properties to globular clusters in the early Universe and we discuss their detectablity by upcoming JWST surveys.

HI Absorption in Low-power Radio AGNs Detected by FAST

Authors: Qingzheng Yu, Taotao Fang, Junfeng Wang, Jianfeng Wu
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01050
Pdf link: https://arxiv.org/pdf/2306.01050
Abstract
We report the discovery of three HI absorbers toward low-power radio active galactic nuclei (AGNs) in a pilot HI absorption survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Compared to past studies, FAST observations have explored lower radio powers by $\sim$0.4 dex and detected these weakest absorbers at given redshifts. By comparing the gas properties and kinematics of sources along radio powers, we aim to explore the interplay between AGN and the surrounding interstellar medium (ISM). Compared to brighter sources at similar redshifts, our observations suggest a slightly lower detection rate of HI absorption lines ($\sim$$11.5%$) in low-power radio AGNs with $\text{log}(P_{\text{1.4 GHz}}/\text{W Hz}^{-1})=21.8-23.7$. The low-power sources with $\text{log}(P_{\text{1.4 GHz}}/\text{W Hz}^{-1})<23$ have a lower detection rate of $\sim$$6.7%$. Due to the incompleteness of the sample, these detection rates may represent the lower limits. The selection of more extended sources and dilution by HI emission at lower redshifts may contribute to the lower detection rate of HI absorption lines. These detected absorbers present relatively narrow line widths and comparable column densities consistent with previous observations. One absorber has a symmetric profile with a large velocity offset, while the other two show asymmetric profiles that can be decomposed into multiple components, suggesting various possibilities of gas origins and kinematics. These HI absorbers may have connections with rotating disks, gas outflows, galactic gas clouds, gas fueling of the AGN, and jet-ISM interactions, which will be further investigated with the upcoming systematic survey and spatially resolved observations.

The Population of the Galactic Center Filaments: Position Angle Distribution Reveal a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane

Authors: F. Yusef-Zadeh, R. G. Arendt, M. Wardle, I. Heywood
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01071
Pdf link: https://arxiv.org/pdf/2306.01071
Abstract
We have examined the distribution of the position angle (PA) of the Galactic center filaments with lengths $L > 66''$ and $ < 66''$ as well as their length distribution as a function of PA. We find bimodal PA distributions of the filaments, long and short populations of radio filaments. Our PA study shows the evidence for a distinct population of short filaments with PA close to the Galactic plane. Mainly thermal short radio filaments ($<66''$) have PAs concentrated close to the Galactic plane within $60^\circ < \rm PA <120^\circ$. Remarkably, the short filament PAs are radial with respect to the Galactic center at $l <0^\circ$, and extend in the direction toward Sgr A*. On a smaller scale, the prominent Sgr E HII complex G358.7-0.0 provides a vivid example of the nearly radial distribution of short filaments. The bimodal PA distribution suggests different origin for two distinct filament populations. We argue that alignment of the short filament population results from the ram pressure of a degree-scale outflow from Sgr A* that exceeds the internal filament pressure, and aligns them along the Galactic plane. The ram pressure is estimated to be 2$\times10^6,$ cm$^{-3},$ K at a distance of 300pc, requiring biconical mass outflow rate $10^{-4}$ \msol, yr$^{-1}$ with an opening angle of $\sim40^\circ$. This outflow aligns not only the magnetized filaments along the Galactic plane but also accelerates thermal material associated with embedded or partially embedded clouds. This places an estimate of $\sim$6 Myr as the age of the outflow.

Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph -- III. Dust Grains in Young L Dwarf Atmospheres Are Heavier

Authors: Genaro Suárez (1,2), Stanimir Metchev (2) ((1) American Museum of Natural History, (2) The University of Western Ontario)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.01119
Pdf link: https://arxiv.org/pdf/2306.01119
Abstract
Analysis of all archival 5--14 micron spectra of field ultracool dwarfs from the Infrared Spectrograph on the Spitzer Space Telescope has shown that absorption by silicates in the 8--11 micron region is seen in most L-type (1300 K to 2200 K) dwarfs. The absorption is caused by silicate-rich clouds in the atmospheres of L dwarfs and is strongest at L4--L6 spectral types. Herein we compare averages of the mid-infrared silicate absorption signatures of L3--L7 dwarfs that have low ($\lesssim$10$^{4.5}$ cm s$^{-2}$) vs.\ high ($\gtrsim$10$^5$ cm s$^{-2}$) surface gravity. We find that the silicate absorption feature is sensitive to surface gravity and indicates a difference in grain size and composition between dust condensates in young and old mid-L dwarfs. The mean silicate absorption profile of low-gravity mid-L dwarfs matches expectations for $\sim$1 micron-sized amorphous iron- and magnesium-bearing pyroxene (Mg$x$Fe${1-x}$SiO$_3$) grains. High-gravity mid-L dwarfs have silicate absorption better represented by smaller ($\lesssim$0.1 $\mu$m) and more volatile amorphous enstatite (MgSiO$_3$) or SiO grains. This is the first direct spectroscopic evidence for gravity-dependent sedimentation of dust condensates in ultracool atmospheres. It confirms theoretical expectations for lower sedimentation efficiencies in low-gravity atmospheres and independently confirms their increased dustiness.

Rapid Variability of the accretion disk wind in the narrow line Seyfert 1, PG 1448+273

Authors: James Reeves, Valentina Braito, Delphine Porquet, Marco Laurenti, Andrew Lobban, Gabriele Matzeu
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01151
Pdf link: https://arxiv.org/pdf/2306.01151
Abstract
PG 1448+273 is a luminous, nearby ($z=0.0645$), narrow line Seyfert 1 galaxy, which likely accretes close to the Eddington limit. XMM-Newton observations of PG 1448+273 in 2017 revealed the presence of an ultra fast outflow, as seen through its blueshifted iron K absorption profile, with an outflow velocity of about $0.1c$. Here, the first NuSTAR observation of PG 1448+273, performed in 2022 and coordinated with XMM-Newton is presented, which shows remarkable variability of its ultra fast outflow. The average count rate is a factor of 2 lower during the last 60 ks of the NuSTAR observation, where a much faster component of the ultra fast outflow was detected with a terminal velocity of $0.26\pm0.04c$. This is significantly faster than the outflow component which was initially detected in 2017, when overall PG 1448+273 was observed at a lower X-ray flux and which implies an order of magnitude increase in the wind kinetic power between the 2017 and 2022 epochs. Furthermore, the rapid variability of the ultra fast outflow in 2022, on timescales down to 10 ks, suggests we are viewing through a highly inhomogeneous disk wind in PG 1448+273, where the passage of a denser wind clump could account for the increase in obscuration in the last 60 ks of the NuSTAR observation.

Distance of PSR B0458+46 indicated by FAST HI absorption observations

Authors: W. C. Jing, J. L. Han, Tao Hong, Chen Wang, X. Y. Gao, L. G. Hou, D. J. Zhou, J. Xu, Z. L. Yang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.01246
Pdf link: https://arxiv.org/pdf/2306.01246
Abstract
The pulsar B0458+46 was previously believed to have a distance of about 1.3$$kpc and to be associated with a nearby supernova remnant, SNR HB9 (G160.9+2.6). We observe the neutral hydrogen (HI) absorption spectrum of PSR B0458+46 by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), and detect two absorption lines at radial velocities of $V_{\rm LSR} = {-7.7}{\rm km~~s}^{-1}$ and $-28.1~~{\rm km~s^{-1}}$. Based on the Galactic rotation curve with a modification factor correcting for the systematic stream in the anticenter region, we derive the kinematic distance of the farther absorption clouds, which are found to be located $2.7^{+0.9}{-0.8}$ kpc away, just beyond the Perseus Arm. We also obtain a direct distance estimation of the absorption clouds, being $2.3{-0.7}^{+1.1}$ kpc, based on a comparison of their velocity with the HI emission in the Perseus and Outer Arms that was well-defined by recently measured parallax tracers. As a result, we conclude that PSR B0458+46 should be located beyond the Perseus Arm, with a lower limit distance of 2.7 kpc, and therefore not associated with SNR HB9. The doubled distance indicates a deficiency of thermal electrons in the immediate outer Galaxy, with much less density than current models predict. Additionally, we detect a new high-velocity HI cloud in the direction of this pulsar.

Inaccuracies and biases of the Gaussian size deconvolution for extracted sources and filaments

Authors: Alexander Men'shchikov
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01563
Pdf link: https://arxiv.org/pdf/2306.01563
Abstract
A simple Gaussian size deconvolution method is routinely used to remove the blur of observed images caused by insufficient angular resolutions of existing telescopes, thereby to estimate the physical sizes of extracted sources and filaments. The size deconvolution method is expected to work when the structures, as well as the telescope beams, have Gaussian shapes. This study employs model images of the spherical and cylindrical objects with Gaussian and power-law shapes, representing the dense cores and filaments. The images are convolved to a wide range of angular resolutions to probe various degrees of resolvedness of the models. Simplified flat, convex, and concave backgrounds are added to the images, then planar backgrounds across the footprints of the structures are subtracted and sizes are measured and deconvolved. When background subtraction is inaccurate, the structures acquire profoundly non-Gaussian profiles. The deconvolved half maximum sizes can be strongly under- or overestimated, by factors of up to ~20 when the structures are unresolved or partially resolved. For resolved structures, the errors are within a factor of ~2, although for some power-law models show the factors of up to ~6. The size deconvolution method cannot be applied to unresolved structures, it can be used only for the Gaussian-like structures, including the critical Bonnor-Ebert spheres, when they are at least partially resolved. The method must be considered inapplicable for the power-law structures with shallow profiles. This work also reveals subtle properties of convolution for different geometries. When convolved with different kernels, spherical objects and cylindrical filaments with identical profiles obtain different widths and shapes. A filament, imaged by the telescope with a non-Gaussian PSF, could appear substantially shallower than the structure is in reality, even when it is resolved.

HYPERION. Merger and outflow in the most luminous $z>6$ quasar

Authors: R. Tripodi, J. Scholtz, R. Maiolino, S. Fujimoto, S. Carniani, J. D. Silverman, C. Feruglio, M. Ginolfi, L. Zappacosta, T. Costa, G. C. Jones, E. Piconcelli, M. Bischetti, F. Fiore
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01644
Pdf link: https://arxiv.org/pdf/2306.01644
Abstract
We present ALMA deep observations of the [CII] 158 $\mu$m emission line and the continuum at 253 GHz and 99 GHz towards SDSS J0100+2802 at $z\simeq 6.3$, the most luminous QSO at z$>$6. It belongs to the HYPERION sample of luminous QSOs at $z\sim 6-7.5$. The observations (at 2.2$''$ resolution in band 3 and 0.9$''$ resolution in band 6) are optimized to detect extended emission around the QSO. We detect a merging, tidally disrupted companion both in [CII] and in continuum, stretching on scales up to 20 kpc from the quasar, with a knotty morphology. For the newly-detected companion we estimate a dust mass of $M_{\rm dust}=(0.6-4.3)\times 10^7\ \rm M_\odot$, an SFR in the range $[43-402]\ \rm M_\odot$, that is remarkably similar to the SFR of the QSO, and a neutral gas mass of $M_{\rm HI}=3.3\times 10^9\ \rm M_{\odot}$, suggesting that both the QSO and its companion are gas rich and that the major merging may be at the origin of the boosted star formation. This close merging companion is undetected by deep JWST imaging observations, supporting the effectiveness of ALMA in detecting dust obscured sources especially in the vicinity of optically bright quasars. We also detect a broad blueshifted component in the [CII] spectrum aligned with the radio jet of the QSO, suggesting that this may be the first detection of a radio jet - driven outflow at such high redshift. We estimate a mass outflow rate in the range $\dot{M}{\rm out}=(115-269)\ \rm M\odot\ yr^{-1}$. The outflow energetics is similar to that of ionized outflows found in other QSOs host at lower redshift, and the low momentum loading factor suggests that this outflow would not be very effective in removing the gas from the entire galaxy. These results highlight the importance of deep medium-resolution ALMA observations for the study of QSOs and their environment at the Epoch of Reionization.

In-situ enrichment in heavy elements of hot Jupiters

Authors: A. Morbidelli, K. Batygin, E. Lega
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.01653
Pdf link: https://arxiv.org/pdf/2306.01653
Abstract
Context: Radius and mass measurements of short-period giant planets reveal that many of these planets contain a large amount of heavy elements, in sharp contrast with the expectations of the conventional core-accretion model for the origin of giant planets. Aims: The proposed explanations for the heavy-element enrichment of giant planets fall short of explaining the most enriched planets. We look for additional processes that can explain the full envelope of inferred enrichments. Methods: We revisit the dynamics of pebbles and dust in the vicinity of giant planets using analytic estimates. Although our results are derived in the framework of a viscous alpha-disk we also discuss the case of disks driven by angular momentum removal in magnetized winds. Results: When giant planets are far from the star, dust and pebbles are confined in a pressure bump at the outer edge of the planet-induced gap. Instead, when the planets reach the inner part of the disk (r << 2 au), dust penetrates the gap together with the gas. The dust/gas ratio can be enhanced by more than an order of magnitude if radial drift of dust is not impeded farther out by other barriers. Thus, hot planets undergoing runaway gas accretion can swallow a large amount of dust. Conclusions: Whereas the gas accreted by giant planets in the outer disk is very dust-poor, that accreted by hot planets can be extremely dust-rich. Thus, provided that a large fraction of the atmosphere of hot-Jupiters is accreted in situ, a large amount of dust can be accreted as well. We draw a distinction between this process and pebble accretion, which is ineffective at small stellocentric radii, even for super-Earths. Giant planets farther out in the disk are extremely effective barriers against the flow of pebbles and dust across their gap.

SOFIA/HAWC+ far-infrared polarimetric large area CMZ exploration (fireplace) survey I: General results from the pilot program

Authors: Natalie O. Butterfield, David T. Chuss, Jordan A. Guerra, Mark R. Morris, Dylan Pare, Edward J. Wollack, C. Darren Dowell, Matthew J. Hankins, Javad Siah, Johannes Staguhn, Ellen Zweibel
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.01681
Pdf link: https://arxiv.org/pdf/2306.01681
Abstract
We present the first data release (DR1) of the Far-Infrared Polarimetric Large Area CMZ Exploration (FIREPLACE) survey. The survey was taken using the 214-micron band of the HAWC+ instrument with the SOFIA telescope (19.6" resolution; 0.7 pc). In this first data release we present dust polarization observations covering a ~0.5degree region of the Galactic Center's Central Molecular Zone (CMZ), centered on the Sgr B2 complex. We detect ~25,000 Nyquist-sampled polarization pseudovectors, after applying the standard SOFIA cuts for minimum signal-to-noise in fractional polarization and total intensity of 3 and 200, respectively. Analysis of the magnetic field orientation suggests a bimodal distribution in the field direction. This bimodal distribution shows enhancements in the distribution of field directions for orientations parallel and perpendicular to the Galactic plane, which is suggestive of a CMZ magnetic field configuration with polodial and torodial components. Furthermore, a detailed analysis of individual clouds included in our survey (i.e., Sgr B2, Sgr B2-NW, Sgr B2-Halo, Sgr B1, and Clouds-E/F) shows these clouds have fractional polarization values of 1-10% at 214-micron, with most of the emission having values <5%. A few of these clouds (i.e., Sgr B2, Clouds-E/F) show relatively low fractional polarization values toward the cores of the cloud, with higher fractional polarization values toward the less dense periphery. We also observe higher fractional polarization towards compact HII regions which could indicate an enhancement in the grain alignment in the dust surrounding these sources.

by olozhika (Xing Yuchen).

2023-06-05

New submissions for Mon, 8 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-08

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 12papers

Site-testing at the Muztagh-ata Site.V. Nighttime Cloud Amount during the Last Five Years

Authors: Jing Xu, Guo-jie Feng, Guang-xin Pu, Le-tian Wang, Zi-Huang Cao, Li-Qing Ren, Xuan Zhang, Shu-guo Ma, Chun-hai Bai, Ali Esamdin, Jian Li, Yuan Tian, Zheng Wang, Yong-heng Zhao, Jian-rong Shi
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.03067
Pdf link: https://arxiv.org/pdf/2305.03067
Abstract
The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns. Cloud coverage is directly related to the amount of time available for scientific observations at observatories. In this article, we report on the results of detailed night-time cloud statistics and continuous observing me derived from ground-based all-sky cameras at the Muztagh-ata site from 2017 to 2021. Results obtained from acquisition data show that the proportion of the annual observing me at the Muztagh-ata site is 65%, and the best period with the least cloud coverage and longer continuous observing time is from September to February. We made a comparison of the monthly mean observing nights obtained from our all-sky cameras and CLARA dataset, results show that the discrepancy between them may depend on the cloud top heights. On average, this site can provide 175 clear nights and 169 nights with at least 4 hours of continuous observing time per year.

A giant thin stellar stream in the Coma Galaxy Cluster

Authors: Javier Román, R. Michael Rich, Niusha Ahvazi, Laura Sales, Chester Li, Giulia Golini, Ignacio Trujillo, Johan H. Knapen, Reynier F. Peletier, Pablo M. Sánchez-Alarcón
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.03073
Pdf link: https://arxiv.org/pdf/2305.03073
Abstract
The study of dynamically cold stellar streams reveals information about the gravitational potential where they reside and provides important constraints on dark matter properties. However, their intrinsic faintness makes detection beyond Local environments highly challenging. Here we report the detection of an extremely faint stellar stream (mu_g,max = 29.5 mag arcsec-2) with an extraordinarily coherent and thin morphology in the Coma Galaxy Cluster. This Giant Coma Stream spans 510 kpc in length and appears as a free-floating structure located at a projected distance of 0.8 Mpc from the center of Coma. We do not identify any potential galaxy remnant or core, and the stream structure appears featureless in our data. We interpret the Giant Coma Stream as being a recently accreted, tidally disrupting dwarf of M* ~ 10^8 Msun, and report a case with similar characteristics within the Illustris-TNG50 simulation. Our work shows the presence of free-floating, extremely faint and thin stellar streams in galaxy clusters, widening the environmental context for their promising future applications in the study of dark matter properties.

The isotropic center of NGC 5419 -- A core in formation?

Authors: Bianca Neureiter, Jens Thomas, Antti Rantala, Thorsten Naab, Kianusch Mehrgan, Roberto Saglia, Stefano de Nicola, Ralf Bender
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.03078
Pdf link: https://arxiv.org/pdf/2305.03078
Abstract
With its cored surface brightness profile, the elliptical galaxy NGC 5419 appears as a typical high-mass early-type galaxy (ETG). However, the galaxy hosts two distinct nuclei in its center. We use high-signal MUSE (Multi-Unit Spectroscopic Explorer) spectral observations and novel triaxial dynamical orbit models to reveal a surprisingly isotropic central orbit distribution in NGC 5419. Recent collisionless simulations of merging massive ETGs suggest a two-phase core formation model, in which the low-density stellar core forms rapidly by supermassive black holes (SMBHs) sinking into the center due to dynamical friction. Only afterwards the SMBHs form a hard binary and the black hole scouring process slowly changes the central orbit distribution from isotropic to tangential. The observed cored density profile, the double nucleus and the isotropic center of NGC 5419 together thus point to an intermediate evolutionary state where the first phase of the core formation has taken place, yet the scouring process is only beginning. This implies that the double nucleus is a SMBH binary. Our triaxial dynamical models indicate a total mass of the two SMBHs in the center of NGC 5419 of MBH = (1.0 +/- 0.08) 10^10 Msol. Moreover, we find that NGC 5419's complex kinematically distinct core (KDC) can be explained by a coherent flip of the orbital rotation direction of stars on tube orbits at ~3kpc distance from the galaxy center together with projection effects. This is also in agreement with merger simulations hosting SMBHs in the same mass regime.

CHEX-MATE: Constraining the origin of the scatter in galaxy cluster radial X-ray surface brightness profiles

Authors: I. Bartalucci, S. Molendi, E. Rasia, G.W. Pratt, M. Arnaud, M. Rossetti, F. Gastaldello, D. Eckert, M. Balboni, S. Borgani, H. Bourdin, M.G. Campitiello, S. De Grandi, M. De Petris, R.T. Duffy, S. Ettori, A. Ferragamo, M. Gaspari, R. Gavazzi, S. Ghizzardi, A. Iqbal, S.T. Kay, L. Lovisari, P. Mazzotta, B.J. Maughan, E. Pointecouteau, G. Riva, M. Sereno
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.03082
Pdf link: https://arxiv.org/pdf/2305.03082
Abstract
We investigate the statistical properties and the origin of the scatter within the spatially resolved surface brightness profiles of the CHEX-MATE sample, formed by 118 galaxy clusters selected via the SZ effect. These objects have been drawn from the Planck SZ catalogue and cover a wide range of masses, M${500}=[2-15] \times 10^{14} $M${\odot}$, and redshift, z=[0.05,0.6]. We derived the surface brightness and emission measure profiles and determined the statistical properties of the full sample. We found that there is a critical scale, R$\sim 0.4 R_{500}$, within which morphologically relaxed and disturbed object profiles diverge. The median of each sub-sample differs by a factor of $\sim 10$ at $0.05,R_{500}$. There are no significant differences between mass- and redshift-selected sub-samples once proper scaling is applied. We compare CHEX-MATE with a sample of 115 clusters drawn from the The Three Hundred suite of cosmological simulations. We found that simulated emission measure profiles are systematically steeper than those of observations. For the first time, the simulations were used to break down the components causing the scatter between the profiles. We investigated the behaviour of the scatter due to object-by-object variation. We found that the high scatter, approximately 110%, at $R<0.4R_{500}$ is due to a genuine difference between the distribution of the gas in the core. The intermediate scale, $R_{500} =[0.4-0.8]$, is characterised by the minimum value of the scatter on the order of 0.56, indicating a region where cluster profiles are the closest to the self-similar regime. Larger scales are characterised by increasing scatter due to the complex spatial distribution of the gas. Also for the first time, we verify that the scatter due to projection effects is smaller than the scatter due to genuine object-by-object variation in all the considered scales. [abridged]

A Chandra X-ray Study of Supernova Remnant N63A in the Large Magellanic Cloud

Authors: E. Karagoz, N. Alan, S. Bilir, S. Ak
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.03084
Pdf link: https://arxiv.org/pdf/2305.03084
Abstract
We perform extensive spectroscopy of the supernova remnant N63A in the Large Magellanic Cloud, using $\sim 43$ ks {\it Chandra} archival data. By analysing the spectra of the entire remnant, we determine the abundance distributions for O, Ne, Mg, Si, and Fe. We detect evidence of enhanced O and possibly Ne and Mg in some of the central regions which might indicate an asymmetric distribution of the ejecta. The average O/Ne, O/Mg, and Ne/Mg abundance ratios of the ejecta are in plausible agreement with the nucleosynthesis products from the explosion of a $\sim40$ $M_{\odot}$ progenitor. We estimate an upper limit on the Sedov age of $\sim 5,400\pm200$ yr and explosion energy of $\sim 8.9\pm 1.6\times 10^{51}$ erg for N63A. We discuss the implications of our results for the morphological structure of the remnant, its circumstellar medium and the nature of the progenitor star.

Complete replacement of magnetic flux in a flux rope during a coronal mass ejection

Authors: Tingyu Gou, Rui Liu, Astrid M. Veronig, Bin Zhuang, Ting Li, Wensi Wang, Mengjiao Xu, Yuming Wang
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.03217
Pdf link: https://arxiv.org/pdf/2305.03217
Abstract
Solar coronal mass ejections are the most energetic events in the Solar System. In their standard formation model, a magnetic flux rope builds up into a coronal mass ejection through magnetic reconnection that continually converts overlying, untwisted magnetic flux into twisted flux enveloping the pre-existing rope. However, only a minority of coronal mass ejections carry a coherent magnetic flux rope as their core structure, which casts doubt on the universality of this orderly wrapping process. Here we provide observational evidence of a different formation and eruption mechanism of a magnetic flux rope from an S-shaped thread, where its magnetic flux is fully replaced via flare reconnections. One of the footpoints of the sigmoidal feature slipped and expanded during the formation, and then moved to a completely new place, associated with the highly dynamical evolution of flare ribbons and a twofold increase in magnetic flux through the footpoint, during the eruption. Such a configuration is not predicted by standard formation models or numerical simulations and highlights the three-dimensional nature of magnetic reconnections between the flux rope and the surrounding magnetic field.

A Catalog of Distance Determinations for the LAMOST DR8 K Giants in the Galactic Halo

Authors: Lan Zhang, Xiang-Xiang Xue, Chengqun Yang, Feilu Wang, Hans-Walter Rix, Gang Zhao, Chao Liu
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.03311
Pdf link: https://arxiv.org/pdf/2305.03311
Abstract
We present a catalog of distances for 19544 K giants drawn from LAMOST DR8. Most of them are located in the halo of the Milky Way up to ~~120~~kpc. There are 15% K giants without SDSS photometry, for which we supplements with Pan-STARRS1 (PS1) photometry calibrated to SDSS photometric system. The possible contamination of the red clumps/horizontal branch are removed according to metallicities and colors before the distance determination. Combining the LAMOST spectroscopic metallicities with the SDSS/PS1 photometry, we estimate the absolute magnitudes in SDSS $r-$band, the distance moduli, and the corresponding uncertainties through an Bayesian approach devised by Xue et al. (2014) for the SEGUE halo K-giants. The typical distance precision is about 11%. The stars in the catalog lie in a region of 4-126 kpc from the Galactic center, of which with 6, 320 stars beyond 20 kpc and 273 stars beyond 50 kpc, forming the largest spectroscopic sample of distant tracers in the Milky Way halo so far.

Chemical and physical properties of cometary dust

Authors: Cecile Engrand, Jérémie Lasue, Diane H. Wooden, Mike E. Zolensky
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.03417
Pdf link: https://arxiv.org/pdf/2305.03417
Abstract
Cometary dust particles are best preserved remnants of the matter present at the onset of the formation of the Solar System. Space missions, telescopic observations and laboratory analyses advanced the knowledge on the properties of cometary dust. Cometary samples were returned from comet 81P/Wild2 by the Stardust mission. The chondritic (porous) anhydrous interplanetary dust particles and chondritic porous micrometeorites, and the ultracarbonaceous Antarctic micrometeorites (UCAMMs) also show strong evidence for a cometary origin. The composition of cometary dust is generally chondritic, but with high C and N compared with CI. The cometary organic matter is mixed with minor amounts of crystalline and amorphous minerals. The most abundant crystalline minerals are ferromagnesian silicates, refractory minerals and low Ni Fe sulfides are also present. The presence of carbonates in cometary dust is still debated, but a phyllosilicate-like phase was observed in a UCAMM. GEMS phases are usually abundant. Some of the organic matter present in cometary dust particle resembles the insoluble organic matter present in primitive meteorites, but amorphous carbon and exotic (e.g. N-rich) organic phases are also present. The H isotopic composition of the organic matter traces a formation at very low temperatures, in the protosolar cloud or in the outer regions of the protoplanetary disk. The presolar dust concentration in cometary dust can reach about 1%, which is the most elevated value observed in extraterrestrial samples. The differential size distribution of cometary dust in comet trails is well represented by a power-law distribution with a mean power index N typically ranging from -3 to -4. Polarimetric and light scattering studies suggest mixtures of porous agglomerates of sub-micrometer minerals with organic matter. Cometary dust particles have low tensile strength, and low density.

Mildly Relativistic Motion in the Radio Quiet Quasar PG 1351+640

Authors: Ailing Wang, Tao An, Shaoguang Guo, Luis C. Ho, Willem A. Baan, Robert Braun, Sina Chen, Xiaopeng Cheng, Philippa Hartley, Jun Yang, Yingkang Zhang
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.03470
Pdf link: https://arxiv.org/pdf/2305.03470
Abstract
Measuring the proper motion of the emission component in radio-quiet quasars (RQQs) could help to distinguish between the origins of the radio emission and to understand whether the jet production mechanism is the same in radio-loud quasars (RLQs) and RQQs. PG 1351+640 is one of the few RQQs suitable for proper motion studies: it has two compact components on milli-arcsecond scales, a flat-spectrum core and a steep-spectrum jet; both components are >2 mJy at 5 GHz and are well suited for Very Long Baseline Array (VLBA) observations. We compare recent VLBA observations with that made seventeen years ago and find no significant change in the core-jet separation between 2005 and 2015 (a proper motion of 0.003 mas yr-1). However, the core-jet separation increased significantly between 2015 and 2022, inferring a jet proper motion velocity of 0.063 mas yr-1, which corresponds to an apparent transverse velocity of 0.37c. The result suggests that the jet of the RQQ PG 1351+640 is mildly relativistic and oriented at a relatively small viewing angle.

The first massive compact companion in a wide orbit around a hot subdwarf star

Authors: S. Geier, M. Dorsch, H. Dawson, I. Pelisoli, J. Munday, T. R. Marsh, V. Schaffenroth, U. Heber
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.03475
Pdf link: https://arxiv.org/pdf/2305.03475
Abstract
We report the discovery of the first hot subdwarf B (sdB) star with a massive compact companion in a wide ($P=892.5\pm60.2,{\rm d}$) binary system. It was discovered based on an astrometric binary solution provided by the Gaia mission Data Release 3. We performed detailed analyses of the spectral energy distribution (SED) as well as spectroscopic follow-up observations and confirm the nature of the visible component as a sdB star. The companion is invisible despite of its high mass of $M_{\rm comp}=1.50_{-0.45}^{+0.37},M_{\rm \odot}$. A main sequence star of this mass would significantly contribute to the SED and can be excluded. The companion must be a compact object, either a massive white dwarf or a neutron star. Stable Roche lobe overflow to the companion likely led to the stripping of a red giant and the formation of the sdB, the hot and exposed helium core of the giant. Based on very preliminary data, we estimate that $\sim9%$ of the sdBs might be formed through this new channel. This binary might also be the prototype for a new progenitor class of supernovae type Ia, which has been predicted by theory.

Elasticity of neutron star mantle: improved compressible liquid drop model for cylindrical phases

Authors: Nikita A. Zemlyakov, Andrey I. Chugunov (Ioffe Institute)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2305.03603
Pdf link: https://arxiv.org/pdf/2305.03603
Abstract
Neutron stars are the densest objects in the Universe. They have microscopically homogeneous core and heterogeneous crust. In particular, there may be a specific layer inside neutron stars, the mantle, which consists of substantially non-spherical nuclei immersed in a background of relativistic degenerate electrons and quasi-free neutrons. In this paper we reconsider transverse shear modulus for cylindrical phases of the mantle within the framework of compressible liquid drop model. We demonstrate that transverse shear affects the shape of nuclear clusters: their cross-section becomes elliptical. This effect reduces respective elastic constant. Using a simple model we perform all derivations analytically and obtain the expression for the transverse shear modulus, which can be useful for astrophysical applications.

The role of the drag force in the gravitational stability of dusty planet-forming disc -- II. Numerical simulations

Authors: Cristiano Longarini, Philip J. Armitage, Giuseppe Lodato, Daniel J. Price, Simone Ceppi
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.03659
Pdf link: https://arxiv.org/pdf/2305.03659
Abstract
Young protostellar discs are likely to be both self-gravitating, and to support grain growth to sizes where the particles decoupled from the gas. This combination could lead to short-wavelength fragmentation of the solid component in otherwise non-fragmenting gas discs, forming Earth-mass solid cores during the Class 0/I stages of Young Stellar Object evolution. We use three-dimensional smoothed particle hydrodynamics simulations of two-fluid discs, in the regime where the Stokes number of the particles St>1, to study how the formation of solid clumps depends on the disc-to-star mass ratio, the strength of gravitational instability, and the Stokes number. Gravitational instability of the simulated discs is sustained by local cooling. We find that the ability of the spiral structures to concentrate solids increases with the cooling time, and decreases with the Stokes number, while the relative dynamical temperature between gas and dust of the particles decreases with the cooling time and the disc-to-star mass ratio, and increases with the Stokes number. Dust collapse occurs in a subset of high disc mass simulations, yielding clumps whose mass is close to linear theory estimates, namely 1-10 Earth masses. Our results suggest that if planet formation occurs via this mechanism, the best conditions correspond to near the end of the self-gravitating phase, when the cooling time is long and the Stokes number close to unity.

New submissions for Tue, 2 May 23

Keyword: star formation

Molecular gas content and high excitation of a massive main-sequence galaxy at z = 3

Authors: Han Lei, Francesco Valentino, Georgios E. Magdis, Vasily Kokorev, Daizhong Liu, Dimitra Rigopoulou, Shuowen Jin, Emanuele Daddi
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00024
Pdf link: https://arxiv.org/pdf/2305.00024
Abstract
We present new CO ($J=5-4$ and $7-6$) and [CI] ($^3P_2,-, ^3P_1$ and $^3P_1,-, ^3P_0$) emission line observations of the star-forming galaxy D49 at the massive end of the Main Sequence at $z=3$. We incorporate previous CO ($J=3-2$) and optical-to-millimetre continuum observations to fit its spectral energy distribution (SED). Our results hint at high-$J$ CO luminosities exceeding the expected location on the empirical correlations with the infrared luminosity. [CI] emission fully consistent with the literature trends is found. We do not retrieve any signatures of a bright active galactic nucleus that could boost the $J=5-4,,7-6$ lines in either the infrared or X-ray bands, but warm photon-dominated regions, shocks or turbulence could in principle do so. We suggest that mechanical heating could be a favourable mechanism able to enhance the gas emission at fixed infrared luminosity in D49 and other main-sequence star-forming galaxies at high redshift, but further investigation is necessary to confirm this explanation. We derive molecular gas masses from dust, CO, and [CI] that all agree within the uncertainties. Given its large star formation rate (SFR) $\sim 500~~M_\odot~~{\rm yr}^{-1}$ and stellar mass $>10^{11.5}~M_\odot$, the short depletion time scale of $<0.3$ Gyr might indicate that D49 is experiencing its last growth spurt and will soon transit to quiescence.

Feedback-driven anisotropy in the circumgalactic medium for quenching galaxies in the SIMBA simulations

Authors: Tianyi Yang, Romeel Davé, Weiguang Cui, Yan-Chuan Cai, John A. Peacock, Daniele Sorini
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.00602
Pdf link: https://arxiv.org/pdf/2305.00602
Abstract
We use the SIMBA galaxy formation simulation suite to explore anisotropies in the properties of circumgalactic gas that result from accretion and feedback processes. We particularly focus on the impact of bipolar active galactic nuclei (AGN) jet feedback as implemented in SIMBA, which quenches galaxies and has a dramatic effect on large-scale gas properties. We show that jet feedback at low redshifts is most common in the stellar mass range $(1-5)\times 10^{10}M_\odot$, so we focus on galaxies with active jets in this mass range. In comparison to runs without jet feedback, jets cause lower densities and higher temperatures along the galaxy minor axis (SIMBA jet direction) at radii >=$0.5r_{200c}-4r_{200c}$ and beyond. This effect is less apparent at higher or lower stellar masses, and is strongest within green valley galaxies. The metallicity also shows strong anisotropy out to large scales, driven by star formation feedback. We find substantially stronger anisotropy at <=$0.5r_{200c}$, but this also exists in runs with no explicit feedback, suggesting that it is due to anisotropic accretion. Finally, we explore anisotropy in the bulk radial motion of the gas, finding that both star formation and AGN wind feedback contribute to pushing the gas outwards along the minor axis at <=1 Mpc, but AGN jet feedback further causes bulk outflow along the minor axis out to several Mpc, which drives quenching via gas starvation. These results provide observational signatures for the operation of AGN feedback in galaxy quenching.

Keyword: molecular cloud

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Keyword: N-PDF

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New submissions for Wed, 14 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 3papers

Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life

Authors: William Bains, Janusz J. Petkowski, Sara Seager
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.07358
Pdf link: https://arxiv.org/pdf/2306.07358
Abstract
Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50-100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as "uninhabitable", and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there.

Excited Hydroxyl Outflow in the High-Mass Star-Forming Region G34.26+0.15

Authors: W. S. Tan, (1,2), E. D. Araya (1,3), C. Rigg (4), P. Hofner (3,5), S. Kurtz (6), H. Linz (7), V. Rosero (5) ((1) Physics Department, Western Illinois University, Macomb, IL, USA, (2) National University of Singapore, 21 Lower Kent Ridge Rd, Singapore 119077, (3) New Mexico Institute of Mining and Technology, Physics Department, Socorro, NM, USA, (4) Southeastern High School, 90 W Green St, Augusta, IL, USA, (5) National Radio Astronomy Observatory, Socorro, NM, USA, (6) Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antig. Carr. a Pátzcuaro 8701, 58089, Morelia, Michoacán, México, (7) Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany.)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.07394
Pdf link: https://arxiv.org/pdf/2306.07394
Abstract
G34.26+0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hyper-compact HII regions and a prototypical cometary ultra-compact HII region. Previous high-sensitivity single dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blue-shifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at $\sim 2$" scales, and it is coincident with one of the bright ionized cores of the cometary HII region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultra-compact HII region.

Detecting Fast Radio Bursts with Spectral Structure using the Continuous Forward Algorithm

Authors: Pravir Kumar, Barak Zackay, Casey J. Law
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.07914
Pdf link: https://arxiv.org/pdf/2306.07914
Abstract
Detecting Fast Radio Bursts (FRBs) with frequency-dependent intensity remains a challenge, as existing search algorithms do not account for the spectral shape and might have resulted in non-detections. We propose a novel detection statistic, which we call the Kalman detector, that improves the sensitivity of FRB signal detection by incorporating spectral shape information. The detection statistic is based on an optimal matched filter, marginalizing over all possible intensity functions, weighted by a random walk probability distribution, considering some decorrelation bandwidth. Our analysis of previously detected FRBs demonstrates that the Kalman score provides a comparable yet independent source of information for bursts with significant spectral structure and the sensitivity improvement is of the order of 0-200%, with a median improvement of 20%. We also apply the Kalman detector to existing data from FRB 20201124A and detect two new repeat bursts which were previously missed. Furthermore, we suggest a practical implementation for real-time surveys by employing a low significance soft-trigger from initial integration-based detection algorithms. The Kalman detector has the potential to significantly enhance FRB detection capabilities and enable new insights into the spectral properties of these enigmatic astrophysical phenomena.

by olozhika (Xing Yuchen).

2023-06-14

New submissions for Tue, 2 May 23

Keyword: star formation

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Keyword: molecular cloud

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Keyword: N-PDF

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Keyword: cloud

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Keyword: interstellar medium

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Keyword: core

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Keyword: filament

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Keyword: atomic gas

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New submissions for Fri, 9 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 9papers

A Tight Correlation Between Millimeter and X-ray Emission in Accreting Massive Black Holes from <100 Milliarcsecond-resolution ALMA Observations

Authors: Claudio Ricci, Chin-Shin Chang, Taiki Kawamuro, George Privon, Richard Mushotzky, Benny Trakhtenbrot, Ari Laor, Michael J. Koss, Krista L. Smith, Kriti K. Gupta, Georgios Dimopoulos, Susanne Aalto, Eduardo Ros
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.04679
Pdf link: https://arxiv.org/pdf/2306.04679
Abstract
Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGN) could be created by the same population of electrons that gives rise to the X-ray emission that is ubiquitously observed in accreting black holes. We present the results of a dedicated high spatial resolution ($\sim$60-100 milliarcsecond) ALMA campaign on a volume-limited ($<50$ Mpc) sample of 26 hard X-ray ($>10$ keV) selected radio-quiet AGN. We find an extremely high detection rate (25/26 or $94^{+3}{-6}%$), which shows that nuclear emission at mm-wavelenghts is nearly ubiquitous in accreting SMBHs. Our high-resolution observations show a tight correlation between the nuclear (1-23 pc) 100GHz and the intrinsic X-ray emission (1$\sigma$ scatter of $0.22$ dex). The ratio between the 100GHz continuum and the X-ray emission does not show any correlation with column density, black hole mass, Eddington ratio or star formation rate, which suggests that the 100GHz emission can be used as a proxy of SMBH accretion over a very broad range of these parameters. The strong correlation between 100GHz and X-ray emission in radio-quiet AGN could be used to estimate the column density based on the ratio between the observed 2-10keV ($F^{\rm obs}{2-10\rm,keV}$) and 100GHz ($F_{100\rm,GHz}$) fluxes. Specifically, a ratio $\log (F^{\rm obs}{2-10\rm,keV}/F{100\rm,GHz})\leq 3.5$ strongly suggests that a source is heavily obscured [$\log (N_{\rm H}/\rm cm^{-2})\gtrsim 23.8$]. Our work shows the potential of ALMA continuum observations to detect heavily obscured AGN (up to an optical depth of one at 100GHz, i.e. $N_{\rm H}\simeq 10^{27}\rm,cm^{-2}$), and to identify binary SMBHs with separations $<100$ pc, which cannot be probed by current X-ray facilities.

The Prevalence of the $α$-bimodality: First JWST $α$-abundance Results in M31

Authors: David L. Nidever, Karoline Gilbert, Erik Tollerud, Charles Siders, Ivanna Escala, Carlos Allende Prieto, Verne Smith, Katia Cunha, Victor P. Debattista, Yuan-Sen Ting, Evan N. Kirby
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.04688
Pdf link: https://arxiv.org/pdf/2306.04688
Abstract
We present initial results from our JWST NIRSpec program to study the $\alpha$-abundances in the M31 disk. The Milky Way has two chemically-defined disks, the low-$\alpha$ and high-$\alpha$ disks, which are closely related to the thin and thick disks, respectively. The origin of the two populations and the $\alpha$-bimodality between them is not entirely clear, although there are now several models that can reproduce the observed features. To help constrain the models and discern the origin, we have undertaken a study of the chemical abundances of the M31 disk using JWST NIRSpec, in order to determine whether stars in M31's disk also show an $\alpha$-abundance bimodality. Approximately 100 stars were observed in our single NIRSpec field at a projected distance of 18 kpc from the M31 center. The 1-D extracted spectra have an average signal-to-noise ratio of 85 leading to statistical metallicity precision of 0.016 dex, $\alpha$-abundance precision of 0.012 dex, and a radial velocity precision 8 km/s. The initial results indicate that, in contrast to the Milky Way, there is no $\alpha$-bimodality in the M31 disk, and no low-$\alpha$ sequence. The entire stellar population falls along a single chemical sequence very similar to the MW's high-alpha component which had a high star formation rate. While this is somewhat unexpected, the result is not that surprising based on other studies that found the M31 disk has a larger velocity dispersion than the MW and is dominated by a thick component. M31 has had a more active accretion and merger history than the MW which might explain the chemical differences.

DELVE 6: An Ancient, Ultra-Faint Star Cluster on the Outskirts of the Magellanic Clouds

Authors: W. Cerny, A. Drlica-Wagner, T. S. Li, A. B. Pace, K. A. G. Olsen, N. E. D. Noël, R. P. van der Marel, J. L. Carlin, Y. Choi, D. Erkal, M. Geha, D. J. James, C. E. Martínez-Vázquez, P. Massana, G. E. Medina, A. E. Miller, B. Mutlu-Pakdil, D. L. Nidever, J. D. Sakowska, G. S. Stringfellow, J. A. Carballo-Bello, P. S. Ferguson, N. Kuropatkin, S. Mau, E. J. Tollerud, A. K. Vivas (DELVE Collaboration)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.04690
Pdf link: https://arxiv.org/pdf/2306.04690
Abstract
We present the discovery of DELVE 6, an ultra-faint stellar system identified in the second data release of the DECam Local Volume Exploration (DELVE) survey. Based on a maximum-likelihood fit to its structure and stellar population, we find that DELVE 6 is an old ($\tau > 9.8$ Gyr, at 95% confidence) and metal-poor ($\rm [Fe/H] < -1.17$ dex, at 95% confidence) stellar system with an absolute magnitude of $M_V = -1.5^{+0.4}{-0.6}$ mag and an azimuthally-averaged half-light radius of $r{1/2} =10^{+4}{-3}$ pc. These properties are consistent with the population of ultra-faint star clusters uncovered by recent surveys. Interestingly, DELVE 6 is located at an angular separation of $\sim 10\deg$ from the center of the Small Magellanic Cloud (SMC), corresponding to a three-dimensional physical separation of $\sim 20$ kpc given the system's observed distance ($D{\odot} = 80$ kpc). This also places the system $\sim 35$ kpc from the center of the Large Magellanic Cloud (LMC), lying within recent constraints on the size of the LMC's dark matter halo. We tentatively measure the proper motion of DELVE 6 using data from $\textit{Gaia}$, which we find supports a potential association between the system and the LMC/SMC. Although future kinematic measurements will be necessary to determine its origins, we highlight that DELVE 6 may represent only the second or third ancient ($\tau > 9$ Gyr) star cluster associated with the SMC, or one of fewer than two dozen ancient clusters associated with the LMC. Nonetheless, we cannot currently rule out the possibility that the system is a distant Milky Way halo star cluster.

Soft X-ray emission from warm gas in IllustrisTNG circum-cluster environments

Authors: Celine Gouin, Massimiliano Bonamente, Daniela Galarraga-Espinosa, Stephen Walker, Mohammad Mirakhor
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.04694
Pdf link: https://arxiv.org/pdf/2306.04694
Abstract
Context. Whereas X-ray clusters are extensively used for cosmology, their idealistic modelling, through the hypotheses of spherical symmetry and hydrostatic equilibrium, are more and more being questioned. Along these lines, the soft X-ray emission detected in tens of clusters with ROSAT was found to be higher than what expected from the idealistic hot gas modelling, pointing to our incomplete understanding of these objects. Aims. Given that cluster environments are at the interface between the hot intra-cluster medium (ICM), warm circum-galactic medium (WCGM) and warm-hot intergalactic medium (WHIM), we aim to explore the relative soft X-ray emission of different gas phases in circum-cluster environments. Method. By using the most massive halos in IllustrisTNG at z=0, we have predicted the hydrodynamical properties of the gas from cluster centers to their outskirts (5 R200), and modelled their X-ray radiation for various plasma phases. Results. First, we found that the radial profile of temperature, density, metallicity and clumpiness of the ICM are in good agreement with recent X-ray observations of clusters. Secondly, we have developed a method to predict the radial profile of soft X-ray emission in different bands, the column density of ions and the X-ray absorption lines (O VIII, O VII, Ne IX, and Ne IX) of warm-hot gas inside and around clusters. Conclusion. The warm gas (in the form of both WCGM and WHIM gas) is a strong emitter in soft X-ray bands, and is qualitatively consistent with the observational measurements. Our results suggest that the cluster soft excess is induced by the thermal emission of warm gas in the circum-cluster environments.

Multimessenger Emission from the Accretion Induced Collapse of White Dwarfs

Authors: Luís Felipe Longo Micchi, David Radice, Cecilia Chirenti
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2306.04711
Pdf link: https://arxiv.org/pdf/2306.04711
Abstract
We present fully general-relativistic three-dimensional numerical simulations of accretion-induced collapse (AIC) of white dwarfs (WDs). We evolve three different WD models (nonrotating, rotating at 80% and 99% of the Keplerian mass shedding limit) that collapse due to electron capture. For each of these models, we provide a detailed analysis of their gravitational waves (GWs), neutrinos and electromagnetic counterpart and discuss their detectability. Our results suggest that fast rotating AICs could be detectable up to a distance of 8 Mpc with third-generation GW observatories, and up to 1 Mpc with LIGO. AIC progenitors are expected to have large angular momentum due to their accretion history, which is a determining factor for their stronger GW emission compared to core-collapse supernovae (CCSNe). Regarding neutrino emission, we found no significant difference between AICs and CCSNe. In the electromagnetic spectrum, we find that AICs are two orders of magnitude fainter than type Ia supernovae. Our work places AICs as realistic targets for future multimessenger searches with third generation ground-based GW detectors.

SN 2023ixf in Messier 101: Photo-ionization of Dense, Close-in Circumstellar Material in a Nearby Type II Supernova

Authors: W. V. Jacobson-Galan, L. Dessart, R. Margutti, R. Chornock, R. J. Foley, C. D. Kilpatrick, D. O. Jones, K. Taggart, C. R. Angus, S. Bhattacharjee, L. A. Braff, D. Brethauer, A. J. Burgasser, F. Cao, C. M. Carlile, K. C. Chambers, D. A. Coulter, E. Dominguez-Ruiz, C. B. Dickinson, T. de Boer, A. Gagliano, C. Gall, H. Gao, E. L. Gates, S. Gomez, M. Guolo, M. R. J. Halford, J. Hjorth, M. E. Huber, M. N. Johnson, P. R. Karpoor, T. Laskar, N LeBaron, Z. Li, Y. Lin, S. D. Loch, P. D. Lynam, E. A. Magnier, P. Maloney, D.J. Matthews, M. McDonald, H.-Y. Miao, D. Milisavljevic, Y.-C. Pan, S. Pradyumna, C. L. Ransome, J. M. Rees, A. Rest, C. Rojas-Bravo, N. R. Sandford, L. Sandoval Ascencio, S. Sanjaripour, A. Savino, H. Sears, N. Sharei, S. J. Smartt, E. R. Softich, C. A. Theissen, S. Tinyanont, H. Tohfa, et al. (8 additional authors not shown)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.04721
Pdf link: https://arxiv.org/pdf/2306.04721
Abstract
We present UV/optical observations and models of supernova (SN) 2023ixf, a type II SN located in Messier 101 at 6.9 Mpc. Early-time ("flash") spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of H I, He I/II, C IV, and N III/IV/V with a narrow core and broad, symmetric wings arising from the photo-ionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for $\sim$8 days with respect to first light, at which time Doppler broadened features from the fastest SN ejecta form, suggesting a reduction in CSM density at $r \gtrsim 10^{15}$ cm. The early-time light curve of SN2023ixf shows peak absolute magnitudes (e.g., $M_{u} = -18.6$ mag, $M_{g} = -18.4$ mag) that are $\gtrsim 2$ mag brighter than typical type II supernovae, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light curve and multi-epoch spectral models from the non-LTE radiative transfer code CMFGEN and the radiation-hydrodynamics code HERACLES suggests dense, solar-metallicity, CSM confined to $r = (0.5-1) \times 10^{15}$ cm and a progenitor mass-loss rate of $\dot{M} = 10^{-2}$ M$_{\odot}$yr$^{-1}$. For the assumed progenitor wind velocity of $v_w = 50$ km s$^{-1}$, this corresponds to enhanced mass-loss (i.e., ``super-wind'' phase) during the last $\sim$3-6 years before explosion.

2021 occultations and transits of Linus orbiting (22) Kalliope: I. Polygonal and `cliptracing' algorithm

Authors: M. Brož, J. Ďurech, M. Ferrais, H.-J. Lee, M.-J. Kim, D.-G. Roh, H.-S. Yim, E. Jehin, A. Burdanov, J. de Wit, P. Fatka, J. Hanuš, B. Carry
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.04768
Pdf link: https://arxiv.org/pdf/2306.04768
Abstract
The satellite Linus orbiting the main-belt asteroid (22) Kalliope exhibited occultation and transit events in late 2021. A photometric campaign was organized and observations were taken by the TRAPPIST-South, SPECULOOS-Artemis, OWL-Net, and BOAO telescopes, with the goal to constrain models of this system. Our dynamical model is complex, with multipoles (up to the order $\ell = 2$), internal tides, and external tides. The model was constrained by astrometry (spanning 2001--2021), occultations, adaptive-optics imaging, calibrated photometry, as well as relative photometry. Our photometric model was substantially improved. A new precise (${<},0.1,{\rm mmag}$) light curve algorithm was implemented, based on polygon intersections, which are computed exactly -- by including partial eclipses and partial visibility of polygons. Moreover, we implemented a `cliptracing' algorithm, based again on polygon intersections, in which partial contributions to individual pixels are computed exactly. Both synthetic light curves and synthetic images are then very smooth. Based on our combined solution, we confirmed the size of Linus, $(28\pm 1),{\rm km}$. However, this solution exhibits some tension between the light curves and the PISCO speckle-interferometry dataset. In most solutions, Linus is darker than Kalliope, with the albedos $A_{\rm w} = 0.40$ vs. $0.44$. This is confirmed on deconvolved images. A~~detailed revision of astrometric data allowed us to revise also the $J_2 \equiv -C_{20}$ value of Kalliope. Most importantly, a~~homogeneous body is excluded. For a differentiated body, two solutions exist: low-oblateness ($C_{20} \simeq -0.12$), with a~spherical iron core, and alternatively, high-oblateness ($C_{20} \simeq -0.22$) with an elongated iron core. These correspond to the low- and high-energy collisions, respectively, studied by means of SPH simulations in our previous work.

Double SSA Spectrum and Magnetic Field Strength of the FSRQ 3C 454.3

Authors: Hyeon-Woo Jeong (1 and 2), Sang-Sung Lee (1 and 2), Whee Yeon Cheong (1 and 2), Jae-Young Kim (3 and 4), Jee Won Lee (2), Sincheol Kang (2), Sang-Hyun Kim (1 and 2), B. Rani (5 and 2 and 6), Jongho Park (2), Mark A. Gurwell (7) ((1) Astronomy and Space Science, University of Science and Technology, Republic of Korea (2) Korea Astronomy and Space Science Institute, (3) Department of Astronomy and Atmospheric Sciences, Kyungpook National University, (4) Max-Planck-Institut für Radioastronomie, (5) NASA Goddard Space Flight Center, (6) Department of Physics, American University, (7) Center for Astrophysics | Harvard & Smithsonian)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.04888
Pdf link: https://arxiv.org/pdf/2306.04888
Abstract
We present the results of a radio multi-frequency ($\rm 3-340~~GHz$) study of the blazar 3C~~454.3. After subtracting the quiescent spectrum corresponding to optically thin emission, we found two individual synchrotron self-absorption (SSA) features in the wide-band spectrum. The one SSA had a relatively low turnover frequency ($\nu_{\rm m}$) in the range of $\rm 3-37~~GHz$ (lower $\nu_{\rm m}$ SSA spectrum, LSS), and the other one had a relatively high $\nu_{\rm m}$ of $\rm 55-124~~GHz$ (higher $\nu_{\rm m}$ SSA spectrum, HSS). Using the SSA parameters, we estimated magnetic field strengths at the surface where optical depth $\tau=1$. The estimated magnetic field strengths were $\rm >7~~mG$ and $\rm >0.2~~mG$ for the LSS and HSS, respectively. The LSS emitting region was magnetically dominated before the June 2014 $\gamma$-ray flare. The quasi-stationary component (C), $\sim 0.6~{\rm mas}$ apart from the 43 GHz radio core, became brighter than the core with decreasing observing frequency, and we found that component C was related to the LSS. A decrease in jet width was found near component C. As a moving component, K14 approached component C, and the flux density of the component was enhanced while the angular size decreased. The high intrinsic brightness temperature in the fluid frame was obtained as $T_{\rm B, int} \approx (7.0\pm1.0) \times 10^{11}~{\rm K}$ from the jet component after the 2015 August $\gamma$-ray flare, suggesting that component C is a high-energy emitting region. The observed local minimum of jet width and re-brightening behavior suggest a possible recollimation shock in component C.

Investigating the OH-H2 relation in diffuse Galactic clouds

Authors: Katherine Rawlins, Bhaswati Mookerjea
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.05213
Pdf link: https://arxiv.org/pdf/2306.05213
Abstract
We investigate the correlation between OH and H2 column densities in diffuse Galactic clouds, in order to identify potential molecular tracers of interstellar H2. For this, we analyse near-UV spectra extracted from the ESO/VLT archives towards seventeen sightlines (five of them new) with known N(H2), along with nine sightlines with no H2 information. N(OH) shows only marginal correlation with N(H2) (10$^{20}$ to 2 x 10$^{21}$ cm$^{-2}$), at the 95 per cent confidence level. We use orthogonal distance regression analysis to obtain N(OH)/N(H2) = (1.32+/-0.15) x 10$^{-7}$, which is ~ 33 per cent higher than the previous estimates based on near-UV data. We also obtain N(CH)/N(H2) = (3.83+/-0.23) x 10$^{-8}$ and a significant correlation between N(OH) and N(CH), with N(OH) = (2.61+/-0.19) x N(CH), both of which are consistent with previous results. Comparison with predictions of numerical models indicate that OH absorption arises from diffuse gas (nH ~ 50 cm$^{-3}$) illuminated by radiation fields ~ 0.5-5 G0, while CH is associated with higher density of 500 cm$^{-3}$. We posit that the apparent dichotomy in the properties of the diffuse clouds giving rise to OH and CH absorption could be due to either (a) the presence of multiple spectroscopically unresolved clouds along the line-of-sight, or, (b) density gradients along the line-of-sight within a single cloud.

by olozhika (Xing Yuchen).

2023-06-09

New submissions for Fri, 19 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 5papers

ALMA and Keck analysis of Fomalhaut field sources: JWST's Great Dust Cloud is a background object

Authors: Grant M. Kennedy, Joshua B. Lovell, Paul Kalas, Michael P. Fitzgerald
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.10480
Pdf link: https://arxiv.org/pdf/2305.10480
Abstract
At 7.7 pc, the A-type star Fomalhaut hosts a bright debris disk with multiple radial components. The disk is eccentric and misaligned, strongly suggesting that it is sculpted by interaction with one or more planets. Compact sources are now being detected with JWST, suggesting that new planet detections may be imminent. However, to confirm such sources as companions, common proper motion with the star must be established, as with unprecedented sensitivity comes a high probability that planet candidates are actually background objects. Here, ALMA and Keck observations of Fomalhaut are found to show significant emission at the same sky location as multiple compact sources in JWST MIRI coronagraphic observations, one of which has been dubbed the "Great Dust Cloud" because it lies within the outer belt. Since the ground-based data were obtained between 6 to 18 years prior to the JWST observations, these compact sources are unlikely to be common proper motion companions to Fomalhaut. More generally, this work illustrates that images collected at a range of wavelengths can be valuable for rejecting planet candidates uncovered via direct imaging with JWST.

Searching for Intragroup Light in Deep U-band Imaging of the COSMOS Field

Authors: Tyler McCabe, Caleb Redshaw, Lillian Otteson, Rogier A. Windhorst, Rolf A. Jansen, Seth H. Cohen, Timothy Carleton, Sanchayeeta Borthakur, Teresa A. Ashcraft, Anton M. Koekemoer, Russell E. Ryan, Mario Nonino, Diego Paris, Andrea Grazian, Andriano Fontana, Emanuele Giallongo, Roberto Speziali, Vincenzo Testa, Konstantina Boutsia, Robert W. O'Connell, Michael J. Rutkowski, Claudia Scarlata, Harry I. Teplitz, Xin Wang, Marc Rafelski, Norman A. Grogin, Ray A. Lucas
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.10516
Pdf link: https://arxiv.org/pdf/2305.10516
Abstract
We present the results of deep, ground based U-band imaging with the Large Binocular Telescope of the Cosmic Evolution Survey (COSMOS) field as part of the near-UV imaging program, UVCANDELS. We utilize a seeing sorted stacking method along with night-to-night relative transparency corrections to create optimal depth and optimal resolution mosaics in the U-band, which are capable of reaching point source magnitudes of AB 26.5 mag at 3 sigma. These ground based mosaics bridge the wavelength gap between the HST WFC3 F27W and ACS F435W images and are necessary to understand galaxy assembly in the last 9-10 Gyr. We use the depth of these mosaics to search for the presence of U-band intragroup light (IGrL) beyond the local Universe. Regardless of how groups are scaled and stacked, we do not detect any U-band IGrL to unprecedented U-band depths of 29.1-29.6 mag/arcsec2, which corresponds to an IGrL fraction of less than 1% of the total group light. This stringent upper limit suggests that IGrL does not contribute significantly to the Extragalactic Background Light at short wavelengths. Furthermore, the lack of UV IGrL observed in these stacks suggests that the atomic gas observed in the intragroup medium (IGrM) is likely not dense enough to trigger star formation on large scales. Future studies may detect IGrL by creating similar stacks at longer wavelengths or by pre-selecting groups which are older and/or more dynamically evolved similar to past IGrL observations of compact groups and loose groups with signs of gravitational interactions.

Low-period spacing core-helium burning giants: `hot subdwarf analogues'?

Authors: S. Hekker, Y. Elsworth, T.A.M. Braun, S. Basu
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.10578
Pdf link: https://arxiv.org/pdf/2305.10578
Abstract
Global stellar oscillations probe the internal structure of stars. In low- to intermediate-mass red giants, these oscillations provide signatures from both the outer regions of the star as well as from the core. These signatures are imprinted in e.g. the frequency of maximum oscillation power, and in the differences in periods of non-radial oscillations (period spacings), respectively. In core helium burning giants with masses below about 1.7 solar masses, i.e. stars that have gone through a helium flash, the asymptotic period spacings take values of about 220 -350 s at frequency of maximum oscillation power of $\sim$30-50 $\mu$Hz. A set of stars with asymptotic period spacings lower than about 200 s at similar frequencies separations has recently been discovered by Elsworth and collaborators. In this work, we present a hypothesis for the formation scenario of these stars. We find that these stars can be the result of a mass-loss event at the end of the red-giant branch phase of stars massive enough to not have a degenerate core, i.e. one of the scenarios to form hot subdwarf stars. Therefore, these stars can be classified as `hot subdwarf analogues'. Interestingly, if mass loss continues gradually during the core helium burning phase, these stars turn hotter and denser, and could, therefore, be hot subdwarf progenitors as they shed more of their envelope.

HI Self-absorption toward the Cygnus X North: From Atomic Filament to Molecular Filament

Authors: Chong Li, Keping Qiu, Di Li, Hongchi Wang, Yue Cao, Junhao Liu, Yuehui Ma, Chenglin Yang
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.10795
Pdf link: https://arxiv.org/pdf/2305.10795
Abstract
Using the HI self-absorption data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we perform a study of the cold atomic gas in the Cygnus-X North region. The most remarkable HI cloud is characterized by a filamentary structure, associated in space and in velocity with the principle molecular filament in the Cygnus-X North region. We investigate the transition from the atomic filament to the molecular filament. We find that the HII regions Cygnus OB2 and G081.920+00.138 play a critical role in compressing and shaping the atomic Cygnus-X North filament, where the molecular filament subsequently forms. The cold HI in the DR21 filament has a much larger column density (N(HI) $\sim$ 1 $\times$ 10$^{20}$ cm$^{-2}$) than the theoretical value of the residual atomic gas ($\sim$ 1 $\times$ 10$^{19}$ cm$^{-2}$), suggesting that the HI-to-H$_2$ transition is still in progress. The timescale of the HI-to-H$_2$ transition is estimated to be 3 $\times$ 10$^{5}$ yr, which approximates the ages of massive protostars in the Cygnus-X North region. This implies that the formation of molecular clouds and massive stars may occur almost simultaneously in the DR21 filament, in accord with a picture of rapid and dynamic cloud evolution.

Equilibrium dynamical models for the Large Magellanic Cloud

Authors: Nikolay Kacharov, Maria-Rosa L. Cioni
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.10980
Pdf link: https://arxiv.org/pdf/2305.10980
Abstract
The Large Magellanic Cloud (LMC) has a complex dynamics driven by both internal and external processes. The external forces are due to tidal interactions with the Small Magellanic Cloud and the Milky Way, while internally its dynamics mainly depends on the stellar, gas, and dark matter mass distributions. Despite the overall complexity of the system, very often simple physical models can give us important insights about the main driving factors. Here we focus on the internal forces and attempt to model the proper motions of $\sim10^6$ stars in the LMC as measured by Gaia Data Release 3 with an axisymmetric dynamical model, based on the Jeans equations. We test both cored and cusped spherical Navarro-Frenk-White dark matter halos to fit the LMC gravitational potential. We find that this simple model is very successful at selecting a clean sample of genuine LMC member stars and predicts the geometry and orientation of the LMC with respect to the observer within the constraint of axisymmetry. Our Jeans dynamical models describe well the rotation profile and the velocity dispersion of the LMC stellar disc, however they fail to describe the motions of the LMC bar, which is a non-axisymmetric feature dominating the central region. We plan a triaxial Schwarzschild approach as a next step for the dynamical modelling of the LMC.

by olozhika (Xing Yuchen).

2023-05-19

New submissions for Wed, 14 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 3papers

Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life

Authors: William Bains, Janusz J. Petkowski, Sara Seager
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.07358
Pdf link: https://arxiv.org/pdf/2306.07358
Abstract
Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50-100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as "uninhabitable", and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there.

Excited Hydroxyl Outflow in the High-Mass Star-Forming Region G34.26+0.15

Authors: W. S. Tan, (1,2), E. D. Araya (1,3), C. Rigg (4), P. Hofner (3,5), S. Kurtz (6), H. Linz (7), V. Rosero (5) ((1) Physics Department, Western Illinois University, Macomb, IL, USA, (2) National University of Singapore, 21 Lower Kent Ridge Rd, Singapore 119077, (3) New Mexico Institute of Mining and Technology, Physics Department, Socorro, NM, USA, (4) Southeastern High School, 90 W Green St, Augusta, IL, USA, (5) National Radio Astronomy Observatory, Socorro, NM, USA, (6) Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antig. Carr. a Pátzcuaro 8701, 58089, Morelia, Michoacán, México, (7) Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany.)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.07394
Pdf link: https://arxiv.org/pdf/2306.07394
Abstract
G34.26+0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hyper-compact HII regions and a prototypical cometary ultra-compact HII region. Previous high-sensitivity single dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blue-shifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at $\sim 2$" scales, and it is coincident with one of the bright ionized cores of the cometary HII region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultra-compact HII region.

Detecting Fast Radio Bursts with Spectral Structure using the Continuous Forward Algorithm

Authors: Pravir Kumar, Barak Zackay, Casey J. Law
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.07914
Pdf link: https://arxiv.org/pdf/2306.07914
Abstract
Detecting Fast Radio Bursts (FRBs) with frequency-dependent intensity remains a challenge, as existing search algorithms do not account for the spectral shape and might have resulted in non-detections. We propose a novel detection statistic, which we call the Kalman detector, that improves the sensitivity of FRB signal detection by incorporating spectral shape information. The detection statistic is based on an optimal matched filter, marginalizing over all possible intensity functions, weighted by a random walk probability distribution, considering some decorrelation bandwidth. Our analysis of previously detected FRBs demonstrates that the Kalman score provides a comparable yet independent source of information for bursts with significant spectral structure and the sensitivity improvement is of the order of 0-200%, with a median improvement of 20%. We also apply the Kalman detector to existing data from FRB 20201124A and detect two new repeat bursts which were previously missed. Furthermore, we suggest a practical implementation for real-time surveys by employing a low significance soft-trigger from initial integration-based detection algorithms. The Kalman detector has the potential to significantly enhance FRB detection capabilities and enable new insights into the spectral properties of these enigmatic astrophysical phenomena.

by olozhika (Xing Yuchen).

2023-06-15

New submissions for Mon, 15 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 6papers

Efficient radial migration by giant molecular clouds in the first several hundred Myr after the stellar birth

Authors: Yusuke Fujimoto, Shu-ichiro Inutsuka, Junichi Baba
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.07050
Pdf link: https://arxiv.org/pdf/2305.07050
Abstract
Stars in the Galactic disc, including the Solar system, have deviated from their birth orbits and have experienced radial mixing and vertical heating. By performing hydrodynamical simulations of a galactic disc, we investigate how much tracer particles, which are initially located in the disc to mimic newborn stars and the thin and thick disc stars, are displaced from initial near-circular orbits by gravitational interactions with giant molecular clouds (GMCs). To exclude the influence of other perturbers that can change the stellar orbits, such as spiral arms and the bar, we use an axisymmetric form for the entire galactic potential. First, we investigate the time evolution of the radial and vertical velocity dispersion $\sigma_R$ and $\sigma_z$ by comparing them with a power law relation of $\sigma \propto t^{\beta}$. Although the exponents $\beta$ decrease with time, they keep large values of 0.3 $\sim$ 0.6 for 1 Gyr, indicating fast and efficient disc heating. Next, we find that the efficient stellar scattering by GMCs also causes a change in angular momentum for each star and, therefore, radial migration. This effect is more pronounced in newborn stars than old disc stars; nearly 30 per cent of stars initially located on the galactic mid-plane move more than 1 kpc in the radial direction for 1 Gyr. The dynamical heating and radial migration drastically occur in the first several hundred Myr. As the amplitude of the vertical oscillation increases, the time spent in the galactic plane, where most GMCs are distributed, decreases, and the rate of an increase in the heating and migration slows down.

Multi log-normal density structure in Cygnus-X molecular clouds: A fitting for N-PDF without power-law

Authors: Takeru Murase, Toshihiro Handa, Ren Matsusaka, Yoshito Shimajiri, Masato I.N. Kobayashi, Mikito Kohno, Junya Nishi, Norimi Takeba, Yosuke Shibata
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.07094
Pdf link: https://arxiv.org/pdf/2305.07094
Abstract
We studied the H$_2$ column density probability distribution function (N-PDF) based on molecular emission lines using the Nobeyama 45-m Cygnus X CO survey data. Using the DENDROGRAM and SCIMES algorithms, we identified 124 molecular clouds in the $^{13}$CO data. From these identified molecular clouds, an N-PDF was constructed for 11 molecular clouds with an extent of more than 0.4 deg$^2$. From the fitting of the N-PDF, we found that the N-PDF could be well-fitted with one or two log-normal distributions. These fitting results provided an alternative density structure for molecular clouds from a conventional picture. We investigated the column density, dense molecular cloud cores, and radio continuum source distributions in each cloud and found that the N-PDF shape was less correlated with the star-forming activity over a whole cloud. Furthermore, we found that the log-normal N-PDF parameters obtained from the fitting showed two impressive features. First, the log-normal distribution at the low-density part had the same mean column density ($\sim$ 10$^{21.5}$ cm$^{-2}$) for almost all the molecular clouds. Second, the width of the log-normal distribution tended to decrease with an increasing mean density of the structures. These correlations suggest that the shape of the N-PDF reflects the relationship between the density and turbulent structure of the whole molecular cloud but is less affected by star-forming activities.

First detection of deuterated methylidyne (CD) in the interstellar medium

Authors: Arshia M. Jacob, Karl M. Menten, Friedrich Wyrowski, Olli Sipilä
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.07143
Pdf link: https://arxiv.org/pdf/2305.07143
Abstract
While the abundance of elemental deuterium is relatively low (D/H ~ a few 1E-5), orders of magnitude higher D/H abundance ratios have been found for many interstellar molecules, enhanced by deuterium fractionation. In cold molecular clouds (T < 20K) deuterium fractionation is driven by the H2D+ ion, whereas at higher temperatures (T > 20-30K) gas-phase deuteration is controlled by reactions with CH2D+ and C2HD+. While the role of H2D+ in driving cold interstellar deuterium chemistry is well understood, thanks to observational constraints from direct measurements of H2D+, deuteration stemming from CH2D+ is far less understood, caused by the absence of direct observational constraints of its key ions. Therefore, making use of chemical surrogates is imperative for exploring deuterium chemistry at intermediate temperatures. Formed at an early stage of ion-molecule chemistry, directly from the dissociative recombination of CH3+ (CH2D+), CH (CD) is an ideal tracer for investigating deuterium substitution initiated by reactions with CH2D+. This paper reports the first detection of CD in the interstellar medium, carried out using the APEX 12m telescope toward the widely studied low-mass protostellar system IRAS 16293-2422. Gas-phase chemical models reproducing the observed CD/CH abundance ratio of 0.016 suggests that it reflects `warm deuterium chemistry' (which ensues in moderately warm conditions of the interstellar medium) and illustrates the potential use of the CD/CH ratio in constraining the gas temperatures of the envelope gas clouds it probes.

Trajectories of Coronal Mass Ejection from Solar-type Stars

Authors: Fabian Menezes, Adriana Valio, Yuri Netto, Alexandre Araújo, Christina Kay, Merav Opher
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.07159
Pdf link: https://arxiv.org/pdf/2305.07159
Abstract
The Sun and other solar-type stars have magnetic fields that permeate their interior and surface, extends through the interplanetary medium, and is the main driver of stellar activity. Stellar magnetic activity affects physical processes and conditions of the interplanetary medium and orbiting planets. Coronal mass ejections (CMEs) are the most impacting of these phenomena in near-Earth space weather, and consist of plasma clouds, with magnetic field, ejected from the solar corona. Precisely predicting the trajectory of CMEs is crucial in determining whether a CME will hit a planet and impact its magnetosphere and atmosphere. Despite the rapid developments in the search for stellar CMEs, their detection is still very incipient. In this work we aim to better understand the propagation of CMEs by analysing the influence of initial parameters on CME trajectories, such as position, velocities, and stellar magnetic field's configuration. We reconstruct magnetograms for Kepler-63 (KIC 11554435) and Kepler-411 (KIC 11551692) from spot transit mapping, and use a CME deflection model, ForeCAT, to simulate trajectories of hypothetical CMEs launched into the interplanetary medium from Kepler-63 and Kepler-411. We apply the same methodology to the Sun, for comparison. Our results show that in general, deflections and rotations of CMEs decrease with their radial velocity, and increase with ejection latitude. Moreover, magnetic fields stronger than the Sun's, such as Kepler-63's, tend to cause greater CME deflections.

Large-scale Velocity-coherent Filaments in the SEDIGISM Survey: Association with Spiral Arms and Fraction of Dense Gas

Authors: Y. Ge, K. Wang, A. Duarte-Cabral, A. R. Pettitt, C. L. Dobbs, Á. Sánchez-Monge, K. R. Neralwar, J. S. Urquhart, D. Colombo, E. Durán-Camacho, H. Beuther, L. Bronfman, A. J. Rigby, D. Eden, S. Neupane, P. Barnes, T. Henning, A. Y. Yang
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.07353
Pdf link: https://arxiv.org/pdf/2305.07353
Abstract
Context. Filamentary structures in the interstellar medium are closely related to star formation. Dense gas mass fraction (DGMF) or clump formation efficiency in large-scale filaments possibly determine their hosting star formation activities. Aims. We aim to automatically identify large-scale filaments, characterize them, investigate their association with Galactic structures, and study their DGMFs. Methods. We use a modified minimum spanning tree (MST) algorithm to chain parsec-scale 13CO clumps previously extracted from the SEDIGISM (Structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) survey. The MST connects nodes in a graph such that the sum of edge lengths is minimum. Modified MST also ensures velocity coherence between nodes, so the identified filaments are coherent in position-position-velocity (PPV) space. Results. We generate a catalog of 88 large-scale ($>10pc$) filaments in the inner Galactic plane (with $-60^\circ < l < 18^\circ and $|b| < 0.5^\circ$). These SEDIGISM filaments are larger and less dense than MST filaments previously identified from the BGPS and ATLASGAL surveys. We find that eight of the filaments run along spiral arms and can be regarded as "bones" of the Milky Way. We also find three bones associated with the Local Spur in PPV space. By compiling 168 large-scale filaments with available DGMF across the Galaxy, an order of magnitude more than previously investigated, we find that DGMFs do not correlate with Galactic location, but bones have higher DGMFs than other filaments.

How do supernova remnants cool? -- I. Morphology, optical emission lines, and shocks

Authors: Ekaterina I. Makarenko (1), Stefanie Walch (1), Seamus D. Clarke (2), Daniel Seifried (1), Thorsten Naab (3), Pierre C. Nürnberger (1), Tim-Eric Rathjen (1) ((1) I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany, (2) Institute of Astronomy and Astrophysics, Academia Sinica, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, (3) Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.07652
Pdf link: https://arxiv.org/pdf/2305.07652
Abstract
Supernovae (SNe) inject $\sim 10^{51}$ erg in the interstellar medium, thereby shocking and heating the gas. A substantial fraction of this energy is later lost via radiative cooling. We present a post-processing module for the FLASH code to calculate the cooling radiation from shock-heated gas using collisional excitation data from MAPPINGS V. When applying this tool to a simulated SN remnant (SNR), we find that most energy is emitted in the EUV. However, optical emission lines ($[$O III$]$, $[$N II$]$, $[$S II$]$, H${\alpha}$, H${\beta}$) are usually best observable. Our shock detection scheme shows that [S II] and [N II] emissions arise from the thin shell surrounding the SNR, while [O III], H$\rm \alpha$, and H$\rm \beta$ originate from the volume-filling hot gas inside the SNR bubble. We find that the optical emission lines are affected by the SNR's complex structure and its projection onto the plane of the sky because the escaping line luminosity can be reduced by 10 -- 80% due to absorption along the line-of-sight. Additionally, the subtraction of contaminating background radiation is required for the correct classification of an SNR on the oxygen or sulphur BPT diagrams. The electron temperature and density obtained from our synthetic observations match well with the simulation but are very sensitive to the assumed metallicity.

by olozhika (Xing Yuchen).

2023-05-15

New submissions for Mon, 19 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 3papers

Betelgeuse: a Review

Authors: J. Craig Wheeler, Emmanouil Chatzopoulos
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.09449
Pdf link: https://arxiv.org/pdf/2306.09449
Abstract
Betelgeuse has fascinated people since they first looked at the sky. Here we present a contemporary summary of the observations and theory that lead to our understanding of Betelgeuse as a massive red supergiant doomed to collapse and explosion. At only ~200 parsecs from Earth, Betelgeuse can be spatially resolved yet uncertainties in its distance remain a critical impediment to deeper understanding. The surface of Betelgeuse is rent with a complex structure as deep convective eddies arise to the surface affecting most of its measured physical properties. Determination of the equatorial rotation velocity is critical since some current estimates indicate that Betelgeuse is rotating anomalously rapidly, a property that cannot be explained by single-star evolutionary models. Betelgeuse is also moving through space at relatively high velocity that indicates that it received a boost, likely via collective interaction with other stars in its birth cluster. A bow shock and other structure in the direction of the star's motion suggest that it has affected the organization of the circumstellar and interstellar medium. Betelgeuse varies in brightness on a variety of time scales with 200, 400 and 2000 days being prominent. Betelgeuse is probable to have been born in a binary system, and the high space velocity and apparent rotation have been related to binary star evolution. One possibility is that Betelgeuse underwent common envelope evolution culminating in a final merger with the core of a massive primary. Such merger models have been invoked to account for the anomalous rotation velocity. Betelgeuse underwent a Great Dimming in 2020 that received widespread attention. Explanations have focused on large cool spots on the surface and the expulsion of a cloud of dust that obscured the surface. We sketch the nature of the explosion to come and discuss perspectives for further research.

The Dark Neutral Medium is (Mostly) Molecular Hydrogen

Authors: Harvey Liszt, Maryvonne Gerin
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.09502
Pdf link: https://arxiv.org/pdf/2306.09502
Abstract
We acquired ALMA ground state absorption profiles of HCO+ and other molecules toward 33 extragalactic continuum sources seen toward the Galactic anticenter, deriving N(H2) = N(HCO+)/3x10^{-9}. We observed J=1-0 CO emission with the IRAM 30m in directions where HCO+ was newly detected. HCO+ absorption was detected in 28 of 33 new directions and CO emission along 19 of those 28. The 5 sightlines lacking detectable HCO+ have 3 times lower mean EBV and N(DNM). Binned in EBV, N(H2) and N(DNM) are strongly correlated and vary by factors of 50-100 over the observed range EBV~0.05-1 mag, while N(HI) varies by factors of only 2-3. On average N(DNM) and N(H2) are well matched, and detecting HCO+ absorption adds little/no H2 in excess of the previously inferred DNM. There are 5 cases where 2N(H2) < N(DNM)/2 indicates saturation of the HI emission. For sightlines with \WCO > 1 K-\kms the CO-H2 conversion factor N(H2)/\WCO\ = 2-3x10^{20}\pcc/K-\kms is higher than derived from studies of resolved clouds in gamma-rays. Our work sampled primarily atomic gas with a mean H2 fraction ~1/3, but the DNM is almost entirely molecular. CO fulfills its role as an H2 tracer when its emission is strong, but large-scale CO surveys are not sensitive to H2 columns associated with typical values N(DNM) = 2-6x10^{20}\pcc. Lower \XCO\ values from $\gamma$-ray studies arise in part from different definitions and usage. Sightlines with \WCO\ \ge 1 K-\kms\ represent 2/3 of the H2 detected in HCO+ and detecting 90% of the H2 would require detecting CO at levels \WCO~0.2-0.3 K-\kms For full abstract see the paper

Astrophysical Uncertainties in the Gravitational-Wave Background from Stellar-Mass Compact Binary Mergers

Authors: Leonard Lehoucq, Irina Dvorkin, Rahul Srinivasan, Clement Pellouin, Astrid Lamberts
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.09861
Pdf link: https://arxiv.org/pdf/2306.09861
Abstract
We investigate the Stochastic Gravitational Wave Background (SGWB) produced by merging binary black holes (BBHs) and binary neutron stars (BNSs) in the frequency ranges of LIGO/Virgo/Kagra and LISA. We develop three analytical models, that are calibrated to the measured local merger rates, and complement them with three population synthesis models based on the COSMIC code. We discuss the uncertainties, focusing on the impact of the BBH mass distribution, the effect of the metallicity of the progenitor stars and the time delay distribution between star formation and compact binary merger. We also explore the effect of uncertainties in binary stellar evolution on the background. For BBHs, our analytical models predict $\Omega_{GW}$ in the range $[4.10^{-10}-1.10^{-9}]$ (25 Hz) and $[1.10^{-12}-4.10^{-12}]$ (3 mHz), and between $[2.10^{-10}-2.10^{-9}]$ (25 Hz) and $[7.10^{-13}- 7.10^{-12}]$ (3 mHz) for our population synthesis models. This background is unlikely to be detected during the LIGO/Virgo/Kagra O4 run, but could be detectable with LISA. We predict about 10 BBH and no BNS mergers that could be individually detectable by LISA for a period of observation of 4 years. Our study provides new insights into the population of compact binaries and the main sources of uncertainty in the astrophysical SGWB.

by olozhika (Xing Yuchen).

2023-06-19

New submissions for Fri, 23 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 6papers

Interstellar Comets from Post-Main Sequence Systems as Tracers of Extrasolar Oort Clouds

Authors: W. Garrett Levine, Aster G. Taylor, Darryl Z. Seligman, Devin J. Hoover, Robert Jedicke, Jennifer B. Bergner, Gregory P. Laughlin
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.12464
Pdf link: https://arxiv.org/pdf/2306.12464
Abstract
Interstellar small bodies are unique probes into the histories of exoplanetary systems. One hypothesized class of interlopers are "Jurads," exo-comets released into the Milky Way during the post-main sequence as the thermally-pulsing asymptotic giant branch (AGB) host stars lose mass. In this study, we assess the prospects for the Legacy Survey of Space and Time (LSST) to detect a Jurad and examine whether such an interloper would be observationally distinguishable from exo-comets ejected during the (pre-)main sequence. Using analytic and numerical methods, we estimate the fraction of exo-Oort Cloud objects that are released from 1-8 solar mass stars during post-main sequence evolution. We quantify the extent to which small bodies are altered by the increased luminosity and stellar outflows during the AGB, finding that some Jurads may lack hypervolatiles and that stellar winds could deposit dust that covers the entire exo-comet surface. Next, we construct models of the interstellar small body reservoir for various size-frequency distribution slopes, characteristic sizes, and the total mass sequestered in the minor planets of exo-Oort Clouds. Even with the LSST's increased search volume compared to contemporary surveys, we find that detecting a Jurad is unlikely but not infeasible given the current understanding of (exo)planet formation.

An insight into Capella (alpha Aurigae): from the extent of core overshoot to its evolutionary history

Authors: E. Marini, C. Ventura, M. Tailo, P. Ventura, F. Dell'Agli, M. Castellani
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12753
Pdf link: https://arxiv.org/pdf/2306.12753
Abstract
The binary star alpha Aurigae (otherwise known as Capella) is extremely important to understand the core hydrogen and helium burning phases of the stars, as the primary star is likely evolving through the core helium burning phase, and the masses of the two components are 2.5 Msun and 2.6 Msun, which fall into a mass range for which the extention of the core overshoot during the main sequence phase is uncertain. We aim at deriving the extent of the core overshoot experienced during the core burning phases and testing the efficiency of the convective transport of energy in the external envelope, by comparing results from stellar evolution modelling with the results from the observations. We consider evolutionary tracks calculated on purpose for the present work, for the primary and secondary star of Capella. We determine the extent of the extra-mixing from the core during the main sequence evolution and the age of the system, by requiring that the effective temperatures and surface gravities of the model stars reproduce those derived from the observations at the same epoch. We further check consistency between the observed and predicted surface chemistry of the stars. Consistency between results from stellar evolution modelling and the observations of Capella is found when extra-mixing from the core is assumed, the extent of the extra-mixed zone being of the order of 0.25 H_P. The age of the system is estimated to be 710 Myr. These results allow to nicely reproduce the observed surface chemistry, particularly the recent determination of the 12C/13C ratio based on LBT (Large Binocular Telescope) and VATT (Vatican Advanced Technology Telescope) observations

Similar levels of deuteration in the pre-stellar core L1544 and the protostellar core HH211

Authors: K. Giers, S. Spezzano, P. Caselli, E. Wirström, O. Sipilä, J. E. Pineda, E. Redaelli, C. T. Bop, F. Lique
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.12775
Pdf link: https://arxiv.org/pdf/2306.12775
Abstract
In the centre of pre-stellar cores, deuterium fractionation is enhanced due to the low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to study the earliest stages of star formation. We analyse the deuterium fractionation of simple molecules, comparing the level of deuteration in the envelopes of the pre-stellar core L1544 in Taurus and the protostellar core HH211 in Perseus. We used single-dish observations of CCH, HCN, HNC, HCO$^+$, and their $^{13}$C-, $^{18}$O- and D-bearing isotopologues, detected with the Onsala 20m telescope. We derived the column densities and the deuterium fractions of the molecules. Additionally, we used radiative transfer simulations and results from chemical modelling to reproduce the observed molecular lines. We used new collisional rate coefficients for HNC, HN$^{13}$C, DNC, and DCN that consider the hyperfine structure of these molecules. We find high levels of deuteration for CCH (10%) in both sources, consistent with other carbon chains, and moderate levels for HCN (5-7%) and HNC (8%). The deuterium fraction of HCO$^+$ is enhanced towards HH211, most likely caused by isotope-selective photodissociation of C$^{18}$O. Similar levels of deuteration show that the process is likely equally efficient towards both cores, suggesting that the protostellar envelope still retains the chemical composition of the original pre-stellar core. The fact that the two cores are embedded in different molecular clouds also suggests that environmental conditions do not have a significant effect on the deuteration within dense cores. Radiative transfer modelling shows that it is necessary to include the outer layers of the cores to consider the effects of extended structures. Besides HCO$^+$ observations, HCN observations towards L1544 also require the presence of an outer diffuse layer where the molecules are relatively abundant.

Searching for dark matter substructure: a deeper wide-area community survey for Roman

Authors: Tansu Daylan, Simon Birrer
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.12864
Pdf link: https://arxiv.org/pdf/2306.12864
Abstract
We recommend a deeper extension to the High-Latitute Wide Area Survey planned to be conducted by the Nancy Grace Roman Space Telescope (\emph{Roman}). While this deeper-tier survey extension can support a range of astrophysical investigations, it is particularly well suited to characterize the dark matter substructure in galactic halos and reveal the microphysics of dark matter through gravitational lensing. We quantify the expected yield of \emph{Roman} for finding galaxy-galaxy-type gravitational lenses and motivate observational choices to optimize the \emph{Roman} core community surveys for studying dark matter substructure. In the proposed survey, we expect to find, on average, one strong lens with a characterizable substructure per \emph{Roman} tile (0.28 squared degrees), yielding approximately 500 such high-quality lenses. With such a deeper legacy survey, \emph{Roman} will outperform any current and planned telescope within the next decade in its potential to characterize the concentration and abundance of dark matter subhalos in the mass range 10$^7$-10$^{11}$,M$_{\odot}$.

Scattering Transparency of Clouds in Exoplanet Transit Spectra

Authors: Bhavesh Jaiswal, Tyler D. Robinson
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.12911
Pdf link: https://arxiv.org/pdf/2306.12911
Abstract
The presence of aerosols in an exoplanet atmosphere can veil the underlying material and can lead to a flat transmission spectrum during primary transit observations. In this work, we explore forward scattering effects from super-micron sized aerosol particles present in the atmosphere of a transiting exoplanet. We find that the impacts of forward scattering from larger aerosols can significantly impact exoplanet transits and the strength of these effects can be dependent on wavelength. In certain cloud configurations, the forward-scattered light can effectively pass through the clouds unhindered, thus rendering the clouds transparent. The dependence of the aerosol scattering properties on wavelength can then lead to a positive slope in the transit spectrum. These slopes are characteristically different from both Rayleigh and aerosol absorption slopes. As examples, we demonstrate scattering effects for both a rocky world and a hot Jupiter. In these models, the predicted spectral slopes due to forward scattering effects can manifest in the transit spectrum at the level of $\sim$10s to $\sim$100s of parts per million and, hence, could be observable with NASA's James Webb Space Telescope.

Star cluster formation and feedback in different environments of a Milky Way-like galaxy

Authors: Ahmad A. Ali, Clare L. Dobbs, Thomas J. R. Bending, Anne S. M. Buckner, Alex R. Pettitt
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12945
Pdf link: https://arxiv.org/pdf/2306.12945
Abstract
It remains unclear how galactic environment affects star formation and stellar cluster properties. This is difficult to address in Milky Way-mass galaxy simulations because of limited resolution and less accurate feedback compared to cloud-scale models. We carry out zoom-in simulations to re-simulate 100-300 pc regions of a Milky Way-like galaxy using smoothed particle hydrodynamics, including finer resolution (0.4 Msun per particle), cluster-sink particles, ray-traced photoionization from O stars, H$2$/CO chemistry, and ISM heating/cooling. We select $10^6$ Msun cloud complexes from a galactic bar, inner spiral arm, outer arm, and inter-arm region (in order of galactocentric radius), retaining the original galactic potentials. The surface densities of star formation rate and neutral gas follow $\Sigma{SFR} \propto \Sigma_{gas}^{1.3}$, with the bar lying higher up the relation than the other regions. However, the inter-arm region forms stars 2-3x less efficiently than the arm models at the same $\Sigma_{gas}$. The bar produces the most massive cluster, the inner arm the second, and the inter-arm the third. Almost all clusters in the bar and inner arm are small (radii < 5 pc), while 30-50 per cent of clusters in the outer arm and inter-arm have larger radii more like associations. Bar and inner arm clusters rotate at least twice as fast, on average, than clusters in the outer arm and inter-arm regions. The degree of spatial clustering also decreases from bar to inter-arm. Our results indicate that young massive clusters, potentially progenitors of globular clusters, may preferentially form near the bar/inner arm compared to outer arm/inter-arm regions.

by olozhika (Xing Yuchen).

2023-06-23

New submissions for Thu, 8 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

Uncovering axion-like particles in supernova gamma-ray spectra

Authors: Francesca Calore, Pierluca Carenza, Christopher Eckner, Maurizio Giannotti, Giuseppe Lucente, Alessandro Mirizzi, Francesco Sivo
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.03925
Pdf link: https://arxiv.org/pdf/2306.03925
Abstract
A future Galactic Supernova (SN) explosion can lead to a gamma-ray signal induced by ultralight Axion-Like Particles (ALPs) thermally produced in the SN core and converted into high-energy photons in the Galactic magnetic field. The detection of such a signal is in the reach of the Large Area Telescope aboard the \emph{Fermi} Gamma-Ray Space Telescope. The observation of gamma-ray emission from a future SN has a sensitivity to $g_{a\gamma}\gtrsim 4\times 10^{-13}$ GeV$^{-1}$ for a SN at fiducial distance of $10$ kpc and would allow us to reconstruct the ALP-photon coupling within a factor of $\sim2$, mainly due to the uncertainties on the modeling of the Galactic magnetic field.

The Formation of Magellanic System and the total mass of Large Magellanic Cloud

Authors: Jianling Wang, Francois Hammer, Yanbin Yang, Maria-Rosa L. Cioni
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.03944
Pdf link: https://arxiv.org/pdf/2306.03944
Abstract
The Magellanic Stream is unique to sample the MW potential from ~50 kpc to 300 kpc, and is also unique in constraining the LMC mass, an increasingly important question for the Local Group/Milky Way modeling. Here we compare strengths and weaknesses of the two types of models (tidal and ram-pressure) of the Magellanic Stream formation. I will present our modeling for the formation of the Magellanic System, including those of the most recent discoveries in the Stream, in the Bridge and at the outskirts of Magellanic Clouds. This model has been successful in predicting most recent observations in both properties of stellar and gas phase. It appears that it is an over-constrained model and provides a good path to investigate the Stream properties. In particular, this model requires a LMC mass significantly smaller than 110^{11} Msun

Three-Dimensional General-Relativistic Simulations of Neutrino-Driven Winds from Magnetized Proto-Neutron Stars

Authors: Dhruv K. Desai, Daniel M. Siegel, Brian D. Metzger
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2306.03973
Pdf link: https://arxiv.org/pdf/2306.03973
Abstract
Formed in the aftermath of a core-collapse supernova or neutron star merger, a hot proto-neutron star (PNS) launches an outflow driven by neutrino heating lasting for up to tens of seconds. Though such winds are considered potential sites for the nucleosynthesis of heavy elements via the rapid neutron capture process ($r$-process), previous work has shown that unmagnetized PNS winds fail to achieve the necessary combination of high entropy and/or short dynamical timescale in the seed nucleus formation region. We present three-dimensional general-relativistic magnetohydrodynamical (GRMHD) simulations of PNS winds which include the effects of a dynamically strong ($B \gtrsim 10^{15}$ G) dipole magnetic field. After initializing the magnetic field, the wind quickly develops a helmet-streamer configuration, characterized by outflows along open polar magnetic field lines and a ``closed'' zone of trapped plasma at lower latitudes. Neutrino heating within the closed zone causes the thermal pressure of the trapped material to rise in time compared to the polar outflow regions, ultimately leading to the expulsion of this matter from the closed zone on a timescale of $\sim$60 ms, consistent with the predictions of \citet{Thompson03}. The high entropies of these transient ejecta are still growing at the end of our simulations and are sufficient to enable a successful 2nd-peak $r$-process in at least a modest $\gtrsim 1%$ of the equatorial wind ejecta.

MOBSTER -- VII. Using light curves to infer magnetic and rotational properties of stars with centrifugal magnetospheres

Authors: I. D. Berry, M. E. Shultz, S. P. Owocki, A. ud-Doula
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.03990
Pdf link: https://arxiv.org/pdf/2306.03990
Abstract
Early-type B stars with strong magnetic fields and rapid rotation form centrifugal magnetospheres (CMs), as the relatively weak stellar wind becomes magnetically confined and centrifugally supported above the Kepler co-rotation radius. CM plasma is concentrated at and above the Kepler co-rotation radius at the intersection between the rotation and magnetic field axis. Stellar rotation can cause these clouds of material to intersect the viewer's line-of-sight, leading to photometric eclipses. However, for stars with strong ($\sim 10,{\rm kG}$) magnetic fields and rapid rotation, CMs can become optically thick enough for emission to occur via electron scattering. Using high-precision space photometry from a sample of stars with strong H$\alpha$ emission, we apply simulated light curves from the Rigidly Rotating Magnetosphere model to directly infer magnetic and rotational properties of these stars. By comparing the values inferred from photometric modelling to those independently determined by spectropolarimetry, we find that magnetic obliquity angle $\beta$, viewer inclination $i$ and critical rotation fraction $W$ can be approximately recovered for 3 of the 4 stars studied here. However, there are large discrepancies between the optical depth at the Kepler radius $\tau_{\rm K}$ expected from magnetometry, and the values required to match the observations. We show that $\tau_{\rm K}$ of order unity is needed to reasonably match the light curve morphology of our sample stars.

TOI-5678 b: A 48-day transiting Neptune-mass planet characterized with CHEOPS and HARPS

Authors: S. Ulmer-Moll, H. P. Osborn, A. Tuson, J. A. Egger, M. Lendl, P. Maxted, A. Bekkelien, A. E. Simon, G. Olofsson, V. Adibekyan, Y. Alibert, A. Bonfanti, F. Bouchy, A. Brandeker, M. Fridlund, D. Gandolfi, C. Mordasini, C. M. Persson, S. Salmon, L. M. Serrano, S. G. Sousa, T. G. Wilson, M. Rieder, J. Hasiba, J. Asquier, D. Sicilia, I. Walter, R. Alonso, G. Anglada, D. Barrado y Navascues, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, X. Bonfils, L. Borsato, C. Broeg, T. Bárczy, J. Cabrera, S. Charnoz, M. Cointepas, A. Collier Cameron, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D. S. Demangeon, B.-O. Demory, X. Dumusque, D. Ehrenreich, N.L. Eisner, A. Erikson, A. Fortier, L. Fossati, M. Gillon, N. Grieves, M. Güdel, J. Hagelberg, et al. (33 additional authors not shown)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.04295
Pdf link: https://arxiv.org/pdf/2306.04295
Abstract
A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few dozen of these planets have a precise radius measurement. Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and for shedding light on the formation and evolution of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are unaltered by intense stellar irradiation and tidal effects. We identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as duo-transit events. To solve the orbital periods of TESS duo-transit candidates, we use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. We also collect spectroscopic observations with CORALIE and HARPS in order to confirm the planetary nature and measure the mass of the candidates. We report the discovery of a warm transiting Neptune-mass planet orbiting TOI-5678. After four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet. TOI-5678 b has a mass of 20 (+-4) Me and a radius of 4.91 (+-0.08 Re) . Using interior structure modeling, we find that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2 (+1.7, -1.3) Me. TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar insolation (11 Se). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars are suitable targets to study the atmospheric composition of cooler gas giants.

Framework for Multi-messenger Inference from Neutron Stars: Combining Nuclear Theory Priors

Authors: Praveer Tiwari, Dake Zhou, Bhaskar Biswas, Michael McNeil Forbes, Sukanta Bose
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Data Analysis, Statistics and Probability (physics.data-an)
Arxiv link: https://arxiv.org/abs/2306.04386
Pdf link: https://arxiv.org/pdf/2306.04386
Abstract
We construct an efficient parameterization of the pure neutron-matter equation of state (EoS) that incorporates the uncertainties from both chiral effective field theory ($\chi$EFT) and phenomenological potential calculations. This parameterization yields a family of EoSs including and extending the forms based purely on these two calculations. In combination with an agnostic inner core EoS, this parameterization is used in a Bayesian inference pipeline to obtain constraints on the e os parameters using multi-messenger observations of neutron stars. We specifically considered observations of the massive pulsar J0740+6620, the binary neutron star coalescence GW170817, and the NICER pulsar J0030+0451. Constraints on neutron star mass-radius relations are obtained and compared. The Bayes factors for the different EoS models are also computed. While current constraints do not reveal any significant preference among these models, the framework developed here may enable future observations with more sensitive detectors to discriminate them.

Implications of a Possible Spectral Structure of Cosmic-ray Protons Unveiled by the DAMPE

Authors: Lin Nie, Yang Liu, Zejun Jiang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.04558
Pdf link: https://arxiv.org/pdf/2306.04558
Abstract
The recent observations revealed that the cosmic-ray (CR) proton spectrum showed a complex structure: the hardening at $\rm \sim 200,GeV$ and softening at $\rm \sim 10,TeV$. However, so far the physical origins of this spectral feature remain strongly debated. In this work, we simulate the acceleration of cosmic-ray protons in a nearby Supernova remnant (SNR) by solving numerically the hydrodynamic equations and the equation for the quasi-isotropic CR momentum distribution in the spherically symmetrical case to derive the spectrum of protons injected into the interstellar medium (ISM), and then simulate the propagation process of those accelerated CR particles to calculate the proton fluxes reaching the Earth. Besides, we use the DRAGON numerical code to calculate the large-scale cosmic-ray proton spectrum. Our simulated results are in good agreement with the observed data (including the observed data of proton fluxes and dipole anisotropy). We conclude that the spectral feature of cosmic-ray protons in this energy band may originate from the superposition of the distribution from the nearby SNR and background diffusive cosmic-ray component. We find that the release of particles from this nearby SNR has a time delay. Besides, it can be found that the nonlinear response of energetic particles, release time of CR protons, and age of the local SNR can leave strong signatures in the spectrum of the resulting CR proton fluxes.

by olozhika (Xing Yuchen).

2023-06-08

New submissions for Tue, 23 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 15papers

The growth of the gargantuan black holes powering high-redshift quasars and their impact on the formation of early galaxies and protoclusters

Authors: Jake S. Bennett, Debora Sijacki, Tiago Costa, Nicolas Laporte, Callum Witten
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.11932
Pdf link: https://arxiv.org/pdf/2305.11932
Abstract
High-redshift quasars ($z\gtrsim6$), powered by black holes (BHs) with large inferred masses, imply rapid BH growth in the early Universe. The most extreme examples have inferred masses of $\sim ! 10^9,$M$\odot$ at $z = 7.5$ and $\sim ! 10^{10},$M$\odot$ at $z = 6.3$. Such dramatic growth via gas accretion likely leads to significant energy input into the quasar host galaxy and its surroundings, however few theoretical predictions of the impact of such objects currently exist. We present zoom-in simulations of a massive high-redshift protocluster, with our fiducial FABLE model incapable of reproducing the brightest quasars. With modifications to this model to promote early BH growth, such as earlier seeding and mildly super-Eddington accretion, such `gargantuan' BHs can be formed. With this new model, simulated host dust masses and star formation rates are in good agreement with existing JWST and ALMA data from ultraluminous quasars. We find the quasar is often obscured as it grows, and that strong, ejective feedback is required to have a high probability of detecting the quasar in the rest-frame UV. Fast and energetic quasar-driven winds expel metal-enriched gas, leading to significant metal pollution of the circumgalactic medium (CGM) out to twice the virial radius. As central gas densities and pressures are reduced, we find weaker signals from the CGM in mock X-ray and Sunyaev-Zeldovich maps, whose detection - with proposed instruments such as Lynx, and even potentially presently with ALMA - can constrain quasar feedback.

Connecting the Young Pulsars in Milky Way Globular Clusters with White Dwarf Mergers and the M81 Fast Radio Burst

Authors: Kyle Kremer, Jim Fuller, Anthony L. Piro, Scott M. Ransom
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.11933
Pdf link: https://arxiv.org/pdf/2305.11933
Abstract
The detections of four apparently young radio pulsars in the Milky Way globular clusters are difficult to reconcile with standard neutron star formation scenarios associated with massive star evolution. Here we discuss formation of these young pulsars through white dwarf mergers in dynamically-old clusters that have undergone core collapse. Based on observed properties of magnetic white dwarfs, we argue neutron stars formed via white dwarf merger are born with spin periods of roughly $10-100,$ms and magnetic fields of roughly $10^{11}-10^{13},$G. As these neutron stars spin down via magnetic dipole radiation, they naturally reproduce the four observed young pulsars in the Milky Way clusters. Rates inferred from $N$-body cluster simulations as well as the binarity, host cluster properties, and cluster offsets observed for these young pulsars hint further at a white dwarf merger origin. These young pulsars may be descendants of neutron stars capable of powering fast radio bursts analogous to the bursts observed recently in a globular cluster in M81.

LSST Survey Strategy in the Galactic Plane and Magellanic Clouds

Authors: R.A. Street, X. Li, S. Khakpash, E. Bellm, L. Girardi, L. Jones, N.S. Abrams, Y. Tsapras, M.P.G. Hundertmark, E. Bachelet, P. Gandhi, P. Szkody, W.I. Clarkson, R. Szabo, L. Prisinzano, R. Bonito, D.A.H. Buckley, J.P. Marais, R. Di Stefano
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.11988
Pdf link: https://arxiv.org/pdf/2305.11988
Abstract
Galactic science encompasses a wide range of subjects in the study of the Milky Way and Magellanic Clouds, from Young Stellar Objects to X-ray Binaries. Mapping these populations, and exploring transient phenomena within them, are among the primary science goals of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). While early versions of the survey strategy dedicated relatively few visits to the Galactic Plane region, more recent strategies under consideration envision higher cadence within selected regions of high scientific interest. The range of galactic science presents a challenge in evaluating which strategies deliver the highest scientific returns. Here we present metrics designed to evaluate Rubin survey strategy simulations based on the cadence of observations they deliver within regions of interest to different topics in galactic science, using variability categories defined by timescale. We also compare the fractions of exposures obtained in each filter with those recommended for the different science goals. We find that the baseline_v2.x simulations deliver observations of the high-priority regions at sufficiently high cadence to reliably detect variability on timescales >10 d or more. Follow-up observations may be necessary to properly characterize variability, especially transients, on shorter timescales. Combining the regions of interest for all the science cases considered, we identify those areas of the Galactic Plane and Magellanic Clouds of highest priority. We recommend that these refined survey footprints be used in future simulations to explore rolling cadence scenarios, and to optimize the sequence of observations in different bandpasses.

Estimating Ejecta Masses of Stripped Envelope Supernovae Using Late-Time Light Curves

Authors: Annastasia Haynie, Anthony L. Piro
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.12005
Pdf link: https://arxiv.org/pdf/2305.12005
Abstract
Stripped-envelope supernovae (SESNe) are a subclass of core-collapse supernovae that are deficient in hydrogen (SN~~IIb, SN~~Ib) and possibly helium (SN~Ic) in their spectra. Their progenitors are likely stripped of this material through a combination of stellar winds and interactions with a close binary companion, but the exact ejecta mass ranges covered by each subtype and how it relates to the zero-age main-sequence progenitor mass is still unclear. Using a combination of semi-analytic modeling and numerical simulations, we discuss how the properties of SESN progenitors can be constrained through different phases of the bolometric light curve. We find that the light curve rise time is strongly impacted by the strength of radioactive nickel mixing and treatment of helium recombination. These can vary between events and are often not accounted for in simpler modeling approaches, leading to large uncertainties in ejecta masses inferred from the rise. Motivated by this, we focus on the late time slope, which is determined by gamma-ray leakage. We calibrate the relationship between ejecta mass, explosion energy, and gamma-ray escape time $T_0$ using a suite of numerical models. Application of the fitting function we provide to bolometric light curves of SESNe should result in ejecta masses with approximately 20% uncertainty. With large samples of SESNe coming from current and upcoming surveys, our methods can be utilized to better understand the diversity and origin of the progenitor stars.

Unveiling the small-scale jets in the rapidly growing supermassive black hole IZw1

Authors: Xiaolong Yang, Su Yao, Luigi C. Gallo, Jun Yang, Luis C. Ho, Minfeng Gu, Willem A. Baan, Jiri Svoboda, Ran Wang, Xiang Liu, Xiaoyu Hong, Xue-Bing Wu, Wei Zhao
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.12525
Pdf link: https://arxiv.org/pdf/2305.12525
Abstract
Accretion of black holes at near-Eddington or super-Eddington rates is the most powerful episode that drives black hole growth, and it may work in several types of objects. However, the physics of accretion and jet-disc coupling in such a state remains unclear, mainly because the associated jets are not easily detectable due to the extremely weak emission or possibly episodic nature of the jets. Only a few near/super-Eddington systems have demonstrated radio activity, and it remains unclear whether there is a jet and what are their properties, in super-Eddington active galactic nuclei (AGNs) (and ultraluminous X-ray sources). The deficit is mainly due to the complex radio mixing between the origins of jets and others, such as star formation activity, photo-ionized gas, accretion disk wind, and coronal activity. In this work, we conducted high-resolution very long baseline interferometry (VLBI) observations to explore the jets in the highly accreting narrow-line Seyfert I system IZw1. Our observations successfully revealed small-scale jets (with a linear size of $\sim45$ parsec) at both 1.5 and 5 GHz, based on the high radio brightness temperature, radio morphology, and spectral index distribution. Interestingly, the lack of a flat-spectrum radio core and knotty jet structures imply episodic ejections in IZw1, which resemble the ejection process in Galactic X-ray binaries that are in the canonical very high state. The high accretion rates and jet properties in the AGN IZw1 may support the AGN/XRB analogy in the extreme state.

The core starbursts of the galaxy NGC 3628: Radio very long baseline interferometry and X-ray studies

Authors: Xiaolong Yang, Ziwei Ou
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.12526
Pdf link: https://arxiv.org/pdf/2305.12526
Abstract
We present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7$-$7 parsec) radio sources in the central $\sim$250 parsec region of NGC 3628. Based on their morphology, high radio brightness temperatures ($10^5-10^7$ K), and steep radio spectra, none of these seven sources can be associated with active galactic nuclei (AGNs); instead, they can be identified as supernova remnants (SNRs), with three of them appearing consistent with partial shells. Notably, one of them (W2) is likely a nascent radio supernova and appears to be consistent with the star formation rate of NGC 3628 when assuming a canonical initial mass function. The VLBI observation provides the first precise measurement of the diameter of the radio sources in NGC 3628, which allow us to fit a well-constrained radio surface brightness - diameter ($\Sigma-D$) correlation by including the detected SNRs. Furthermore, future VLBI observations can be conducted to measure the expansion velocity of the detected SNRs. In addition to our radio VLBI study, we analyze Chandra and XMM-Newton spectra of NGC 3628. The spectral fitting indicates that the SNR activities could well account for the observed X-ray emissions. Along with the Chandra X-ray image, it further reveals that the X-ray emission is likely maintained by the galactic-scale outflow triggered by SN activities. These results provide strong evidence that SN-triggered activities play a critical role in generating both radio and X-ray emissions in NGC 3628 and further suggest that the galaxy NGC 3628 is in an early stage of starbursts.

High-resolution APEX/LAsMA $^{12}$CO and $^{13}$CO (3-2) observation of the G333 giant molecular cloud complex : I. Evidence for gravitational acceleration in hub-filament systems

Authors: J. W. Zhou, F. Wyrowski, S. Neupane, J. S. Urquhart, N. J. Evans II, E. Vázquez-Semadeni, K. M. Menten, Y. Gong, T. Liu
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.12573
Pdf link: https://arxiv.org/pdf/2305.12573
Abstract
Hub-filament systems are suggested to be the birth cradles of high-mass stars and clusters. We apply the FILFINDER algorithm to the integrated intensity maps of the 13CO (3-2) line to identify filaments in the G333 complex, and extract the velocity and intensity along the filament skeleton from moment maps. Clear velocity and density fluctuations are seen along the filaments, allowing us to fit velocity gradients around the intensity peaks. The velocity gradients fitted to the LAsMA data and ALMA data agree with each other over the scales covered by ALMA observations in the ATOMS survey. Changes of velocity gradient with scale indicate a ''funnel'' structure of the velocity field in PPV space, indicative of a smooth, continuously increasing velocity gradient from large to small scales, and thus consistent with gravitational acceleration. The typical velocity gradient corresponding to a 1 pc scale is ~1.6km/s/pc. Assuming free-fall, we estimate a kinematic mass within 1 pc of ~1190 M$_\odot$, which is consistent with typical masses of clumps in the ATLASGAL survey. We find direct evidence for gravitational acceleration from comparison of the observed accelerations to those predicted by free-fall onto dense hubs. On large scales, we find that the inflow may be driven by the larger scale structure, consistent with hierarchical structure in the molecular cloud and gas inflow from large to small scales. The hub-filament structures at different scales may be organized into a hierarchical system extending up to the largest scales probed, through the coupling of gravitational centers at different scales. We argue that the ''funnel'' structure in PPV space can be an effective probe for the gravitational collapse motions in molecular clouds. The large scale gas inflow is driven by gravity, implying that the molecular clouds in G333 complex may be in the state of global gravitational collapse.

A New Photoionization Model of the Narrow Line Region in Active Galactic Nuclei

Authors: Peixin Zhu, Lisa J. Kewley, Ralph S. Sutherland
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.12670
Pdf link: https://arxiv.org/pdf/2305.12670
Abstract
The photoionization model of narrow-line regions (NLRs) in active galactic nuclei (AGNs) has been investigated for decades. Many published models are restricted to simple linear scaling abundance relations, dust-free assumption, uniform AGN radiation field, and using one specific photoionization code, which restricts them from providing a satisfactory prediction on a broad range of AGN observations. Through a comprehensive investigation, here we present how the choice of abundance scaling relations, dust inclusion, AGN radiation fields, and different photoionization codes CLOUDY and MAPPINGS affect the predictions on the strength of strong UV, optical, and infrared emission lines. We find the dust-depleted radiation pressure-dominated AGN model built with the latest non-linear abundance sets and photoionization code MAPPINGS V are consistent with AGN observations across a broad range of wavelengths. We also assess new potential HII-AGN separation diagrams in the optical and UV wavelengths.

An elusive dark central mass in the globular cluster M4

Authors: Eduardo Vitral, Mattia Libralato, Kyle Kremer, Gary A. Mamon, Andrea Bellini, Luigi R. Bedin, Jay Anderson
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.12702
Pdf link: https://arxiv.org/pdf/2305.12702
Abstract
Recent studies of nearby globular clusters have discovered excess dark mass in their cores, apparently in an extended distribution, and simulations indicate that this mass is composed mostly of white dwarfs (respectively stellar-mass black holes) in clusters that are core-collapsed (respectively with a flatter core). We perform mass-anisotropy modelling of the closest globular cluster, M4, with intermediate slope for the inner stellar density. We use proper-motion data from Gaia EDR3 and from observations by the Hubble Space Telescope. We extract the mass profile employing Bayesian Jeans modelling, and check our fits with realistic mock data. Our analyses return isotropic motions in the cluster core and tangential motions ($\beta\approx -0.4$$\pm$$0.1$) in the outskirts. We also robustly measure a dark central mass of roughly $800\pm300 ,$M$_{\odot}$, but it is not possible to distinguish between a point-like source, such as an intermediate-mass black hole (IMBH), or a dark population of stellar remnants of extent $\approx 0.016,\rm pc \simeq 3300,AU$. However, when removing a high-velocity star from the cluster centre, the same mass excess is found, but more extended ($\sim 0.034, \rm{pc} \approx 7000,\rm AU$). We use Monte Carlo $N$-body models of M4 to interpret the second outcome, and find that our excess mass is not sufficiently extended to be confidently associated with a dark population of remnants. Finally, we discuss the feasibility of these two scenarios (i.e., IMBH vs. remnants), and propose new observations that could help to better grasp the complex dynamics in M4's core.

Halo formation and evolution in SFDM and CDM: new insights from the fluid approach

Authors: Horst Foidl, Tanja Rindler-Daller, Werner Zeilinger
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); Fluid Dynamics (physics.flu-dyn)
Arxiv link: https://arxiv.org/abs/2305.12982
Pdf link: https://arxiv.org/pdf/2305.12982
Abstract
(abridged) We present simulations of halo formation and evolution in scalar field dark matter (SFDM) cosmologies in the Thomas-Fermi regime, aka SFDM-TF", where a strong repulsive 2-particle self-interaction (SI) is included, being a valuable alternative to CDM, with the potential to resolve its cusp-core" problem. In general, SFDM behaves like a quantum fluid. Previous literature has presented two fluid approximations for SFDM-TF, as well as simulations of halo formation. These results confirmed earlier expectations and are generally in mutual agreement, but discrepancies were also reported. Therefore, we perform dedicated 3D cosmological simulations for the SFDM-TF model, applying both fluid approximations, as well as for CDM. Our results are very well in accordance with previous works and extend upon them, in that we can explain the reported discrepancies as a result of different simulation setups. We find some interesting details: The evolution of both SFDM-TF and CDM halos follows a 2-stage process. In the early stage, the density profile in the center becomes close to a $(n=1.5)$-polytropic core, dominated by an "effective" velocity-dispersion pressure $P_{\sigma}$ which is common to both dark matter models. Consecutively, for CDM halos, the core transitions into a central cusp. In SFDM-TF halos, the additional pressure $P_\text{SI}$ due to SI determines the second stage of the evolution, where the central region follows closely a $(n=1)$-polytropic core, embedded in a nearly isothermal envelope, i.e. the outskirts are similar to CDM. We also encounter a new effect, namely a late-time expansion of both polytropic core plus envelope, because the size of the almost isothermal halo envelope is affected by the expansion of the background universe. So, an initial primordial core of $\sim 100$ pc can evolve into a larger core of $\gtrsim 1$ kpc, even without feedback from baryons.

High Sensitivity Observations of the Water Megamasers of NGC 1068: Precise Astrometry and Detailed Kinematics

Authors: Jack F. Gallimore, C. M. Violette Impellizzeri
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13097
Pdf link: https://arxiv.org/pdf/2305.13097
Abstract
We present High Sensitivity Array observation of the water megamasers of NGC 1068. We obtain absolute astrometry with 0.3 mas precision that confirms the association of the disk masers with the nuclear radio continuum source S1. The new observations reveal two new blueshifted groups of disk masers. We also detect the 22 GHz continuum on short interferometric baselines. The position-velocity diagram of the disk masers shows a curve consistent with a nonaxisymmetric distribution of maser spots. The curve is probably the result of spiral arms with a constant pitch angle of roughly 5 degrees. The disk kinematics are consistent with Keplerian rotation and low turbulent speeds. The inferred central mass is 17 million solar masses. On the basis of disk stability arguments, the mass of the molecular disk is roughly 110 thousand solar masses. The disk masers further resolve into filamentary structures suggesting an ordered magnetic field threading the maser disk. The magnetic field strengths must be greater than 1.6 mG to withstand turbulent motions in the partially ionized molecular gas. We note apparent asymmetries in the molecular disk that might be explained by anisotropic heating by a misaligned inner accretion disk. The new observations also detect the fainter jet masers north of the disk masers. The distribution and kinematics of the jet masers are consistent with an expanding ring of molecular gas.

Density biases and temperature relations for DESIRED HII regions

Authors: J. E. Méndez-Delgado, C. Esteban, J. García-Rojas, K. Z. Arellano-Córdova, K. Kreckel, V. Gómez-Llanos, O. V. Egorov, M. Peimbert, M. Orte-García
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13136
Pdf link: https://arxiv.org/pdf/2305.13136
Abstract
We present a first study based on the analysis of the DEep Spectra of Ionized REgions Database (DESIRED). This is a compilation of 190 high signal-to-noise ratio optical spectra of HII regions and other photoionized nebulae, mostly observed with 8-10m telescopes and containing $\sim$29380 emission lines. We find that the electron density --$n_{\rm e}$-- of the objects is underestimated when [SII] $\lambda6731/\lambda6716$ and/or [OII] $\lambda3726/\lambda3729$ are the only density indicators available. This is produced by the non-linear density dependence of the indicators in the presence of density inhomogeneities. The average underestimate is $\sim 300$ cm$^{-3}$ in extragalactic HII regions, introducing systematic overestimates of $T_{\rm e}$([OII]) and $T_{\rm e}$([SII]) compared to $T_{\rm e}$([NII]). The high-sensitivity of [OII] $\lambda\lambda7319+20+30+31/\lambda\lambda3726+29$ and [SII] $\lambda\lambda4069+76/\lambda\lambda6716+31$ to density makes them more suitable for the diagnosis of the presence of high-density clumps. If $T_{\rm e}$([NII]) is adopted, the density underestimate has a small impact in the ionic abundances derived from optical spectra, being limited to up to $\sim$0.1 dex when auroral [SII] and/or [OII] lines are used. However, these density effects are critical for the analysis of infrared fine structure lines, such as those observed by the JWST in local star forming regions, implying strong underestimates of the ionic abundances. We present temperature relations between $T_{\rm e}$([OIII]), $T_{\rm e}$([ArIII]), $T_{\rm e}$([SIII]) and $T_{\rm e}$([NII]) for the extragalactic HII regions. We confirm a non-linear dependence between $T_{\rm e}$([OIII])-$T_{\rm e}$([NII]) due to a more rapid increase of $T_{\rm e}$([OIII]) at lower metallicities.

A panoptic view of the Taurus molecular cloud I. The cloud dynamics revealed by gas emission and 3D dust

Authors: J. D. Soler, C. Zucker, J. E. G. Peek, M. Heyer, P. F. Goldsmith, S. C. O. Glover, S. Molinari, R. S. Klessen, P. Hennebelle, L. Testi, T. Colman, M. Benedettini, D. Elia, C. Mininni, S. Pezzuto, E. Schisano, A. Traficante
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.13180
Pdf link: https://arxiv.org/pdf/2305.13180
Abstract
We present a study of the three-dimensional (3D) distribution of interstellar dust derived from stellar extinction observations toward the Taurus molecular cloud (MC) and its relation with the neutral atomic hydrogen (HI) emission at 21 cm wavelength and the carbon monoxide $^{12}$CO and $^{13}$CO emission in the $J=1\rightarrow0$ transition. We used the histogram of oriented gradients (HOG) method to match the morphology in a 3D reconstruction of the dust density (3D dust) and the distribution of the gas tracers' emission. The result of the HOG analysis is a map of the relationship between the distances and radial velocities. The HOG comparison between the 3D dust and the HI emission indicates a morphological match at the distance of Taurus but an anti-correlation between the dust density and the HI emission, which uncovers a significant amount of cold HI within the Taurus MC. The HOG between the 3D dust and $^{12}$CO reveals a pattern in radial velocities and distances that is consistent with converging motions of the gas in the Taurus MC, with the near side of the cloud moving at higher velocities and the far side moving at lower velocities. This convergence of flows is likely triggered by the large-scale gas compression caused by the interaction of the Local Bubble and the Per-Tau shell, with Taurus lying at the intersection of the two bubble surfaces.

Winking filaments due to cyclic evaporation-condensation

Authors: Yuhao Zhou, Xiaohong Li, Jie Hong, Rony Keppens
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.13237
Pdf link: https://arxiv.org/pdf/2305.13237
Abstract
Observations have shown that some filaments appear and disappear in the H$\alpha$ line wing images periodically. There have been no attempts to model these "winking filaments" thus far. The evaporation--condensation mechanism is widely used to explain the formation of solar filaments. Here, we demonstrate, for the first time, how multi-dimensional evaporation--condensation in an arcade setup invariably causes a stretching of the magnetic topology. We aim to check whether this magnetic stretching during cyclic evaporation--condensation could reproduce a winking filament. We used our open-source code MPI-AMRVAC to carry out 2D magnetohydrodynamic simulations based on a quadrupolar configuration. A periodic localized heating, which modulates the evaporation--condensation process, was imposed before, during, and after the formation of the filament. Synthetic H$\alpha$ and 304 \r{A}, images were produced to compare the results with observations. For the first time, we noticed the winking filament phenomenon in a simulation of the formation of on-disk solar filaments, which was in good agreement with observations. Typically, the period of the winking is different from the period of the impulsive heating. A forced oscillator model explains this difference and fits the results well. A parameter survey is also done to look into details of the magnetic stretching phenomenon. We found that the stronger the heating or the higher the layer where the heating occurs, the more significant the winking effect appears.

Using Giant Pulses to Measure the Impulse Response of the Interstellar Medium

Authors: Nikhil Mahajan, Marten H. van Kerkwijk
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.13274
Pdf link: https://arxiv.org/pdf/2305.13274
Abstract
Giant pulses emitted by PSR B1937+21 are bright, intrinsically impulsive bursts. Thus, the observed signal from a giant pulse is a noisy but direct measurement of the impulse response from the ionized interstellar medium. We use this fact to detect 13,025 giant pulses directly in the baseband data of two observations of PSR B1937+21. Using the giant pulse signals, we model the time-varying impulse response with a sparse approximation method, in which the time dependence at each delay is decomposed in Fourier components, thus constructing a wavefield as a function of delay and differential Doppler shift. We find that the resulting wavefield has the expected parabolic shape, with several diffuse structures within it, suggesting the presence of multiple scattering locations along the line of sight. We also detect an echo at a delay of about 2.4 ms, over 1.5 times the rotation period of the pulsar, which between the two observations moves along the trajectory expected from geometry. The structures in the wavefield are insufficiently sparse to produce a complete model of the system, and hence the model is not predictive across gaps larger than about the scintillation time. Nevertheless, within its range, it reproduces about 75% of the power of the impulse response, a fraction limited mostly by the signal-to-noise ratio of the observations. Furthermore, we show that by deconvolution, using the model impulse response, we can successfully recover the intrinsic pulsar emission from the observed signal.

by olozhika (Xing Yuchen).

2023-05-23

New submissions for Tue, 9 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-09

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 17papers

No Surviving SN Ia Companion In SNR 0509-67.5: Stellar Population Characterization and Comparison To Models

Authors: Joshua V. Shields, Prasiddha Arunachalam, Wolfgang Kerzendorf, John P. Hughes, Sofia Biriouk, Hayden Monk, Johannes Buchner
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.03750
Pdf link: https://arxiv.org/pdf/2305.03750
Abstract
The community agrees that Type Ia supernovae arise from Carbon/Oxygen white dwarfs undergoing thermonuclear runaway. However, the full progenitor system and the process that prompts the white dwarf to explode remain unknown. Most current models suggest that the white dwarf explodes because of interaction with a binary companion which may survive the process and remain within the resulting remnant of the exploded star. Furthermore, both the pre-supernova interaction process and the explosion of the primary are expected to imprint a significant departure from ordinary stellar radii and temperatures onto the secondary, making the star identifiable against the unrelated stellar population. Identification of a surviving companion inside an SN Ia remnant might confirm a specific corresponding SN Ia progenitor channel based on the identity of the companion. We conducted a surviving companion search of the Type Ia remnant SNR 0509-67.5 based in the Large Magellanic Cloud. The well-constrained distance to and foreground extinction of the Large Magellanic Cloud allow for Bayesian inference of stellar parameters with low correlation and uncertainties. We present a deep catalog of fully characterized stars interior to SNR 0509-67.5 with radii, effective temperatures, and metallicities inferred using combined Hubble Space Telescope photometric observations across multiple visits. We then compile a list of surviving companion models appropriate for the age of the remnant (roughly 400 years after the explosion). We compare these predictions with the inferred stellar parameters and conclude that none of the stars are consistent with the predicted signatures of a surviving companion.

Flight of the Bumblebee: the Early Excess Flux of Type Ia Supernova 2023bee revealed by $TESS$, $Swift$ and Young Supernova Experiment Observations

Authors: Qinan Wang, Armin Rest, Georgios Dimitriadis, Ryan Ridden-harper, Matthew R. Siebert, Mark Magee, Charlotte R. Angus, Katie Auchettl, Kyle W. Davis, Ryan J. Foley, Ori D. Fox, Sebastian Gomez, Jacob E. Jencson, David O. Jones, Charles D. Kilpatrick, Justin D. R. Pierel, Anthony L. Piro, Abigail Polin, Collin A. Politsch, César Rojas-bravo, Melissa Shahbandeh, V. Ashley Villar, Yossef Zenati, C. Ashall, Kenneth C. Chambers, David A. Coulter, Thomas De Boer, Nico Dilullo, Christa Gall, Hua Gao, Eric Y. Hsiao, Mark E. Huber, Luca Izzo, Nandita Khetan, Natalie Lebaron, Eugene A. Magnier, Kaisey S. Mandel, Peter Mcgill, Hao-yu Miao, Yen-chen Pan, Catherine P. Stevens, Jonathan J. Swift, Kirsty Taggart, Grace Yang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.03779
Pdf link: https://arxiv.org/pdf/2305.03779
Abstract
We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee in NGC~2708 ($D = 32 \pm 3$ Mpc), finding excess flux in the first days after explosion relative to the expected power-law rise from an expanding fireball. This deviation from typical behavior for SNe Ia is particularly obvious in our 10-minute cadence $TESS$ light curve and $Swift$ UV data. Compared to a few other normal SNe Ia with detected early excess flux, the excess flux in SN 2023bee is redder in the UV and less luminous. We present optical spectra of SN 2023bee, including two spectra during the period where the flux excess is dominant. At this time, the spectra are similar to those of other SNe Ia but with weaker Si II, C II and Ca II absorption lines, perhaps because the excess flux creates a stronger continuum. We compare the data to several theoretical models that have been proposed to explain the early flux excess in SNe Ia. Interaction with either a nearby companion star or close-in circumstellar material is expected to produce a faster evolution than seen in the data. Radioactive material in the outer layers of the ejecta, either from a double detonation explosion or simply an explosion with a $^{56}$Ni clump near the surface, can not fully reproduce the evolution either, likely due to the sensitivity of early UV observable to the treatment of the outer part of ejecta in simulation. We conclude that no current model can adequately explain the full set of observations. We find that a relatively large fraction of nearby, bright SNe Ia with high-cadence observations have some amount of excess flux within a few days of explosion. Considering potential asymmetric emission, the physical cause of this excess flux may be ubiquitous in normal SNe Ia.

Spatially resolved imaging of the inner Fomalhaut disk using JWST/MIRI

Authors: Andras Gaspar, Schuyler Grace Wolff, George H. Rieke, Jarron M. Leisenring, Jane Morrison, Kate Y. L. Su, Kimberly Ward-Duong, Jonathan Aguilar, Marie Ygouf, Charles Beichman, Jorge Llop-Sayson, Geoffrey Bryden
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.03789
Pdf link: https://arxiv.org/pdf/2305.03789
Abstract
Planetary debris disks around other stars are analogous to the Asteroid and Kuiper belts in the Solar System. Their structure reveals the configuration of small bodies and provides hints for the presence of planets. The nearby star Fomalhaut hosts one of the most prominent debris disks, resolved by HST, Spitzer, Herschel, and ALMA. Images of this system at mid-infrared wavelengths using JWST/MIRI not only show the narrow Kuiper-Belt-analog outer ring, but also that (1) what was thought from indirect evidence to be an asteroid-analog structure is instead broad, extending outward into the outer system; (2) there is an intermediate belt, probably shepherded by an unseen planet. The newly discovered belt is demarcated by an inner gap, located at ~ 78 au, and it is misaligned relative to the outer belt. The previously known collisionally generated dust cloud, Fomalhaut b, could have originated from this belt, suggesting increased dynamical stirring and collision rates there. We also discovered a large dust cloud within the outer ring, possible evidence of another dust-creating collision. Taken together with previous observations, Fomalhaut appears to be the site of a complex and possibly dynamically active planetary system.

Revisiting the Dragonfly Galaxy I. High-resolution ALMA and VLA Observations of the Radio Hotspots in a Hyper-luminous Infrared Galaxy at $z=1.92$

Authors: Yuxing Zhong, Akio K. Inoue, Yuma Sugahara, Kana Morokuma-Matsui, Shinya Komugi, Hiroyuki Kaneko, Yoshinobu Fudamoto
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.03979
Pdf link: https://arxiv.org/pdf/2305.03979
Abstract
Radio-loud active galactic nuclei (RLAGNs) are rare among AGN populations. Lacking high-resolution and high-frequency observations, their structure and evolution stages are not well understood at high redshifts. In this work, we report ALMA 237 GHz continuum observation at $0.023''$ resolution and VLA 44 GHz continuum observation at $0.08''$ resolution of the radio continuum emission from a high-redshift radio and hyper-luminous infrared galaxy at $z=1.92$. The new observations confirm the South-East (SE) and North-West (NW) hotspots identified by previous low-resolution VLA observations at 4.7 and 8.2 GHz and identify a radio core undetected in all previous observations. The SE hotspot has a higher flux density than the NW one does by a factor of 6, suggesting that there can be a Doppler boosting effect in the SE one. In this scenario, we estimate the advance speed of the jet head, ranging from $\sim$0.1c -- 0.3c, which yields a mildly relativistic case. The projected linear distance between the two hotspots is $\sim13$ kpc, yielding a linear size ($\leq20$ kpc) of a Compact-Steep-Spectrum (CSS) source. Combined with new \black{high-frequency ($\nu_\text{obs}\geq44$ GHz) and archived low-frequency observations ($\nu_\text{obs}\leq8.2$ GHz)}, we find that injection spectra of both NW and SE hotspots can be fitted with a continuous injection (CI) model. Based on the CI model, the synchrotron ages of NW and SE hotspots have an order of $10^5$ yr, consistent with the order of magnitude $10^3 - 10^5$ yr observed in CSS sources associated with radio AGNs at an early evolution stage. The CI model also favors the scenario in which the double hotspots have experienced a quiescent phase, suggesting that this RLAGN may have transient or intermittent activities.

Core Collapse Supernova Explosions in Active Galactic Nucleus Accretion Disks

Authors: Fu-Lin Li, Yu Liu, Xiao Fan, Mao-Kai Hu, Xuan Yang, Jin-Jun Geng, Xue-Feng Wu
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04010
Pdf link: https://arxiv.org/pdf/2305.04010
Abstract
Astrophysical events that occur in active galactic nucleus (AGN) disks are believed to differ significantly from the ordinary in the interstellar medium. We show that stars located in the outer region of the AGN disk would explode near the original migration starting points instead of being accreted by the central supermassive black hole due to the effect of viscosity. AGN disks provide a dense environment for supernova (SN) explosions, which inevitably involve ejecta-disk interactions. In this paper, we investigate the light curves (LCs) of core-collapse SN exploded in AGN disks. In addition to the fundamental energy source of $^{56} \mathrm{Ni}$--$^{56} \mathrm{Co}$--$^{56} \mathrm{Fe}$ decay reaction powering the SN LCs, the forward-reverse shock produced during interactions may contribute significantly to the observed flux. If the stellar winds manage to create a cavity surrounded by a shell near the star before the SN explosion, the ejecta-winds-disk configurations are expected. We present various SN LCs from different types of progenitors and find that the SN LCs are dominated by the radiation of ejecta-disk interaction-induced shocks. The resulting SNe in the AGN disk is a promising transient source for UV and optical band detection by the Neil Gehrels Swift Observatory (Swift), the Ultraviolet Explorer (UVEX) and wide field survey telescopes such as Ultraviolet Transient Astronomy Satellite (ULTRASAT), Wide Field Survey Telescope (WFST) and Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory. These detections could aid in the investigation of AGN discs and the associated high-energy transient occurrences.

Infall and Outflow Towards High-mass Starless Clump Candidates

Authors: T. G. S. Pillai (1), J. S. Urquhart (2), S. Leurini (3), Q. Zhang (4), A. Traficante (5), D. Colombo (6), K. Wang (7), L. Gomez (8), F. Wyrowski (6) ((1) Boston University, (2) University of Kent, (3) INAF - Osservatorio Astronomico di Cagliari, (4) CfA, Harvard & Smithsonian, (5) IAPS - INAF, (6) MPIfR, (7) Kavli Institute, China, (8) Joint Alma Observatory, Chile)
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04256
Pdf link: https://arxiv.org/pdf/2305.04256
Abstract
The evolutionary sequence for high-mass star formation starts with massive starless clumps that go on to form protostellar, young stellar objects and then compact HII regions. While there are many examples of the three later stages, the very early stages have proved to be elusive. We follow-up a sample of 110 mid-infrared dark clumps selected from the ATLASGAL catalogue with the IRAM telescope in an effort to identify a robust sample of massive starless clumps. We have used the HCO+ (1-0) and HNC (1-0) transitions to identify clumps associated with infall motion and the SiO (2-1) transition to identity outflow candidates. We have found blue asymmetric line profile in 65% of the sample, and have measured the infall velocities and mass infall rates (0.6-$36 \times 10^{-3}$ Msun/yr) for 33 of these clumps. We find a trend for the mass infall rate decreasing with an increase of bolometric luminosity to clump mass i.e. star formation within the clumps evolves. Using the SiO 2-1 line, we have identified good outflow candidates. Combining the infall and outflow tracers reveals that 67% of quiescent clumps are already undergoing gravitational collapse or are associated with star formation; these clumps provide us with our best opportunity to determined the initial conditions and study the earliest stages of massive star formation. Finally, we provide an overview of a systematic high-resolution ALMA study of quiescent clumps selected that allows us to develop a detailed understanding of earliest stages and their subsequent evolution.

ATLASGAL: 3-mm class I methanol masers in high-mass star formation regions

Authors: W. Yang, Y. Gong, K. M. Menten, J. S. Urquhart, C. Henkel, F. Wyrowski, T. Csengeri, S. P. Ellingsen, A. R. Bemis, J. Jang
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04264
Pdf link: https://arxiv.org/pdf/2305.04264
Abstract
We analyzed the 3-mm wavelength spectral line survey of 408 ATLASGAL clumps observed with the IRAM 30m-telescope, focusing on the class I methanol masers with frequencies near 84, 95 and 104.3 GHz. We detect narrow, maser-like features towards 54, 100 and 4 sources in the maser lines near 84, 95 and 104.3 GHz, respectively. Among them, fifty 84 GHz masers, twenty nine 95 GHz masers and four rare 104.3 GHz masers are new discoveries. The new detections increase the number of known 104.3 GHz masers from 5 to 9. The 95 GHz class I methanol maser is generally stronger than the 84 GHz maser counterpart. We find 9 sources showing class I methanol masers but no SiO emission, indicating that class I methanol masers might be the only signpost of protostellar outflow activity in extremely embedded objects at the earliest evolutionary stage. Class I methanol masers that are associated with sources that show SiO line wings are more numerous and stronger than those without such wings. The total integrated intensity of class I methanol masers is well correlated with the integrated intensity and velocity coverage of the SiO (2--1) emission. The properties of class I methanol masers are positively correlated with the bolometric luminosity, clump mass, peak H$_2$ column density of their associated clumps but uncorrelated with the luminosity-to-mass ratio, dust temperature, and mean H$_2$ volume density. We suggest that the properties of class I masers are related to shocks traced by SiO. Based on our observations, we conclude that class I methanol masers at 84 and 95 GHz can trace a similar evolutionary stage as H$_2$O maser, and appear prior to 6.7 and 12.2 GHz methanol and OH masers. Despite their small number, the 104.3 GHz class I masers appear to trace a short and more evolved stage compared to the other class I masers. [abridged]

Unveiling the initial conditions of open star cluster formation

Authors: C. J. Hao, Y. Xu, L. G. Hou, Z. H. Lin, Y. J. Li
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04415
Pdf link: https://arxiv.org/pdf/2305.04415
Abstract
Open clusters (OCs) are infrequent survivors of embedded clusters gestated in molecular clouds. Up to now, little is known about the initial conditions for the formation of OCs. Here, we studied this issue using high-precision astrometric parameters provided by Gaia data release 3. The statistics show that the peculiar motion velocities of OCs vary little from infancy to old age, providing a remarkable opportunity to use OCs to trace their progenitors. Adopting a dynamical method, we derived the masses of the progenitor clumps where OCs were born, which have statistical characteristics comparable to previously known results for clumps observed in the Galaxy. Moreover, the masses of the progenitor clumps of OCs indicate they should be capable of gestating massive O-type stars. In fact, after inspecting the observed OCs and O-type stars, we found that there are many O-type stars in OCs. The destructive stellar feedback from O-type stars may disintegrate the vast majority of embedded clusters, and only those sufficiently dense ones can survive as OCs.

Stability of interlinked neutron vortex and proton flux-tube arrays in a neutron star -- III. Proton feedback

Authors: K. H. Thong, A. Melatos, L. V. Drummond
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2305.04482
Pdf link: https://arxiv.org/pdf/2305.04482
Abstract
The coupled, time-dependent Gross-Pitaevskii and Ginzburg-Landau equations are solved simultaneously in three dimensions to investigate the equilibrium state and far-from-equilibrium, spin-down dynamics of an interpenetrating neutron superfluid and proton type-II superconductor, as an idealized description of the outer core of a neutron star. The simulations generalize previous calculations without the time-dependent Ginzburg-Landau equation, where proton feedback is absent. If the angle $\theta$ between the rotation and magnetic axes does not equal zero, the equilibrium state consists of geometrically complicated neutron vortex and proton flux-tube tangles, as the topological defects pin to one another locally but align with different axes globally. During spin-down, new types of motion are observed. For $\theta = 0$, entire vortices pair rectilinearly with flux tubes and move together while pinned. For $\theta \neq 0$, vortex segments pair with segments from one or more flux tubes, and the paired segments move together while pinned. The degree to which proton feedback impedes the deceleration of the crust is evaluated as a function of $\theta$ and the pinning strength, $\eta$. Key geometric properties of vortex-flux-tube tangles, such as filament length, mean curvature, and polarity are analysed. It is found that proton feedback smooths the deceleration of the crust, reduces the rotational glitch sizes, and stabilizes the vortex tangle dynamics. The dimensionless control parameters in the simulations are mutually ordered to match what is expected in a real neutron star, but their central values and dynamics ranges differ from reality by many orders of magnitude due to computational limitations.

Near-Infrared Spectroscopy of Dense Ejecta Knots in the Outer Eastern Area of the Cassiopeia A Supernova Remnant

Authors: Bon-Chul Koo, Yong-Hyun Lee, Jae-Joon Lee, Sung-Chul Yoon
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04484
Pdf link: https://arxiv.org/pdf/2305.04484
Abstract
The Cassiopeia A supernova remnant has a complex structure, manifesting the multidimensional nature of core-collapse supernova explosions. To further understand this, we carried out near-infrared multi-object spectroscopy on the ejecta knots located in the "northeastern (NE) jet" and the "Fe K plume" regions, which are two distinct features in the outer eastern area of the remnant. Our study reveals that the knots exhibit varying ratios of [S II] 1.03 $\mu$m, [P II] 1.189 $\mu$m, and [Fe II] 1.257 $\mu$m lines depending on their locations within the remnant, suggesting regional differences in elemental composition. Notably, the knots in the NE jet are mostly 'S-rich' with weak or no [P II] lines, implying that they originated below the explosive Ne burning layer, consistent with the results of previous studies. We detected no ejecta knots exhibiting only [Fe II] lines in the NE jet area that are expected in the jet-driven SN explosion model. Instead, we discovered a dozen 'Fe-rich' knots in the Fe K plume area. We propose that they are dense knots produced by a complete Si burning with $\alpha$-rich freezeout in the innermost region of the progenitor and ejected with the diffuse X-ray emitting Fe ejecta but decoupled after crossing the reverse shock. In addition to these metal-rich ejecta knots, several knots emitting only He I 1.083 $\mu$m lines were detected, and their origin remains unclear. We also detected three extended H emission features of circumstellar or interstellar origin in this area and discuss its association with the supernova remnant.

Radiation pressure acting on the neutral He atoms in the Heliosphere

Authors: Izabela Kowalska-Leszczynska, Marzena A. Kubiak, Maciej Bzowski
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04510
Pdf link: https://arxiv.org/pdf/2305.04510
Abstract
The Interstellar Neutral Helium (ISN He) is an important source of information on the physical state of the Local Interstellar Medium. Radiation pressure acting on the neutral helium atoms in the heliosphere has always been neglected, its effect has been considered insignificant compared to gravitational force. The most advanced numerical models of ISN He take into account more and more subtle effects, therefore it is important to check if the effect of radiation pressure is still negligible. In this paper, we use the most up-to-date version of the Warsaw Test Particle Model (WTPM) to calculate the expected helium distribution in the heliosphere, and simulate the flux of ISN He observed by the Interstellar Boundary Explorer (IBEX) and in the future by the Interstellar Mapping and Acceleration Probe (IMAP). We compare results calculated with and without radiation pressure during low and high solar activity. The results show that in the analysis of IBEX-Lo observations the radiation pressure acting on typical helium causes flux differences at a level of 1-4% and is comparable to the observational errors. For the more sensitive IMAP-Lo instrument, there are some regions in the considered observations configurations where radiation pressure causes potentially statistically significant changes in the calculated fluxes. The effect can be up to 9% for the indirect beam and is likely to be higher than the estimated errors. Therefore, we claim that in the future analysis of the IMAP-Lo observations radiation pressure acting on ISN He should be considered.

Precise Masses, Ages of ~1.0 million RGB and RC stars observed by the LAMOST

Authors: Chun Wang, Yang Huang, Yutao Zhou, Huawei Zhang
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04528
Pdf link: https://arxiv.org/pdf/2305.04528
Abstract
We construct a catalogue of stellar masses and ages for 696,680 red giant branch (RGB) stars, 180,436 primary red clump (RC) stars, and 120,907 secondary RC stars selected from the LAMOST,DR8. The RGBs, primary RCs, and secondary RCs are identified with the large frequency spacing ($\Delta \nu$) and period spacing ($\Delta P$), estimated from the LAMOST spectra with spectral SNRs $> 10$ by the neural network method supervised with the seismologic information from LAMOST-Kepler sample stars. The purity and completeness of both RGB and RC samples are better than 95% and 90%, respectively. The mass and age of RGBs and RCs are determined again with the neural network method by taking the LAMOST-Kepler giant stars as the training set. The typical uncertainties of stellar mass and age are, respectively, 10% and 30% for the RGB stellar sample. For RCs, the typical uncertainties of stellar mass and age are 9% and 24%, respectively. The RGB and RC stellar samples cover a large volume of the Milky Way (5 $< R < 20$,kpc and $|Z| <$,5,kpc), which are valuable data sets for various Galactic studies.

High energy gamma-ray emission powered by a young protostar: the case of S255 NIRS 3

Authors: Emma de Oña Wilhelmi, Rubén López-Coto, Yang Su
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.04571
Pdf link: https://arxiv.org/pdf/2305.04571
Abstract
Evidence of efficient acceleration of cosmic rays in massive young stellar objects has been recently reported. Among these massive protostars, S255 NIRS 3 for which extreme flaring events associated with radio jets have been detected, is one of the best objects to test this hypothesis. We search for gamma-ray emission associated with this object in Fermi-LAT data and inspect the gas content in different molecular lines using the MWISP survey. A GeV source dubbed 4FGL J0613.1+1749c lies on top of the MYSO region, where two filamentary ~10 pc CO structures extend along the same direction of the sub-parsec radio jets. We investigate the spectrum, morphology, and light curve of the gamma-ray source and compare it with the theoretical emission expected from hadronic and leptonic populations accelerated in the radio jets. We argue that the gamma-ray source could be powered by particles accelerated in the S255 NIRS 3 jets, radiating via Bremsstrahlung or proton-proton interaction, and with a synchrotron component shinning in radio from primary or secondary electrons in the case of a leptonic or hadronic population.

First evidence of multi-iron sub-populations in the Bulge Fossil Fragment candidate Liller 1

Authors: Chiara Crociati, Elena Valenti, Francesco R. Ferraro, Cristina Pallanca, Barbara Lanzoni, Mario Cadelano, Cristiano Fanelli, Livia Origlia, Emanuele Dalessandro, Alessio Mucciarelli, R. Michael Rich
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04595
Pdf link: https://arxiv.org/pdf/2305.04595
Abstract
In the context of a project aimed at characterizing the properties of the so-called Bulge Fossil Fragments (the fossil remnants of the bulge formation epoch), here we present the first determination of the metallicity distribution of Liller 1. For a sample of 64 individual member stars we used ESO- MUSE spectra to measure the equivalent width of the CaII triplet and then derive the iron abundance. To test the validity of the adopted calibration in the metal-rich regime, the procedure was first applied to three reference bulge globular clusters (NGC 6569, NGC 6440, and NGC 6528). In all the three cases, we found single-component iron distributions, with abundance values fully in agreement with those reported in the literature. The application of the same methodology to Liller 1 yielded, instead, a clear bimodal iron distribution, with a sub-solar component at $\text{[Fe/H]}= -0.48,$dex ($\sigma = 0.22$) and a super-solar component at $\text{[Fe/H]}= +0.26,$dex ($\sigma = 0.17$). The latter is found to be significantly more centrally concentrated than the metal-poor population, as expected in a self-enrichment scenario and in agreement with what found in another bulge system, Terzan 5. The obtained metallicity distribution is astonishingly similar to that predicted by the reconstructed star formation history of Liller 1, which is characterized by three main bursts and a low, but constant, activity of star formation over the entire lifetime. These findings provide further support to the possibility that, similar to Terzan 5, also Liller 1 is a Bulge Fossil Fragment.

${\rm H_2CN}$/${\rm H_2NC}$ abundance ratio: a new potential temperature tracer for the interstellar medium

Authors: David San Andrés (1 and 2), Laura Colzi (1), Víctor M. Rivilla (1), Juan García de la Concepción (3 and 4), Mattia Melosso (5), Jesús Martín-Pintado (1), Izaskun Jiménez-Serra (1), Shaoshan Zeng (6), Sergio Martín (7 and 8), Miguel A. Requena-Torres (9 and 10) ((1) Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Madrid, Spain, (2) Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Madrid, Spain, (3) Departamento de Química Orgánica e Inorgánica, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain, (4) IACYS-Unidad de Química Verde y Desarrollo Sostenible, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain, (5) Scuola Superiore Meridionale, Naples, Italy, (6) Star and Planet Formation Laboratory, Cluster for Pioneering Research, RIKEN, Hirosawa, Wako, Saitama, Japan, (7) European Southern Observatory, Vitacura, Santiago, Chile, (8) Joint ALMA Observatory, Vitacura, Santiago, Chile, (9) University of Maryland, College Park, USA, (10) Department of Physics, Astronomy and Geosciences, Towson University, USA)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04611
Pdf link: https://arxiv.org/pdf/2305.04611
Abstract
The ${\rm H_2NC}$ radical is the high-energy metastable isomer of ${\rm H_2CN}$ radical, which has been recently detected for the first time in the interstellar medium towards a handful of cold galactic sources, besides a warm galaxy in front of the PKS 1830-211 quasar. These detections have shown that the ${\rm H_2CN}$/${\rm H_2NC}$ isomeric ratio, likewise the HCN/HNC ratio, might increase with the kinetic temperature ($T_{\rm kin}$), but the shortage of them in warm sources still prevents us to confirm this hypothesis and shed light about their chemistry. In this work, we present the first detection of ${\rm H_2CN}$ and ${\rm H_2NC}$ towards a warm galactic source, the G+0.693-0.027 molecular cloud (with $T_{\rm kin} > 70 , {\rm K}$), using IRAM 30m observations. We have detected multiple hyperfine components of the $N_{K_\text{a}K_\text{c}} = 1_{01} - 0_{00}$ and $2_{02} - 1_{01}$ transitions. We derived molecular abundances with respect to ${\rm H_2}$ of (6.8$\pm$1.3)$\times 10^{-11}$ for ${\rm H_2CN}$ and of (3.1$\pm$0.7)$\times 10^{-11}$ for ${\rm H_2NC}$, and a ${\rm H_2CN}$/${\rm H_2NC}$ abundance ratio of 2.2$\pm$0.5. These detections confirm that the ${\rm H_2CN}$/${\rm H_2NC}$ ratio is $\gtrsim$2 for sources with $T_{\rm kin} > 70 , {\rm K}$, larger than the $\sim$1 ratios previously found in colder cores ($T_{\rm kin}\sim10 , {\rm K}$). This isomeric ratio dependence with temperature cannot be fully explained with the currently proposed gas-phase formation and destruction pathways. Grain surface reactions, including the ${\rm H_2NC} \rightarrow {\rm H_2CN}$ isomerization, deserve consideration to explain the higher isomeric ratios and ${\rm H_2CN}$ abundances observed in warm sources, where the molecules can be desorbed into the gas phase through thermal and/or shock-induced mechanisms.

Evolution of radioactive elements in the LMC: predictions for future gamma-ray surveys

Authors: Arianna Vasini, Francesca Matteucci, Emanuele Spitoni, Thomas Siegert
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.04753
Pdf link: https://arxiv.org/pdf/2305.04753
Abstract
Short-lived radionuclides, such as 26Al and 60Fe, are tracers of star formation. Therefore, their abundances can unravel the recent star formation history of the host galaxy. In view of future gamma-ray surveys, we predict the masses and fluxes of these two elements in the Large Magellanic Cloud (LMC) using new chemical evolution models. Our best model reproduces the abundance patterns of alpha/Fe ratios, the gas mass, the average metallicity, the present time supernova and nova rates observed in LMC. We show three main results: i) the best model for the LMC suggests a star formation rate very mild at the beginning with a recent burst, and a Salpeter-like initial mass function. ii) The predicted mass of 26Al is 0.33 M_Sun, 2/3 produced by massive stars and 1/3 by novae. iii) The predicted mass of 60Fe is 0.44 M_Sun, entirely produced by massive stars. This result suggests a larger fraction of 60Fe, at variance with the Milky Way. The explanation for this lies in the adopted initial mass function, that for the LMC contains more massive stars than for the Milky Way. These predictions can be useful for the COSI-SMEX mission planned for launch in 2027. The expected gamma-ray line fluxes for the 1.809 MeV line of 26Al and the 1.173 and 1.332 MeV lines of 60Fe are in the range of (0.2-2.7)x10^-6 ph cm^-2 s^-1 and (0.7-2.8)x10^-7 ph cm^-2 s^-1, respectively. This new instrument could have the sensitivity to detect the upper end of the predicted 1.8 MeV flux within its nominal two-year mission.

An unusually low-density super-Earth transiting the bright early-type M-dwarf GJ 1018 (TOI-244)

Authors: A. Castro-González, O.D.S. Demangeon, J. Lillo-Box, C. Lovis, B. Lavie, V. Adibekyan, L. Acuña, M. Deleuil, A. Aguichine, M. R. Zapatero Osorio, H. M. Tabernero, J. Davoult, Y. Alibert, N. Santos, S. G. Sousa, A. Antoniadis-Karnavas, F. Borsa, J. N. Winn, C. Allende Prieto, P. Figueira, J. M. Jenkins, A. Sozzetti, M. Damasso, A. M. Silva, N. Astudillo-Defru, S. C. C. Barros, X. Bonfils, S. Cristiani, P. Di Marcantonio, J. I. González Hernández, G. Lo Curto, C. J. A. P. Martins, N. J. Nunes, E. Palle, F. Pepe, S. Seager, A. Suárez Mascareño
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.04922
Pdf link: https://arxiv.org/pdf/2305.04922
Abstract
Small planets located at the lower mode of the bimodal radius distribution are generally assumed to be composed of iron and silicates in a proportion similar to that of the Earth. However, recent discoveries are revealing a new group of low-density planets that are inconsistent with that description. We intend to confirm and characterize the TESS planet candidate TOI-244.01, which orbits the bright ($K$ = 7.97 mag), nearby ($d$ = 22 pc), and early-type (M2.5 V) M-dwarf star GJ 1018 with an orbital period of 7.4 days. We used Markov Chain Monte Carlo methods to model 57 precise radial velocity measurements acquired by the ESPRESSO spectrograph together with TESS photometry and complementary HARPS data. We find TOI-244 b to be a super-Earth with a radius of $R_{\rm p}$ = 1.52 $\pm$ 0.12 $\rm R_{\oplus}$ and a mass of $M_{\rm p}$ = 2.68 $\pm$ 0.30 $\rm M_{\oplus}$. These values correspond to a density of $\rho$ = 4.2 $\pm$ 1.1 $\rm g \cdot cm^{-3}$, which is below what would be expected for an Earth-like composition. We find that atmospheric loss processes may have been efficient to remove a potential primordial hydrogen envelope, but high mean molecular weight volatiles such as water could have been retained. Our internal structure modeling suggests that TOI-244 b has a $479^{+128}{-96}$ km thick hydrosphere over a 1.17 $\pm$ 0.09 $\rm R{\oplus}$ solid structure composed of a Fe-rich core and a silicate-dominated mantle compatible with that of the Earth. On a population level, we find two tentative trends in the density-metallicity and density-insolation parameter space for the low-density super-Earths, which may hint at their composition. With a 8$%$ precision in radius and 12$%$ precision in mass, TOI-244 b is among the most precisely characterized super-Earths, which, together with the likely presence of an extended hydrosphere, makes it a key target for atmospheric observations.

New submissions for Mon, 29 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 8papers

Mapping the multiphase structure of H I in the Low-Latitude Intermediate-Velocity Arch 1

Authors: Luka Vujeva, Antoine Marchal, Peter G. Martin, Mukesh Taank
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.16414
Pdf link: https://arxiv.org/pdf/2305.16414
Abstract
We have analyzed the thermal and turbulent properties of the Low-Latitude Intermediate-Velocity Arch 1 (LLIV1). This was accomplished using archival H I emission and absorption data from two 21,cm line surveys: GHIGLS at $9.^\prime$4 resolution and DHIGLS at $1^\prime$ resolution. The spectral decomposition code $\tt{ROHSA}$ was used to model the column density of different thermal phases and also to analyze an absorption measurement against the radio source 4C~+66.09. From the latter we found spin temperature $T_{\mathrm{s}} \sim 75$K, cold gas mass fraction $f\sim0.5$, and turbulent sonic Mach number $M_t\sim3.4$. Similar to the absorption line modeling against 4C~+66.09, our best emission line decomposition model has no unstable gas across the whole field of view, suggesting that the thermal condensation and phase transition are not on-going but rather have reached an equilibrium state. The cold phase of LLIV1 appears as a collection of elongated filaments that forms a closed structure within the field decomposed. These substructures follow the orientation of the overall large scale cloud, along the diagonal of the GHIGLS field from north-west to south-east (in Galactic coordinates). The angular power spectrum of the cold phase is slightly shallower than that of the warm phase, quantifying that the cold phases have relatively more structure on small scales. Our spatially resolved map of the cold gas mass fraction in LLIV1 from DHIGLS reveals significant variations spanning the possible range of $f$, with mean and standard deviation 0.33 and 0.19, respectively.

New Measurement of Muon Neutrino Disappearance from the IceCube Experiment

Authors: Shiqi Yu (for the IceCube Collaboration)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
Arxiv link: https://arxiv.org/abs/2305.16514
Pdf link: https://arxiv.org/pdf/2305.16514
Abstract
The IceCube Neutrino Observatory is a Cherenkov detector located at the South Pole. Its main component consists of an in-ice array of optical modules instrumenting one cubic kilometer of deep Glacial ice. The DeepCore sub-detector is a denser in-fill array with a lower energy threshold, allowing us to study atmospheric neutrinos oscillations with energy below 100 GeV arriving through the Earth. We present preliminary results of an atmospheric muon neutrino disappearance analysis using data from 2012 to 2021 and employing convolutional neural networks (CNNs) for precise and fast event reconstructions.

Improving Multi-Dimensional Data Formats, Access, and Assimilation Tools for the Twenty-First Century

Authors: Daniel B. Seaton, Amir Caspi, Roberto Casini, Cooper Downs, Sarah E. Gibson, Holly Gilbert, Lindsay Glesener, Silvina E. Guidoni, J. Marcus Hughes, David McKenzie, Joseph Plowman, Katharine K. Reeves, Pascal Saint-Hilaire, Albert Y. Shih, Matthew J. West
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); Data Analysis, Statistics and Probability (physics.data-an); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2305.16535
Pdf link: https://arxiv.org/pdf/2305.16535
Abstract
Heliophysics image data largely relies on a forty-year-old ecosystem built on the venerable Flexible Image Transport System (FITS) data standard. While many in situ measurements use newer standards, they are difficult to integrate with multiple data streams required to develop global understanding. Additionally, most data users still engage with data in much the same way as they did decades ago. However, contemporary missions and models require much more complex support for 3D multi-parameter data, robust data assimilation strategies, and integration of multiple individual data streams required to derive complete physical characterizations of the Sun and Heliospheric plasma environment. In this white paper we highlight some of the 21$^\mathsf{st}$ century challenges for data frameworks in heliophysics, consider an illustrative case study, and make recommendations for important steps the field can take to modernize its data products and data usage models. Our specific recommendations include: (1) Investing in data assimilation capability to drive advanced data-constrained models, (2) Investing in new strategies for integrating data across multiple instruments to realize measurements that cannot be produced from single observations, (3) Rethinking old data use paradigms to improve user access, develop deep understanding, and decrease barrier to entry for new datasets, and (4) Investing in research on data formats better suited for multi-dimensional data and cloud-based computing.

Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud

Authors: Authors: The Cherenkov Telescope Array Consortium
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.16707
Pdf link: https://arxiv.org/pdf/2305.16707
Abstract
A deep survey of the Large Magellanic Cloud at ~0.1-100TeV photon energies with the Cherenkov Telescope Array is planned. We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters, mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N157B, N132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3-2.4 pending a flux increase by a factor >3-4 over ~2015-2035. Large-scale interstellar emission remains mostly out of reach of the survey if its >10GeV spectrum has a soft photon index ~2.7, but degree-scale 0.1-10TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1-10% of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within <100pc. Finally, the survey could probe the canonical velocity-averaged cross section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles.

Aluminium-26 from massive binary stars III. Binary stars up to core-collapse and their impact on the early Solar System

Authors: Hannah E. Brinkman (1, 2, 3), C. L. Doherty (4), M. Pignatari (1,5,6), O. R. Pols (7), M. Lugaro (1,4,8) ((1) Konkoly Observatory, Research Centre for Astronomy and Earth Sciences (CSFK), Eötvös Loránd Research Network (ELKH), MTA Center of Excellence, Budapest, Hungary (2) Graduate School of Physics, University of Szeged, Hungary (3) Institute of Astronomy, KU Leuven, Leuven, Belgium (4) School of Physics and Astronomy, Monash University, Australia (5) E. A. Milne Centre for Astrophysics, Department of Physics and Mathematics, University of Hull, United Kingdom (6) NuGrid Collaboration, (7) {Department of Astrophysics/IMAPP, Radboud University, Nijmegen, The Netherlands, (8) ELTE Eötvös Loránd University, Institute of Physics, Budapest, Hungary)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.16787
Pdf link: https://arxiv.org/pdf/2305.16787
Abstract
Many of the short-lived radioactive nuclei that were present in the early Solar System can be produced in massive stars. In the first paper in this series (Brinkman et al. 2019), we focused on the production of $^{26}$Al in massive binaries. In our second paper (Brinkman et al. 2021), we considered rotating single stars, two more short-lived radioactive nuclei, $^{36}$Cl and $^{41}$Ca, and the comparison to the early Solar System data. In this work, we update our previous conclusions by further considering the impact of binary interactions. We used the MESA stellar evolution code with an extended nuclear network to compute massive (10-80 M$ {\odot} $), binary stars at various initial periods and solar metallicity (Z=0.014), up to the onset of core collapse. The early Solar System abundances of $^{26}$Al and $^{41}$Ca can be matched self-consistently by models with initial masses $\geq$25 M${\odot}$, while models with initial primary masses $\geq$35 M${\odot}$ can also match $^{36}$Cl. Almost none of the models provide positive net yields for $^{19}$F, while for $^{22}$Ne the net yields are positive from 30 M${\odot}$ and higher. This leads to an increase by a factor of approximately 4 in the amount of $^{22}$Ne produced by a stellar population of binary stars, relative to single stars. Also, besides the impact on the stellar yields, our 10 M$_{\odot}$ primary star undergoing Case A mass-transfer ends its life as a white dwarf instead of as a core-collapse supernova. This demonstrates that binary interactions can also strongly impact the evolution of stars close to the supernova boundary.

QCD, Gravitational Waves, and Pulsars

Authors: Partha Bagchi, Oindrila Ganguly, Biswanath Layek, Anjishnu Sarkar, Ajit M. Srivastava
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.16850
Pdf link: https://arxiv.org/pdf/2305.16850
Abstract
Investigations of the phase diagram of quantum chromodynamics (QCD) have revealed that exotic new phases, the so called {\it color superconducting phases}, may arise at very high baryon densities. It is speculated that these exotic phases may arise in the cores of neutron stars. Focus on neutrons stars has tremendously intensified in recent years with the direct detection of gravitational waves (GW) by LIGO/Virgo from BNS merger events which has allowed the possibility of directly probing the properties of the interior of a neutron star. A remarkable phenomenon manifested by rapidly rotating neutron stars is in their {\it avatar} as {\it Pulsars}. The accuracy of pulsar timing can reach the level of one part in 10$^{15}$, comparable to that of atomic clocks. This suggests that even a tiny deformation of the pulsar can leave its imprints on the pulses by inducing tiny perturbations in the entire moment of inertia (MI) tensor affecting the pulse timings, as well as the pulse profile (from wobbling induced by off-diagonal MI components). This may allow a new probe of various phase transitions occurring inside a pulsar core through induced density fluctuations affecting the MI tensor. Such perturbations also naturally induce a rapidly changing quadrupole moment of the star, thereby providing a new source of gravitational wave emission. Another remarkable possibility arises when we consider the effect of an external GW on neutron star. With the possibility of detecting any minute changes in its configuration through pulse observations, the neutron star has the potential of performing as a Weber detector of gravitational wave. This brief review will focus on these specific aspects of a pulsar. Specifically, the focus will be on the type of physics which can be probed by utilizing the effect of changes in the MI tensor of the pulsar on pulse properties.

Awesome SOSS: Atmospheric Characterisation of WASP-96 b using the JWST Early Release Observations

Authors: Jake Taylor, Michael Radica, Luis Welbanks, Ryan J. MacDonald, Jasmina Blecic, Maria Zamyatina, Alexander Roth, Jacob L. Bean, Vivien Parmentier, Louis-Philippe Coulombe, Adina D. Feinstein, Néstor Espinoza, Björn Benneke, David Lafrenière, René Doyon, Eva-Maria Ahrer
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.16887
Pdf link: https://arxiv.org/pdf/2305.16887
Abstract
The newly operational JWST offers the potential to study the atmospheres of distant worlds with precision that has not been achieved before. One of the first exoplanets observed by JWST in the summer of 2022 was WASP-96 b, a hot-Saturn orbiting a G8 star. As part of the Early Release Observations program, one transit of WASP-96 b was observed with NIRISS/SOSS to capture its transmission spectrum from 0.6-2.85 microns. In this work, we utilise four retrieval frameworks to report precise and robust measurements of WASP-96 b's atmospheric composition. We constrain the logarithmic volume mixing ratios of multiple chemical species in its atmosphere, including: H$2$O = $-3.59 ^{+ 0.35 }{- 0.35 }$, CO$2$ = $-4.38 ^{+ 0.47 }{- 0.57 }$ and K = $-8.04 ^{+ 1.22 }_{- 1.71 }$. Notably, our results offer a first abundance constraint on potassium in WASP-96 b's atmosphere, and important inferences on carbon-bearing species such as CO$_2$ and CO. Our short wavelength NIRISS/SOSS data are best explained by the presence of an enhanced Rayleigh scattering slope, despite previous inferences of a clear atmosphere - although we find no evidence for a grey cloud deck. Finally, we explore the data resolution required to appropriately interpret observations using NIRISS/SOSS. We find that our inferences are robust against different binning schemes. That is, from low $R = 125$ to the native resolution of the instrument, the bulk atmospheric properties of the planet are consistent. Our systematic analysis of these exquisite observations demonstrates the power of NIRISS/SOSS to detect and constrain multiple molecular and atomic species in the atmospheres of hot giant planets.

Awesome SOSS: Transmission Spectroscopy of WASP-96b with NIRISS/SOSS

Authors: Michael Radica, Luis Welbanks, Néstor Espinoza, Jake Taylor, Louis-Philippe Coulombe, Adina D. Feinstein, Jayesh Goyal, Nicholas Scarsdale, Loic Albert, Priyanka Baghel, Jacob L. Bean, Jasmina Blecic, David Lafrenière, Ryan J. MacDonald, Maria Zamyatina, Romain Allart, Étienne Artigau, Natasha E. Batalha, Neil James Cook, Nicolas B. Cowan, Lisa Dang, René Doyon, Marylou Fournier-Tondreau, Doug Johnstone, Michael R. Line, Sarah E. Moran, Sagnick Mukherjee, Stefan Pelletier, Pierre-Alexis Roy, Geert Jan Talens, Joseph Filippazzo, Klaus Pontoppidan, Kevin Volk
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.17001
Pdf link: https://arxiv.org/pdf/2305.17001
Abstract
The future is now - after its long-awaited launch in December 2021, JWST began science operations in July 2022 and is already revolutionizing exoplanet astronomy. The Early Release Observations (ERO) program was designed to provide the first images and spectra from JWST, covering a multitude of science cases and using multiple modes of each on-board instrument. Here, we present transmission spectroscopy observations of the hot-Saturn WASP-96b with the Single Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph, observed as part of the ERO program. As the SOSS mode presents some unique data reduction challenges, we provide an in-depth walk-through of the major steps necessary for the reduction of SOSS data: including background subtraction, correction of 1/f noise, and treatment of the trace order overlap. We furthermore offer potential routes to correct for field star contamination, which can occur due to the SOSS mode's slitless nature. By comparing our extracted transmission spectrum with grids of atmosphere models, we find an atmosphere metallicity between 1x and 5x solar, and a solar carbon-to-oxygen ratio. Moreover, our models indicate that no grey cloud deck is required to fit WASP-96b's transmission spectrum, but find evidence for a slope shortward of 0.9$\mu$m, which could either be caused by enhanced Rayleigh scattering or the red wing of a pressure-broadened Na feature. Our work demonstrates the unique capabilities of the SOSS mode for exoplanet transmission spectroscopy and presents a step-by-step reduction guide for this new and exciting instrument.

by olozhika (Xing Yuchen).

2023-05-29

New submissions for Tue, 30 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

How the modeling of mixing and nuclear energy production impacts the extent of convective cores

Authors: Anthony Noll, Sébastien Deheuvels
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.17176
Pdf link: https://arxiv.org/pdf/2305.17176
Abstract
Convective cores are the hydrogen reservoirs of main sequence stars that are more massive than around 1.2 solar masses. The characteristics of the cores have a strong impact on the evolution and structure of the star. However, such results rely on stellar evolution codes in which simplistic assumptions are often made on the physics in the core. Indeed, the mixing is commonly considered to be instantaneous and the most basic nuclear networks assume beryllium at its equilibrium abundance. Those assumptions lead to significant differences in the central composition of the elements for which the timescale to reach nuclear equilibrium is lower than the convective timescale. In this work, we show that those discrepancies impact the nuclear energy production and therefore the size of convective cores in models computed with overshoot. We find that cores computed with instantaneous mixing are up to 30% bigger than those computed with diffusive mixing. Similar differences are found when using basic nuclear networks. Additionally, we observe an extension of the duration of the main sequence due to those core size differences. We then investigate the impact of those structural differences on the seismic modeling of solar-like oscillators. Modeling two stars observed by Kepler, we find that the overshoot parameter of the best models computed with a basic nuclear network is significantly lower compared to models computed with a full nuclear network. This work is a necessary step for a better modeling of convective cores which is key to determine accurate ages in the framework of future space missions such as Plato.

A 3D Numerical Study of Anisotropies in Supernova Remnants

Authors: Soham Mandal, Paul C. Duffell, Abigail Polin, Dan Milisavljevic
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Fluid Dynamics (physics.flu-dyn)
Arxiv link: https://arxiv.org/abs/2305.17324
Pdf link: https://arxiv.org/pdf/2305.17324
Abstract
We develop a suite of 3D hydrodynamic models of supernova remnants (SNRs) expanding against the circumstellar medium (CSM). We study the Rayleigh-Taylor Instability (RTI) forming at the expansion interface by calculating an angular power spectrum for each of these models. The power spectra of young SNRs is seen to exhibit a dominant angular mode, which is a diagnostic of their ejecta density profile as found by previous studies. The steep scaling of power at smaller modes and the time evolution of the spectra is indicative of absence of a turbulent cascade. Instead, as the time evolution of the spectra suggests, they may be governed by an angular mode dependent net growth rate. We also study the impact of anisotropies in the ejecta as well as in the CSM on the power spectra of velocity and density. We confirm that perturbations in the density field (whether imposed on the ejecta or the CSM) do not influence the anisotropy of the remnant significantly unless they have a very large amplitude and form large-scale coherent structures. In any case, these clumps can only affect structures on large angular scales. The power spectra on small angular scales is completely independent of the initial clumpiness and only governed by the growth and saturation of the Rayleigh-Taylor instability.

Two-element interferometer for millimeter-wave solar flare observations

Authors: Yonglin Yu, Shuo Xu, Lei Zhang, Ziqian Shang, Chenglong Qiao, Shuqi Li, Zhao Wu, Yanrui Su, Hongqiang Song, Yao Chen, Fabao Yan
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.17424
Pdf link: https://arxiv.org/pdf/2305.17424
Abstract
In this paper, we present the design and implementation of a two-element interferometer working in the millimeter wave band (39.5 GHz - 40 GHz) for observing solar radio emissions through nulling interference. The system is composed of two 50 cm aperture Cassegrain antennas mounted on a common equatorial mount, with a separation of 230 wavelengths. The cross-correlation of the received signals effectively cancels the quiet solar component of the large flux density (~3000 sfu) that reduces the detection limit due to atmospheric fluctuations. The system performance is obtained as follows: the noise factor of the AFE in the observation band is less than 2.1 dB, system sensitivity is approximately 12.4 K (~34 sfu) with an integration time constant of 0.1 ms (default), the frequency resolution is 153 kHz, and the dynamic range is larger than 30 dB. Through actual testing, the nulling interferometer observes a quiet sun with a low level of output fluctuations (of up to 50 sfu) and has a significantly lower radiation flux variability (of up to 190 sfu) than an equivalent single-antenna system, even under thick cloud cover. As a result, this new design can effectively improve observation sensitivity by reducing the impact of atmospheric and system fluctuations during observation.

Synthetic Light Curves and Spectra from a Self-Consistent 2D Simulation of an Ultra-strippped Supernova

Authors: Thomas Maunder (1), Bernhard Müller (1), Fionntan Callan (2), Stuart Sim (2), Alexander Heger (2), ((1) Monash University, (2) Queen's University Belfast)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.17441
Pdf link: https://arxiv.org/pdf/2305.17441
Abstract
Spectroscopy is an important tool for providing insights into the structure of core-collapse supernova explosions. We use the Monte Carlo radiative transfer code ARTIS to compute synthetic spectra and light curves based on a two-dimensional explosion model of an ultra-stripped supernova. These calculations are designed both to identify observable fingerprints of ultra-stripped supernovae and as a proof-of-principle for using synthetic spectroscopy to constrain the nature of stripped-envelope supernovae more broadly. We predict very characteristic spectral and photometric features for our ultra-stripped explosion model, but find that these do not match observed ultra-stripped supernova candidates like SN 2005ek. With a peak bolometric luminosity of $6.8\times10^{41},\mathrm{erg},\mathrm{s}^{-1}$, a peak magnitude of $-15.9,\mathrm{mag}$ in R-band, and $\Delta m_{15,\mathrm{R}}=3.50$, the model is even fainter and evolves even faster than SN 2005ek as the closest possible analogue in photometric properties. The predicted spectra are extremely unusual. The most prominent features are Mg II lines at 2,800 Angstrom and 4,500 Angstrom and the infrared Ca triplet at late times. The Mg lines are sensitive to the multi-dimensional structure of the model and are viewing-angle dependent. They disappear due to line blanketing by Fe group elements in a spherically averaged model with additional microscopic mixing. In future studies, multi-D radiative transfer calculations need to be applied to a broader range of models to elucidate the nature of observed Type Ib/c supernovae.

The membership of stars, density profile and mass segregation in open clusters using a new machine learning-based method

Authors: Mohammad Noormohammadi, Mehdi Khakian Ghomi, Hossein Haghi
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.17728
Pdf link: https://arxiv.org/pdf/2305.17728
Abstract
A combination of two unsupervised machine learning algorithms, DBSCAN and GMM are used to find members with a high probability of twelve open clusters, M38, NGC2099, Coma Ber, NGC752, M67, NGC2243, Alessi01, Bochum04, M34, M35, M41, and M48, based on Gaia DR3. These clusters have different ages, distances, and numbers of members which makes a suitable cover of these parameters situation to analyze this method. We have identified 752, 1725, 116, 269, 1422, 936, 43, 38, 743, 1114, 783, and 452, probable and possible members with a higher probability than 0.8 for M38, NGC2099, Coma Ber, NGC752, M67, NGC2243, Alessi01, Bochum04, M34, M35, M41, and M48, respectively. Moreover, we obtained the tidal radius, core radius, and clear evidence of mass segregation in ten clusters. From an examination of the high-quality color-magnitude data of the cluster, we obtained one white dwarf for each of NGC752, Coma Ber and M67. In the young open cluster M38, we found all members inside the tidal radius however in the older clusters we found some members outside of the tidal radius, indicating that the young open clusters had not enough time to form clear tidal tails. It is seen that mass segregation occurs at a higher rate in older clusters than the younger ones.

Molecular Clouds in the Galactic Plane from $l$ = [59.75$^\circ$, 74.75$^\circ$] and $b$ = [$-$5.25$^\circ$, +5.25$^\circ$]

Authors: Chunxue Li, Hongchi Wang, Yuehui Ma, Lianghao Lin, Yang Su, Chong Li, Yan Sun, Xin Zhou, Ji Yang
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.18043
Pdf link: https://arxiv.org/pdf/2305.18043
Abstract
In this paper we present the distribution of molecular gas in the Milky Way Galactic plane from $l$ = [59.75, 74.75]$^{\circ}$ and $b$ = [${-}$5.25, +5.25]$^{\circ}$, using the MWISP $^{12}$CO/$^{13}$CO/$\rm {C}^{18}{O}$ emission line data. The molecular gas in this region can be mainly attributed to the Local spur, Local arm, Perseus arm, and Outer arm. Statistics of the physical properties of the molecular gas in each arm, such as excitation temperature, optical depth, and column density, are presented. Using the DBSCAN algorithm, we identified 15 extremely distant molecular clouds with kinematic distances of 14.72$-$17.77 kpc and masses of 363$-$520 M$_{\odot}$, which we find could be part of the Outer Scutum-Centaurus (OSC) arm identified by \cite{2011ApJ...734L..24D} and \cite{2015ApJ...798L..27S}. It is also possible that, 12 of these 15 extremely distant molecular clouds constitute an independent structure between the Outer and the OSC arms or a spur. There exist two Gaussian components in the vertical distribution of the molecular gas in the Perseus spiral arm. These two Gaussian components correspond to two giant filaments parallel to the Galactic plane. We find an upward warping of the molecular gas in the Outer spiral arm with a displacement of around 270 pc with respect to the Galactic mid-plane.

Nitrogen fractionation in ammonia and its insights on nitrogen chemistry

Authors: Elena Redaelli, Luca Bizzocchi, Paola Caselli, Jaime E. Pineda
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.18289
Pdf link: https://arxiv.org/pdf/2305.18289
Abstract
Context. Observations of $\rm ^{14}N/^{15}N$ in the interstellar medium are becoming more frequent thanks to the increased telescope capabilities. However, interpreting these data is still puzzling. In particular, measurements of $\rm ^{14}N/^{15}N$ in diazenylium revealed high levels of anti-fractionation in cold cores. Aims. Furuya & Aikawa (2018), using astrophysical simulations coupled with a gas-grain chemical code, concluded that the $^{15}$N-depletion in prestellar cores could be inherited from the initial stages, when $\rm ^{14}N^{15}N$ is selectively photodissociated and 15N atoms deplete onto the dust grain, forming ammonia ices. We aim to test this hypothesis. Methods. We targeted three sources (the prestellar core L1544, the protostellar envelope IRAS4A, and the shocked region L1157-B1) with distinct degrees of desorption or sputtering of the ammonia ices. We observed the NH3 isotopologues with the GBT, and we inferred the $\rm ^{14}N/^{15}N$ via a spectral fitting of the observed inversion transitions. Results. $^{15}$NH3(1,1) is detected in L1544 and IRAS4A, whilst only upper limits are deduced in L1157-B1. The NH3 isotopic ratio is significantly lower towards the protostar than at the centre of L1544, where it is consistent with the elemental value. We also present the first spatially resolved map of NH3 nitrogen isotopic ratio towards L1544. Conclusions. Our results are in agreement with the hypothesis that ammonia ices are enriched in $^{15}$N, leading to a decrease of the $\rm ^{14}N/^{15}N$ ratio when the ices are sublimated into the gas phase for instance due to the temperature rise in protostellar envelopes. The ammonia $\rm ^{14}N/^{15}N$ value at the centre of L1544 is a factor of 2 lower than that of N2H+, suggesting that the dominant formation pathway is hydrogenation of N atoms on dust grains, followed by non-thermal desorption.

by olozhika (Xing Yuchen).

2023-05-30

New submissions for Thu, 18 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

GlobULeS-V. UVIT/AstroSat studies of stellar populations in NGC 362: Detection of Blue Lurkers in a Globular Cluster

Authors: Arvind K. Dattatrey, R. K. S. Yadav, Gourav Kumawat, Sharmila Rani, Gaurav Singh, Annapurni Subramaniam, Ravi S. Singh
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.09723
Pdf link: https://arxiv.org/pdf/2305.09723
Abstract
We report the discovery of four blue lurkers with low and extremely low-mass white dwarf (ELM WDs) companions in the Galactic globular cluster NGC 362 using AstroSat Ultra Violet Imaging Telescope (UVIT). We analyzed the multi-wavelength spectral energy distribution (SED) of FUV-bright MS stars using data from the UVIT, UVOT, GAIA EDR3, and 2.2m ESO/MPI telescopes. Two each of low-mass WDs and ELM WDs are found as companions for the four blue lurkers by the fitting of two-component SED models. The effective temperatures, radii, luminosities, and masses of two low-mass WDs are (35000, 23000) K, (0.04, 0.05) Rsun , (1.45, 0.22) Lsun , and (0.2, 0.2) Msun, while the two ELM WDs are (14750, 14750) K, (0.09, 0.10) Rsun, (0.34, 0.40) Lsun, and (0.18, 0.18) Msun. The position of blue lurkers within the cluster shows that they originated via the Case A/B mass-transfer mechanism in a low-density environment. This is the first detection of blue lurkers with low-mass WDs and ELM WDs as companions in a globular cluster. The companion cooling age is less than 4 Myr, which suggests that they were just recently formed. These binary systems might have originated due to the cluster recent core collapse.

The Diffuse Ionized Gas of the Large Magellanic Cloud

Authors: B. M. Smart, L. M. Haffner, K. A. Barger, D. A. Ciampa, A. S. Hill, D. Krishnarao, G. J. Madsen
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.09829
Pdf link: https://arxiv.org/pdf/2305.09829
Abstract
The Large Magellanic Cloud (LMC) has an extensive H${\alpha}$ emission halo that traces an extended, warm ionized component of its interstellar medium. Using the Wisconsin H${\alpha}$ Mapper (WHAM) telescope, we present the first kinematic \ha\ survey of an extensive region around the LMC, from $l,b = (264\deg .5,,-45\deg .5)$ to $(295\deg .5,,-19\deg .5)$, covering $+150\leq v_{lsr} \leq +390~ km s^{-1}$. We find that ionized hydrogen exists throughout the galaxy and extends several degrees beyond detected neutral hydrogen emission $(\log{\left(N_{\rm H_{~I}/\rm cm^{-2}}\right)\approx18.3})$ as traced by 21-cm in current surveys. Using the column density structure of the neutral gas and stellar line-of-sight depths as a guide, we estimate the upper limit mass of the ionized component of the LMC to be roughly $M_\mathrm{ionized}\approx (0.6-1.8)\times 10^{9},\mathrm{M}{sun}$, which is comparable to the total neutral atomic gas mass in the same region ($M\mathrm{neutral}\approx0.75-0.85\times10^{9},\mathrm{M}{sun}$). Considering only the atomic phases, we find $M\mathrm{ionized}/M_\mathrm{ionized+neutral}$, to be 46%--68% throughout the LMC and its extended halo. Additionally, we find an ionized gas cloud that extends off of the LMC at $l,b \approx (285\deg, -28\deg)$ into a region previously identified as the Leading Arm complex. This gas is moving at a similar line-of-sight velocity as the LMC and has $M_\mathrm{ionized}/M_\mathrm{ionized+neutral} =$ 13%--51%. This study, combined with previous studies of the SMC and extended structures of the Magellanic Clouds, continues to suggest that warm, ionized gas is as massive and dynamically-important as the neutral gas in the Magellanic System.$

Magnetic Fields and Fragmentation of Filaments in the Hub of California-X

Authors: Eun Jung Chung, Chang Won Lee, Woojin Kwon, Mario Tafalla, Shinyoung Kim, Archana Soam, Jungyeon Cho
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.09949
Pdf link: https://arxiv.org/pdf/2305.09949
Abstract
We present 850 $\mu$m polarization and $\rm C^{18}O (3-2)$ molecular line observations toward the X-shaped nebula in the California molecular cloud using the JCMT SCUBA-2/POL-2 and HARP instruments. The 850 $\mu$m emission shows that the observed region includes two elongated filamentary structures (Fil1 and Fil2) having chains of regularly spaced cores. We measured the mass per unit length of the filament and found that Fil1 and Fil2 are thermally super- and subcritical, respectively, but both are subcritical if nonthermal turbulence is considered. The mean projected spacings ($\Delta\bar S$) of cores in Fil1 and Fil2 are 0.13 and 0.16 pc, respectively. $\Delta\bar S$ are smaller than $4\times$filament width expected in the classical cylinder fragmentation model. The large-scale magnetic field orientations shown by Planck are perpendicular to the long axes of Fil1 and Fil2, while those in the filaments obtained from the high-resolution polarization data of JCMT are disturbed, but those in Fil1 tend to have longitudinal orientations. Using the modified Davis-Chandrasekhar-Fermi (DCF) method, we estimated the magnetic field strengths ($B_{\rm pos}$) of filaments which are 110$\pm$80 and 90$\pm$60 $\mu$G. We calculated the gravitational, kinematic, and magnetic energies of the filaments, and found that the fraction of magnetic energy is larger than 60 % in both filaments. We propose that a dominant magnetic energy may lead the filament to be fragmented into aligned cores as suggested by Tang et al., and a shorter core spacing can be due to a projection effect via the inclined geometry of filaments or due to a non-negligible, longitudinal magnetic fields in case of Fil1.

Testing 2D temperature models in Bayesian retrievals of atmospheric properties from hot Jupiter phase curves

Authors: Jingxuan Yang, Patrick G.J. Irwin, Joanna K. Barstow
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Arxiv link: https://arxiv.org/abs/2305.10249
Pdf link: https://arxiv.org/pdf/2305.10249
Abstract
Spectroscopic phase curves of transiting hot Jupiters are spectral measurements at multiple orbital phases, giving a set of disc-averaged spectra that probe multiple hemispheres. By fitting model phase curves to observations, we can constrain the atmospheric properties of hot Jupiters such as molecular abundance, aerosol distribution and thermal structure, which offer insights into their dynamics, chemistry, and formation. In this work, we propose a novel 2D temperature scheme consisting of a dayside and a nightside to retrieve information from near-infrared phase curves, and apply the scheme to phase curves of WASP-43b observed by HST/WFC3 and Spitzer/IRAC. In our scheme, temperature is constant on isobars on the nightside and varies with cos$^n$(longitude/$\epsilon$) on isobars on the dayside, where $n$ and $\epsilon$ are free parameters. We fit all orbital phases simultaneously using the radiative transfer code NEMESISPY coupled to a Bayesian inference code. We first validate the performance of our retrieval scheme with synthetic phase curves generated from a GCM, and find our 2D scheme can accurately retrieve the latitudinally-averaged thermal structure and constrain the abundance of H$_2$O and CH$_4$. We then apply our 2D scheme to the observed phase curves of WASP-43b and find: (1) the dayside temperature-pressure profiles do not vary strongly with longitude and are non-inverted; (2) the retrieved nightside temperatures are extremely low, suggesting significant nightside cloud coverage; (3) the H$_2$O volume mixing ratio is constrained to $5.6\times10^{-5}$--$4.0\times10^{-4}$, and we retrieve an upper bound for CH$_4$ at $\sim$10$^{-6}$.

Model of Cosmic Ray Propagation in the Milky Way at the Knee

Authors: G. Giacinti, D. Semikoz
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.10251
Pdf link: https://arxiv.org/pdf/2305.10251
Abstract
We present a new model of anisotropic cosmic ray propagation in the Milky Way, where cosmic rays are injected at discrete transient sources in the disc and propagated in the Galactic magnetic field. In the framework of our model, we show that the cosmic ray spectrum is time-dependent and space-dependent around the energy of the knee. It has a major contribution of one or a few nearby recent sources at any given location in the Galaxy, in particular at the position of the Solar system. We find that the distribution of $\sim$ PeV cosmic rays in our Galaxy is significantly clumpy and inhomogeneous, and therefore substantially different from the smoother distribution of GeV cosmic rays. Our findings have important implications for the calculation and future interpretation of the diffuse Galactic gamma-ray and neutrino fluxes at very high energies.

Aspherical ULDM Collapse: Variation in the Core-Halo Mass Relation

Authors: Emily Kendall, Mateja Gosenca, Richard Easther
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.10340
Pdf link: https://arxiv.org/pdf/2305.10340
Abstract
Ultralight dark matter (ULDM) is an interesting alternative to the cold dark matter (CDM) paradigm. Due to the extremely low mass of the constituent particle ($\sim 10^{-22}$ eV), ULDM can exhibit quantum effects up to kiloparsec scales. In particular, runaway collapse in the centres of ULDM halos is prevented by quantum pressure, providing a possible resolution to the 'core-cusp problem' of CDM. However, the the detailed relationship between the ULDM core mass and that of the overall halo is poorly understood. We simulate the collapse of both spherical and aspherical isolated ULDM overdensities using AxioNyx, finding that the central cores of collapsed halos undergo sustained oscillatory behaviour which affects both their peak density and overall morphology. The variability in core morphology increases with the asphericity of the initial overdensity and remnants of initial asphericity persist long after collapse. Furthermore, the peak central densities are higher in spherical configurations. Consequently, astrophysically realistic halos may exhibit substantial departures from theoretical core-halo profiles and we would expect a significant variance of the properties of halos with the same mass.

Field-level Lyman-alpha forest modelling in redshift space via augmented non-local Fluctuating Gunn-Peterson Approximation

Authors: Francesco Sinigaglia, Francisco-Shu Kitaura, Kentaro Nagamine, Yuri Oku, Andrés Balaguera-Antolínez
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.10428
Pdf link: https://arxiv.org/pdf/2305.10428
Abstract
We present an improved analytical model to predict the Lyman-alpha forest at the field level in redshift space from the dark matter field, expanding upon the widely-used Fluctuating Gunn-Peterson approximation (FGPA). In particular, we introduce the dependence on the cosmic web environment (knots, filaments, sheets, voids) in the model, thereby effectively accounting for non-local bias. Furthermore, we include a detailed treatment of velocity bias in the redshift space distortions modelling, allowing the velocity bias to be cosmic-web dependent. We find evidence for a significant difference of the same model parameters in different environments, suggesting that for the investigated setup the simple standard FGPA is not able to adequately predict the Lyman-alpha forest in the different cosmic web regimes. We reproduce the summary statistics of the reference cosmological hydrodynamic simulation we use for comparison, yielding accurate mean transmitted flux, probability distribution function, 3D power spectrum, and bispectrum. In particular, we achieve maximum deviation and average deviations accuracy in the Lyman-alpha forest 3D power spectrum of $\sim 3%$ and $\sim 0.1%$ up to $k\sim 0.4 , h , {\rm Mpc}^{-1}$, $\sim 5%$ and $\sim 1.8%$ up to $k \sim 1.4 , h , {\rm Mpc}^{-1}$. Our new model outperforms previous analytical efforts to predict the Lyman-alpha forest at the field level in all the probed summary statistics, and has the potential to become instrumental in the generation of fast accurate mocks for covariance matrices estimation in the context of current and forthcoming Lyman-alpha forest surveys.

by olozhika (Xing Yuchen).

2023-05-18

New submissions for Wed, 17 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

Astrophysical parameters of M dwarfs with exoplanets

Authors: Carlos Cifuentes
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.08893
Pdf link: https://arxiv.org/pdf/2305.08893
Abstract
M dwarfs are the most abundant stars in the Universe and are hosts of a rich diversity of planetary companions. In many cases, planets orbiting M dwarfs can be described in remarkable detail. What makes the difference is how deeply we can characterise the host star. This includes to properly model their atmospheres, their abundance of metals, and their activity processes. If they are well described individually, these numerous stars have the potential for providing statistically robust conclusions when combined into larger samples. Carmencita is the input catalogue of nearby M dwarfs for the CARMENES project, which aims to search for potentially habitable Earth-sized planets orbiting them. It contains more than two thousand M dwarfs that are scrutinized by the consortium members from multiple angles. This thesis contributes to the description of each one of these M dwarfs, including astrometry, photometry, activity, kinematics, and multiplicity, but also to the study of the sample as a whole. The empirical observations presented in this study provide an important benchmark for testing and improving theoretical predictions. By taking a careful, individualized approach to the study of M dwarfs, we not only contribute to the study of the Universe's physical processes, but we also pave the way for future discoveries of the potential for life beyond our own planet. Overall, the findings of this study underscore the importance of continued research into the most numerous stars and their planetary systems. We expect that the wealth of data gathered in this thesis will serve as a valuable resource for astronomers and researchers in related fields, and that it will inspire further investigations and new insights into the processes that shape the Universe.

Neutron star kicks and implications for their rotation at birth

Authors: Giacomo Fragione, Abraham Loeb
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.08920
Pdf link: https://arxiv.org/pdf/2305.08920
Abstract
Neutron stars are born out of core-collapse supernovae, and they are imparted natal kicks at birth as a consequence of asymmetric ejection of matter and possibly neutrinos. Unless the force resulting from the kicks is exerted exactly at their center, it will also cause the neutron star to rotate. In this paper, we discuss the possibility that neutron stars may receive off-center natal kicks at birth, which imprint a natal rotation. In this scenario, the observed pulsar spin and transverse velocity in the Galaxy are expected to correlate. We develop a model of the natal rotation imparted to neutron stars and constrain it by the observed population of pulsars in our Galaxy. At $90%$ confidence, we find that the location of the off-center kick is $R_{\rm kick}=1.12^{+4.79}_{-0.97}$,km. Our result is robust when considering pulsars with different observed periods, transverse velocities, and ages. Our constraint can be used as a guide for core-collapse simulations of massive stars.

On a discontinuity at the base of the transition layer located between the Keplerian accretion disk and the compact object

Authors: Lev Titarchuk, Ilia Kalashnikov
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.08930
Pdf link: https://arxiv.org/pdf/2305.08930
Abstract
We study the geometry of the transition layer (TL) between the classical Keplerian accretion disk (the TL outer boundary) and the compact object at the TL inner boundary. Our goal is to demonstrate using the hydrodynamical formalism that the TL is created along with a shock due to a discontinuity and to an adjustment of the Keplerian disk motion to a central object. We apply hydrodynamical equations to describe a plasma motion near a central object in the TL. We point out that before matter accretes to a central object the TL cloud is formed between an adjustment radius and the TL inner boundary which is probably a site where the emergent Compton spectrum comes from. Using a generalization of the Randkine-Hugoniot relation and a solution of the azimutal force balance equation we have reproduced the geometric characteristics of TL.

Modelling supernova nebular lines in 3D with $\texttt{ExTraSS}$

Authors: Bart van Baal, Anders Jerkstrand, Annop Wongwathanarat, Thomas H. Janka
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.08933
Pdf link: https://arxiv.org/pdf/2305.08933
Abstract
We present $\texttt{ExTraSS}$ (EXplosive TRAnsient Spectral Simulator), a newly developed code aimed at generating 3D spectra for supernovae in the nebular phase by using modern multi-dimensional explosion models as input. It is well established that supernovae are asymmetric by nature, and that the morphology is encoded in the line profiles during the nebular phase, months after the explosion. In this work, we use $\texttt{ExTraSS}$ to study one such simulation of a $3.3,M_\odot$ He-core explosion ($M_\text{ejecta}=1.3,M_\odot$, $E_\text{kin}=1.05\times10^{51},$erg) modelled with the $\texttt{Prometheus-HotB}$ code and evolved to the homologous phase. Our code calculates the energy deposition from the radioactive decay of $^{56}$Ni $\rightarrow$ $^{56}$Co $\rightarrow$ $^{56}$Fe and uses this to determine the Non-Local-Thermodynamic-Equilibrium temperature, excitation and ionization structure across the nebula. From the physical condition solutions we generate the emissivities to construct spectra depending on viewing angles. Our results show large variations in the line profiles with viewing angles, as diagnosed by the first three moments of the line profiles; shifts, widths, and skewness. We compare line profiles from different elements, and study the morphology of line-of-sight slices that determine the flux at each part of a line profile. We find that excitation conditions can sometimes make the momentum vector of the ejecta emitting in the excited states significantly different from that of the bulk of the ejecta of the respective element, thus giving blueshifted lines for bulk receding material, and vice versa. We compare the 3.3 $M_\odot$ He-core model to observations of the Type Ib supernova SN 2007Y.

New Near-Infrared Period-Luminosity-Metallicity Relations for Galactic RR Lyrae Stars Based on Gaia EDR3 Parallaxes

Authors: Bartłomiej Zgirski, Grzegorz Pietrzyński, Marek Górski, Wolfgang Gieren, Piotr Wielgórski, Paulina Karczmarek, Gergely Hajdu, Megan Lewis, Rolf Chini, Dariusz Graczyk, Mikołaj Kałuszyński, Weronika Narloch, Bogumił Pilecki, Gonzalo Rojas García, Ksenia Suchomska, Mónica Taormina
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.09414
Pdf link: https://arxiv.org/pdf/2305.09414
Abstract
We present new period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars based on a sample of 28 pulsators located at distances up to $1.5$ kpc from the Sun. Near-infrared photometry was obtained at the Cerro Armazones Observatory and parallaxes were taken from the Gaia Early Data Release 3. Relations were determined for the 2MASS $JHK_s$ bands and the $W_{JK}$ Wesenheit index. We compare our results with other calibrations available in the literature and obtain very good agreement with the photometry of RR Lyraes from the Large Magellanic Cloud anchored using the distance to the Cloud, which based on detached eclipsing binaries. We find that the dependence of absolute magnitudes on metallicity of $0.070\pm 0.042$ mag/dex ($J-$ band) to $0.087 \pm 0.031$ mag/dex ($W_{JK}$ index) for the population of fundamental pulsators (RRab) that is in agreement with previously published phenomenological works. We perform a refined determination of distance to the LMC based on our new calibration and photometry from Szewczyk et al. (2008). We study the dependence of the fitted parameters of fiducial relations and the LMC distance on the systematic parallax offset.

Constraining the cosmic-ray pressure in the inner Virgo Cluster using H.E.S.S. observations of M 87

Authors: H.E.S.S. Collaboration: F. Aharonian, F. Ait Benkhali, C. Arcaro, J. Aschersleben, M. Backes, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, K. Bernlöhr, B. Bi, M. Böttcher, C. Boisson, J. Bolmont, J. Borowska, F. Bradascio, M. Breuhaus, R. Brose, F. Brun, B. Bruno, T. Bulik, C. Burger-Scheidlin, T. Bylund, S. Caroff, S. Casanova, R. Cecil, J. Celic, M. Cerruti, T. Chand, S. Chandra, A. Chen, J. Chibueze, O. Chibueze, G. Cotter, J. Damascene Mbarubucyeye, A. Djannati-Ataï, K. Egberts, J.-P. Ernenwein, G. Fichet de Clairfontaine, M. Filipovic, G. Fontaine, M. Füßling, S. Funk, S. Gabici, S. Ghafourizadeh, G. Giavitto, D. Glawion, J.F. Glicenstein, P. Goswami, G. Grolleron, M.-H. Grondin, L. Haerer, M. Haupt, G. Hermann, J.A. Hinton, T. L. Holch, D. Horns, et al. (105 additional authors not shown)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.09607
Pdf link: https://arxiv.org/pdf/2305.09607
Abstract
The origin of the gamma-ray emission from M87 is currently a matter of debate. This work aims to localize the VHE (100 GeV-100 TeV) gamma-ray emission from M87 and probe a potential extended hadronic emission component in the inner Virgo Cluster. The search for a steady and extended gamma-ray signal around M87 can constrain the cosmic-ray energy density and the pressure exerted by the cosmic rays onto the intra-cluster medium, and allow us to investigate the role of the cosmic rays in the active galactic nucleus feedback as a heating mechanism in the Virgo Cluster. H.E.S.S. telescopes are sensitive to VHE gamma rays and have been utilized to observe M87 since 2004. We utilized a Bayesian block analysis to identify M87 emission states with H.E.S.S. observations from 2004 until 2021, dividing them into low, intermediate, and high states. Because of the causality argument, an extended ($\gtrsim$kpc) signal is allowed only in steady emission states. Hence, we fitted the morphology of the 120h low state data and found no significant gamma-ray extension. Therefore, we derived for the low state an upper limit of 58"(corresponding to $\approx$4.6kpc) in the extension of a single-component morphological model described by a rotationally symmetric 2D Gaussian model at 99.7% confidence level. Our results exclude the radio lobes ($\approx$30 kpc) as the principal component of the VHE gamma-ray emission from the low state of M87. The gamma-ray emission is compatible with a single emission region at the radio core of M87. These results, with the help of two multiple-component models, constrain the maximum cosmic-ray to thermal pressure ratio $X_{{CR,max.}}$$\lesssim$$0.32$ and the total energy in cosmic-ray protons (CRp) to $U_{CR}$$\lesssim$5$\times10^{58}$ erg in the inner 20kpc of the Virgo Cluster for an assumed CRp power-law distribution in momentum with spectral index $\alpha_{p}$=2.1.

On the feasibility of structure inversions for gravity-mode pulsators

Authors: Vincent Vanlaer, Conny Aerts, Earl P. Bellinger, Jørgen Christensen-Dalsgaard
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.09624
Pdf link: https://arxiv.org/pdf/2305.09624
Abstract
Gravity-mode asteroseismology has significantly improved our understanding of mixing in intermediate mass stars. However, theoretical pulsation periods of stellar models remain in tension with observations, and it is often unclear how the models of these stars should be further improved. Inversions provide a path forward by directly probing the internal structure of these stars from their pulsation periods, quantifying which parts of the model are in need of improvement. This method has been used for solar-like pulsators, but has not yet been applied to main-sequence gravity-mode pulsators. Our aim is to determine whether structure inversions for gravity-mode pulsators are feasible. We focus on the case of slowly rotating SPB stars. We computed and analyzed dipole mode kernels for three variables pairs: $(\rho,c), (N^2,c)$, and $(N^2,\rho)$. We assessed the potential of these kernels by predicting the oscillation frequencies of a model after perturbing its structure. We then tested two inversion methods, RLS and SOLA, using a model grid computed with MESA and GYRE. We find that changing the stellar structure affects the oscillation frequencies in a nonlinear way. The oscillation modes for which this nonlinear dependency is the strongest are in resonance with the near-core peak in the buoyancy frequency. The near core region of the star can be probed with SOLA, while RLS requires fine tuning to obtain accurate results. Both RLS and SOLA are strongly affected by the nonlinear dependencies on the structure differences, as these methods are based on a first-order approximation. These inversion methods need to be modified for meaningful applications of inversions to SPB stars. Our results show that inversions of gravity-mode pulsators are possible in principle, but that the typical inversion methods developed for solar-like oscillators are not applicable. [abridged]

by olozhika (Xing Yuchen).

2023-05-17

New submissions for Mon, 12 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 11papers

Work-Life Balance Starts with Proper Deadlines and Exemplary Agencies

Authors: Noé Lugaz, Réka M. Winslow, Nada Al-Haddad, Christina O. Lee, Sarah K. Vines, Katharine Reeves, Amir Caspi, Daniel Seaton, Cooper Downs, Lindsay Glesener, Angelos Vourlidas, Camilla Scolini, Tibor Török, Robert Allen, Erika Palmerio
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); Physics and Society (physics.soc-ph); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2306.05444
Pdf link: https://arxiv.org/pdf/2306.05444
Abstract
Diversity, equity and inclusion (DEI) programs can only be implemented successfully if proper work-life balance is possible in Heliophysics (and in STEM field in general). One of the core issues stems from the culture of "work-above-life" associated with mission concepts, development, and implementation but also the expectations that seem to originate from numerous announcements from NASA (and other agencies). The benefits of work-life balance are well documented; however, the entire system surrounding research in Heliophysics hinders or discourages proper work-life balance. For example, there does not seem to be attention paid by NASA Headquarters (HQ) on the timing of their announcements regarding how it will be perceived by researchers, and how the timing may promote a culture where work trumps personal life. The same is true for remarks by NASA HQ program officers during panels or informal discussions, where seemingly innocuous comments may give a perception that work is expected after "normal" work hours. In addition, we are calling for work-life balance plans and implementation to be one of the criteria used for down-selection and confirmation of missions (Key Decision Points: KDP-B, KDP-C).

Coordinated X-ray and UV absorption within the accretion disk wind of the active galactic nucleus PG 1126-041

Authors: M. Giustini, P. Rodríguez Hidalgo, J. N. Reeves, G. Matzeu, V. Braito, M. Eracleous, G. Chartas, N. Schartel, C. Vignali, P. B. Hall, T. Waters, G. Ponti, D. Proga, M. Dadina, M. Cappi, G. Miniutti, L. de Vries
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.05469
Pdf link: https://arxiv.org/pdf/2306.05469
Abstract
Accretion disk winds launched close to supermassive black holes (SMBHs) are a viable mechanism to provide feedback between the SMBH and the host galaxy. We aim to characterize the X-ray properties of the inner accretion disk wind of the nearby active galactic nucleus (AGN) PG 1126-041, and to study its connection with the ultraviolet (UV)-absorbing wind. We perform spectroscopic analysis of eight XMM-Newton observations of PG 1126-041 taken between 2004 and 2015, using both phenomenological models and the most advanced accretion disk wind models available. For half of the dataset, we can compare the X-ray analysis results with the results of quasi-simultaneous, high-resolution spectroscopic UV observations taken with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope. The X-ray spectra of PG 1126-041 are complex and absorbed by ionized material which is highly variable on multiple time scales, sometimes as short as 11 days. Accretion disk wind models can account for most of the X-ray spectral complexity of PG 1126-041, with the addition of massive clumps, represented by a partially covering absorber. Variations in column density ($N_H \sim 5-20 \times 10^{22}$ cm$^{-2}$) of the partially covering absorber drive the observed X-ray spectral variability of PG 1126-041. The absorption from the X-ray partially covering gas and from the blueshifted C IV troughs appear to vary in a coordinated way. The line of sight toward PG 1126-041 offers a privileged view through a highly dynamic nuclear wind originating on inner accretion disk scales, making the source a very promising candidate for future detailed studies of the physics of accretion disk winds around SMBHs.

FLAMINGO: Calibrating large cosmological hydrodynamical simulations with machine learning

Authors: Roi Kugel, Joop Schaye, Matthieu Schaller, John C. Helly, Joey Braspenning, Willem Elbers, Carlos S. Frenk, Ian G. McCarthy, Juliana Kwan, Jaime Salcido, Marcel P. van Daalen, Bert Vandenbroucke, Yannick M. Bahé, Josh Borrow, Evgenii Chaikin, Filip Huško, Adrian Jenkins, Cedric G. Lacey, Folkert S. J. Nobels, Ian Vernon
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.05492
Pdf link: https://arxiv.org/pdf/2306.05492
Abstract
To fully take advantage of the data provided by large-scale structure surveys, we need to quantify the potential impact of baryonic effects, such as feedback from active galactic nuclei (AGN) and star formation, on cosmological observables. In simulations, feedback processes originate on scales that remain unresolved. Therefore, they need to be sourced via subgrid models that contain free parameters. We use machine learning to calibrate the AGN and stellar feedback models for the FLAMINGO cosmological hydrodynamical simulations. Using Gaussian process emulators trained on Latin hypercubes of 32 smaller-volume simulations, we model how the galaxy stellar mass function and cluster gas fractions change as a function of the subgrid parameters. The emulators are then fit to observational data, allowing for the inclusion of potential observational biases. We apply our method to the three different FLAMINGO resolutions, spanning a factor of 64 in particle mass, recovering the observed relations within the respective resolved mass ranges. We also use the emulators, which link changes in subgrid parameters to changes in observables, to find models that skirt or exceed the observationally allowed range for cluster gas fractions and the stellar mass function. Our method enables us to define model variations in terms of the data that they are calibrated to rather than the values of specific subgrid parameters. This approach is useful, because subgrid parameters are typically not directly linked to particular observables, and predictions for a specific observable are influenced by multiple subgrid parameters.

Investigating the Impact of Metallicity on Star Formation in the Outer Galaxy. I. VLT/KMOS Survey of Young Stellar Objects in Canis Major

Authors: Dominika Itrich, Agata Karska, Marta Sewiło, Lars E. Kristensen, Gregory J. Herczeg, Suzanne Ramsay, William J. Fischer, Benoît Tabone, Will R. M. Rocha, Maciej Koprowski, Ngân Lê, Beata Deka-Szymankiewicz
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.05502
Pdf link: https://arxiv.org/pdf/2306.05502
Abstract
The effects of metallicity on the evolution of protoplanetary disks may be studied in the outer Galaxy where the metallicity is lower than in the solar neighbourhood. We present the VLT/KMOS integral field spectroscopy in the near-infrared of $\sim$120 candidate young stellar objects (YSOs) in the CMa-$\ell$224 star-forming region located at a Galactocentric distance of 9.1 kpc. We characterise the YSO accretion luminosities and accretion rates using the hydrogen Br$\gamma$ emission and find the median accretion luminosity of $\log{(L_{\rm acc})} = -0.82^{+0.80}{-0.82} L\odot$. Based on the measured accretion luminosities, we investigate the hypothesis of star formation history in the CMa-$\ell$224. Their median values suggest that Cluster C, where most of YSO candidates have been identified, might be the most evolved part of the region. The accretion luminosities are similar to those observed toward low-mass YSOs in the Perseus and Orion molecular clouds, and do not reveal the impact of lower metallicity. Similar studies in other outer Galaxy clouds covering a wide range of metallicities are critical to gain a complete picture of star formation in the Galaxy.

The VISCACHA survey -- VII. Assembly history of the Magellanic Bridge and SMC Wing from star clusters

Authors: R. A. P. Oliveira, F. F. S. Maia, B. Barbuy, B. Dias, J. F. C. Santos Jr., S. O. Souza, L. O. Kerber, E. Bica, D. Sanmartim, B. Quint, L. Fraga, T. Armond, D. Minniti, M. C. Parisi, O. J. Katime Santrich, M. S. Angelo, A. Pérez-Villegas, B. J. De Bórtoli
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.05503
Pdf link: https://arxiv.org/pdf/2306.05503
Abstract
The formation scenario of the Magellanic Bridge during an encounter between the Large and Small Magellanic Clouds $\sim200,$Myr ago, as proposed by $N$-body models, would be imprinted in the chemical enrichment and kinematics of its stars, and sites of ongoing star formation along its extension. We present an analysis of 33 Bridge star clusters using photometry obtained with the SOAR 4-m telescope equipped with adaptive optics for the VISCACHA survey. We performed a membership selection and derived self-consistent ages, metallicities, distances and reddening values via statistical isochrone fitting, as well as tidal radii and integrated masses from structure analysis. Two groups are clearly detected: 13 well-studied clusters older than the Bridge, with $0.5-6.8,$Gyr and $\rm{[Fe/H]}<-0.6,$dex; and 15 clusters with $< 200,$Myr and $\rm{[Fe/H]}>-0.5,$dex, probably formed in-situ. The old clusters follow the overall age and metallicity gradients of the SMC, whereas the younger ones are uniformly distributed along the Bridge. The main results are as follows: $(i)$ we derive ages and metallicities for the first time for 9 and 18 clusters, respectively; $(ii)$ we detect two metallicity dips in the age-metallicity relation of the Bridge at $\sim 200,$Myr and $1.5,$Gyr ago for the first time, possibly chemical signatures of the formation of the Bridge and Magellanic Stream; $(iii)$ we estimate a minimum stellar mass for the Bridge of $3-5 \times 10^5,M_\odot$; $(iv)$ we confirm that all the young Bridge clusters at $\rm{RA} < 3^h$ are metal-rich $\rm{[Fe/H]} \sim -0.4,$dex.

Binning is Sinning: Redemption for Hubble Diagram using Photometrically Classified Type Ia Supernovae

Authors: Richard Kessler, Maria Vincenzi, Patrick Armstrong
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.05819
Pdf link: https://arxiv.org/pdf/2306.05819
Abstract
Bayesian Estimation Applied to Multiple Species (BEAMS) has been implemented in the BEAMS with Bias Corrections (BBC) framework to produce a redshift-binned Hubble diagram (HD) for Type Ia Supernovae (SN Ia). The BBC method corrects for selection effects and non-SNIa contamination, and systematic uncertainties are described by a covariance matrix with dimension matching the number of BBC redshift bins. For spectroscopically confirmed SNIa samples, a recent "Binning is Sinning" article (BHS21, arxiv:2012.05900) showed that an unbinned HD and covariance matrix reduces the systematic uncertainty by a factor of 1.5 compared to the binned approach. Here we extend their analysis to obtain an unbinned HD for a photometrically identified sample processed with BBC. To test this new method, we simulate and analyze 50 samples corresponding to the Dark Energy Survey (DES) with a low-redshift anchor; the simulation includes SNe Ia, and contaminants from core collapse SNe and peculiar SNe Ia. The analysis includes systematic uncertainties for calibration, and measures the dark energy equation of state parameter (w). Compared to a redshift-binned HD, the unbinned HD with nearly 2,000 events results in a smaller systematic uncertainty, in qualitative agreement with BHS21, and averaging results among the 50 samples we find no evidence for bias in measured cosmological parameters. To reduce computation time for fitting an unbinned HD with large samples, we propose an HD-rebinning method that defines the HD in bins of redshift, color, and stretch; the rebinned HD results in similar uncertainty as the unbinned case, and shows no evidence for biased cosmology parameters.

SRG/eROSITA X-ray shadowing study of giant molecular clouds

Authors: Michael C. H. Yeung, Michael J. Freyberg, Gabriele Ponti, Konrad Dennerl, Manami Sasaki, Andy Strong
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.05858
Pdf link: https://arxiv.org/pdf/2306.05858
Abstract
SRG/eROSITA is situated in a halo orbit around L2 where the highly variable solar wind charge exchange (SWCX) emission from Earth's magnetosheath is expected to be negligible. The soft X-ray foreground emissions from the local hot bubble (LHB) and the remaining heliospheric SWCX emissions could be studied in unprecedented detail with eROSITA All-Sky Survey (eRASS) data in a 6-month cadence and better spectral resolution than ROSAT. We aim to use eRASS data of the sight lines towards three giant molecular clouds away from the Galactic plane to isolate and study the soft X-ray diffuse foreground emission. These X-ray shadows will serve as calibration baselines for the future three-dimensional structural study of the LHB. We conducted spectral analysis on the diffuse X-ray spectra of these clouds from the first four eRASSs to estimate and separate the heliospheric SWCX contribution from the LHB emission. We find the density of the LHB to be independent of the sight line with $n_e \sim 4 \times 10^{-3},$cm$^{-3}$, but not the temperature. We report a lower temperature of $kT_{\mathrm{LHB}}=0.084\pm0.004,$keV towards Chamaeleon$~~$II & III (Cha$~~$II & III) than Ophiuchus (Oph) and Corona Australis (CrA), in which we measured $0.102\pm0.006$ and $0.112\pm0.009,$keV, respectively. We measured the emission measure of the LHB to be $\sim 2\times10^{-3},$cm$^{-6},$pc at medium Galactic latitudes ($|b| \sim 20^{\circ}$). A monotonic increase in the SWCX contribution has been observed since the start of 2020, coincidental with the beginning of solar cycle 25. For Oph, SWCX has dominated the LHB in the $0.3$-$0.7,$keV band intensity since eRASS2. We observed lower SWCX contributions in Cha$~$II & III and CrA, consistent with the expected decreasing solar wind ion density at high heliographic latitudes.

Numerical simulations of relativistic jets

Authors: Manel Perucho, Jose López-Miralles
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.05864
Pdf link: https://arxiv.org/pdf/2306.05864
Abstract
In this paper, we review recent and ongoing work by our group on numerical simulations of relativistic jets. Relativistic outflows in Astrophysics are related to dilute, high energy plasmas, with physical conditions out of the reach of current laboratory capabilities. Simulations are thus imperative for the study of these objects. We present a number of such scenarios that have been studied by our group at the Universitat de Val`encia. In particular, we have focused on the evolution of extragalactic outflows through galactic and intergalactic environments, deceleration by interaction with stars or clouds, or the propagation of jets in X-ray binaries and interaction with stellar winds from massive companions. All also share their role as particle acceleration sites and production of non-thermal radiation throughout the electromagnetic spectrum. Therefore, our work is not only aimed to understand the impact of outflows on their environments and thus their role in galaxy and cluster evolution, but also the nature and capabilities of these sites as generators of high and very-high energy radiation and cosmic rays.

Ohmic dissipation during the formation of super-Earth

Authors: Shi Jia, Wei Zhong, Cong Yu
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.05913
Pdf link: https://arxiv.org/pdf/2306.05913
Abstract
Super-Earth population, as one of the representatives of exoplanets, plays an important role in constraining the planet formation theories. According to the prediction from core-accretion models, super-Earths should be rare because their masses are in the range of the critical mass above which they would grow to be gas giants by runaway gas accretion. In this work, we investigate the effect of ohmic dissipation on the planetary thermal structure and cooling contraction as planets accrete gas from their surrounding disks. We find that the extra heating energy from Ohmic heating deposited into planetary envelopes can push the planetary radiative-convective boundaries inward and prevent the planets from cooling, and can even halt accretion. We explore parameter space to study the dependence of cooling timescale on the input parameters of the ohmic-dissipation model. Numerical results show that gas accretion can be halted before runaway gas accretion and the envelope mass is only several percent of planetary core mass for some parameter sets. Our results suggest that ohmic dissipation is a potential mechanism to delay the gas accretion and promote the formation of super-Earths. Future observations may help to constrain the importance of ohmic dissipation on the super-Earth formation.

Redeveloping a CLEAN Deconvolution Algorithm for Scatter-Broadened Radio Pulsar Signals

Authors: Olivia Young, Michael Lam
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.06046
Pdf link: https://arxiv.org/pdf/2306.06046
Abstract
Broadband radio waves emitted from pulsars are distorted and delayed as they propagate toward the Earth due to interactions with the free electrons that compose the interstellar medium, with lower radio frequencies being more impacted than higher frequencies. Multipath propagation in the interstellar medium results in both later times of arrival for the lower frequencies and causes the observed pulse to arrive with a broadened tail described via the pulse broadening function. We employ the CLEAN deconvolution technique to recover both the intrinsic pulse shape and pulse broadening function. This work expands upon previous descriptions of CLEAN deconvolution used in pulse broadening analyses by parameterizing the efficacy on simulated data and developing a suite of tests to establish which of a set of figures of merit lead to an automatic and consistent determination of the scattering timescale and its uncertainty. We compare our algorithm to simulations performed on cyclic spectroscopy estimates of the scattering timescale. We test our improved algorithm on the highly scattered millisecond pulsar J1903+0327, showing the scattering timescale to change over years, consistent with estimates of the refractive timescale of the pulsar.

Ion-Driven Instabilities in the Inner Heliosphere II: Classification and Multi-Dimensional Mapping

Authors: Mihailo M. Martinovic, Kristopher G. Klein
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2306.06060
Pdf link: https://arxiv.org/pdf/2306.06060
Abstract
Linear theory is a well developed framework for characterizing instabilities in weakly collisional plasmas, such as the solar wind. In the previous instalment of this series, we analyzed ~1.5M proton and alpha particle Velocity Distribution Functions (VDFs) observed by Helios I and II to determine the statistical properties of the standard instability parameters such as the growth rate, frequency, the direction of wave propagation, and the power emitted or absorbed by each component, as well as to characterize their behavior with respect to the distance from the Sun and collisional processing. In this work, we use this comprehensive set of instability calculations to train a Machine Learning algorithm consisting of three interlaced components that: 1) predict if an interval is unstable from observed VDF parameters; 2) predict the instability properties for a given unstable VDF; and 3) classify the type of the unstable mode. We use these methods to map the properties in multi-dimensional phase space to find that the parallel-propagating, proton-core-induced Ion Cyclotron mode dominates the young solar wind, while the oblique Fast Magnetosonic mode regulates the proton beam drift in the collisionally old plasma.

by olozhika (Xing Yuchen).

2023-06-12

New submissions for Fri, 12 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-12

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 7papers

Internal Gravity Waves in Massive Stars II: Frequency Analysis Across Stellar Mass

Authors: R. P. Ratnasingam, T. M. Rogers, S. Chowdhury, G. Handler, R. Vanon, A. Varghese, P. V. F. Edelmann
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.06379
Pdf link: https://arxiv.org/pdf/2305.06379
Abstract
Stars with masses above 1.6 solar masses generally possess convective cores and radiative envelopes, which allows the propagation of outward-travelling internal gravity waves. We have studied the generation and propagation of IGWs in such stars using two-dimensional, fully nonlinear hydrodynamical simulations with realistic stellar reference states from the one-dimensional stellar evolution code, Modules for Stellar Astrophysics. Compared to previous similar works, this study utilises radius-dependent thermal diffusivity profiles for 5 different stellar masses at the middle of main sequence: 3 - 13 solar masses. From the simulations, we find that the surface perturbations are larger for higher masses, but no noticeable trends are observed for the frequency slopes with different stellar masses. The slopes are also similar to the results from previous works. We compare our simulation results with stellar photometric data from a recent survey and find that for frequency intervals above 8 microHz, there is a good agreement between the temperature frequency slopes from the simulations and the surface brightness variations of these observed stars, indicating that the brightness variations are caused by core-generated IGWs.

How to Flip a Bar

Authors: Angela Collier, Ann-Marie Madigan
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.06383
Pdf link: https://arxiv.org/pdf/2305.06383
Abstract
Galactic bars, made up of elongated and aligned stellar orbits, can lose angular momentum via resonant torques with dark matter particles in the halo and slow down. Here we show that if a stellar bar is decelerated to zero rotation speed, it can flip the sign of its angular momentum and reverse rotation direction. We demonstrate this in a collisionless N-body simulation of a galaxy in a live counter-rotating halo. Reversal begins at small radii and propagates outward. The flip generates a kinematically-decoupled core both in the visible galaxy and in the dark matter halo, and counter-rotation generates a large-scale warp of the outer disk with respect to the bar.

Time evolution of Ce as traced by APOGEE using giant stars observed with the Kepler, TESS and K2 missions

Authors: G. Casali, V. Grisoni, A. Miglio, C. Chiappini, M. Matteuzzi, L. Magrini, E. Willett, G. Cescutti, F. Matteucci, A. Stokholm, M. Tailo, J. Montalban, Y. Elsworth, B. Mosser
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.06396
Pdf link: https://arxiv.org/pdf/2305.06396
Abstract
Abundances of s-capture process elements in stars with exquisite asteroseismic, spectroscopic, and astrometric constraints offer a novel opportunity to study stellar evolution, nucleosynthesis, and Galactic chemical evolution. We aim to investigate one of the least studied s-process elements in the literature, Ce, using stars with asteroseismic constraints from the Kepler, K2 and TESS missions. We combine the global asteroseismic parameters derived from precise light curves obtained by the Kepler, K2 and TESS missions with chemical abundances from the APOGEE DR17 survey and astrometric data from the Gaia mission. Finally, we compute stellar ages using the code PARAM. We investigate the different trends of [Ce/Fe] as a function of [Fe/H], [alpha/Fe] and age considering the dependence on the radial position, specially in the case of K2 targets which cover a large Galactocentric range. We, finally, explore the [Ce/alpha] ratios as a function of age in different Galactocentric intervals. The studied trends display a strong dependence of the Ce abundances on [Fe/H] and star formation history. Indeed, the [Ce/Fe] ratio shows a non-monotonic dependence on [Fe/H] with a peak around -0.2 dex. Moreover, younger stars have higher [Ce/Fe] and [Ce/alpha] ratios than older stars, confirming the latest contribution of low- and intermediate-mass asymptotic giant branch stars to the Galactic chemical enrichment. In addition, the trends of [Ce/Fe] and [Ce/alpha] with age become steeper moving towards the outer regions of the Galactic disc, demonstrating a more intense star formation in the inner regions than in the outer regions. Ce is thus a potentially interesting element to help constraining stellar yields and the inside-out formation of the Milky Way disc. However, the large scatter in all the relations studied here, suggests that spectroscopic uncertainties for this element are still too large.

A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions

Authors: Christian I. Johnson, Annalisa Calamida, Justin A. Kader, Ivan Ferraro, Catherine A. Pilachowski, Giuseppe Bono, Alessandra Mastrobuono-Battisti, Armin Rest, Alfredo Zenteno, Alice Zocchi
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.06419
Pdf link: https://arxiv.org/pdf/2305.06419
Abstract
Wide-field and deep DECam multi-band photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar sub-populations and stars in different evolutionary phases out to the cluster tidal radius. We used the C_ugi = (u-g)-(g-i) index to identify three chemically distinct sub-populations along the red giant branch and compared their spatial distributions. The most light-element enriched sub-population (P3) is more centrally concentrated; however, it shows a more extended distribution in the external regions of the cluster compared to the primordial (P1) and intermediate (P2) composition populations. Furthermore, the P3 sub-population centroid is off-center relative to those of the P1 and P2 groups. We also analyzed the spatial distribution of horizontal branch stars and found that the relative fraction of red horizontal branch stars increases for radial distances larger than ~ 1.5' while that of the blue and hotter stars decreases. These new observations, combined with literature spectroscopic measurements, suggest that the red horizontal branch stars are the progeny of all the stellar sub-populations in NGC 2808, i.e. primordial and light-element enhanced, while the blue stars are possibly the result of a combination of the "hot-flasher" and the "helium-enhanced" scenarios. A similar distribution of different red giant branch sub-populations and horizontal branch stars was also found for the most massive Galactic globular cluster, omega Cen, based on combined DECam and HST data, which suggests the two may share a similar origin.

Interpreting the GeV-TeV Gamma-Ray Spectra of Local Giant Molecular Clouds using GEANT4 Simulation

Authors: Abhijit Roy, Jagdish C. Joshi, Martina Cardillo, Ritabrata Sarkar
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.06693
Pdf link: https://arxiv.org/pdf/2305.06693
Abstract
Recently, the Fermi-LAT gamma-ray satellite has detected six Giant Molecular Clouds (GMCs) located in the Gould Belt and the Aquila Rift regions. In half of these objects (Taurus, Orion A, Orion B), the observed gamma-ray spectrum can be explained using the Galactic diffused Cosmic Ray (CR) interactions with the gas environments. In the remaining three GMCs (Rho Oph, Aquila Rift, Cepheus), the origin of the gamma-ray spectrum is still not well established. We use the GEometry ANd Tracking (GEANT4) simulation framework in order to simulate gamma-ray emission due to CR/GMC interaction in these three objects, taking into account the gas density distribution inside the GMCs. We find that propagation of diffused Galactic CRs inside these GMCs can explain the Fermi-LAT detected gamma-ray spectra. Further, our estimated TeV-PeV fluxes are consistent with the HAWC upper limits, available for the Aquila Rift GMC. As last step, we compute the total neutrino flux estimated for these GMCs and compare it with the IceCube detection sensitivity.

Doppler wind measurements in Neptune's stratosphere with ALMA

Authors: Óscar Carrión-González, Raphael Moreno, Emmanuel Lellouch, Thibault Cavalié, Sandrine Guerlet, Gwenaël Milcareck, Aymeric Spiga, Noé Clément, Jérémy Leconte
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.06787
Pdf link: https://arxiv.org/pdf/2305.06787
Abstract
Neptune's tropospheric winds are among the most intense in the Solar System, but the dynamical mechanisms that produce them remain uncertain. Measuring wind speeds at different pressure levels may help understand the atmospheric dynamics of the planet. The goal of this work is to directly measure winds in Neptune's stratosphere with ALMA Doppler spectroscopy. We derived the Doppler lineshift maps of Neptune at the CO(3-2) and HCN(4-3) lines at 345.8 GHz ($\lambda$~0.87 mm) and 354.5 GHz (0.85 mm), respectively. For that, we used spectra obtained with ALMA in 2016 and recorded with a spatial resolution of ~0.37" on Neptune's 2.24" disk. After subtracting the planet solid rotation, we inferred the contribution of zonal winds to the measured Doppler lineshifts at the CO and HCN lines. We developed an MCMC-based retrieval methodology to constrain the latitudinal distribution of wind speeds. We find that CO(3-2) and HCN(4-3) lines probe the stratosphere of Neptune at pressures of $2^{+12}{-1.8}$ mbar and $0.4^{+0.5}{-0.3}$ mbar, respectively. The zonal winds at these altitudes are less intense than the tropospheric winds based on cloud tracking from Voyager observations. We find equatorial retrograde (westward) winds of $-180^{+70}{-60}$ m/s for CO, and $-190^{+90}{-70}$ m/s for HCN. Wind intensity decreases towards mid-latitudes, and wind speeds at 40$^\circ$S are $-90^{+50}{-60}$ m/s for CO, and $-40^{+60}{-80}$ m/s for HCN. Wind speeds become 0 m/s at about 50$^\circ$S, and we find that the circulation reverses to a prograde jet southwards of 60$^\circ$S. Overall, our direct stratospheric wind measurements match previous estimates from stellar occultation profiles and expectations based on thermal wind equilibrium. These are the first direct Doppler wind measurements performed on the Icy Giants, opening a new method to study and monitor their stratospheric dynamics.

Merger Conditions of Population III Protostar Binaries

Authors: Takanobu Kirihara, Hajime Susa, Takashi Hosokawa, Tomoya Kinugawa
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.06843
Pdf link: https://arxiv.org/pdf/2305.06843
Abstract
Massive close binary stars with extremely small separations have been observed, and they are possible progenitors of gravitational-wave sources. The evolution of massive binaries in the protostellar accretion stage is key to understanding their formation process. We, therefore, investigate how close the protostars, consisting of a high-density core and a vast low-density envelope, can approach each other but not coalesce. To investigate the coalescence conditions, we conduct smoothed particle hydrodynamics simulations following the evolution of equal-mass binaries with different initial separations. Since Population (Pop) I and III protostars have similar interior structures, we adopt a specific PopIII model with the mass and radius of $7.75;M_{\odot}$ and $61.1;R_{\odot}$ obtained by the stellar evolution calculations. Our results show that the binary separation decreases due to the transport of the orbital angular momentum to spin angular momentum. If the initial separation is less than about 80 percent of the sum of the protostellar radius, the binary coalesces in a time shorter than the tidal lock timescale. The mass loss up to the merging is $\lesssim 3$ per~cent. After coalescence, the star rotates rapidly, and its interior structure is independent of the initial separation. We conclude that there must be some orbital shrinking mechanism after the protostars contract to enter the zero-age main-sequence stage.

New submissions for Wed, 7 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 10papers

How the dynamical properties of globular clusters impact their $γ$-ray and X-ray emission

Authors: Raniere de Menezes, Federico Di Pierro, Andrea Chiavassa
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.03131
Pdf link: https://arxiv.org/pdf/2306.03131
Abstract
The X-ray and $\gamma$-ray emission of globular clusters (GCs) is attributed to their large fraction of compact binary systems, especially those with millisecond pulsars (MSPs). We analyze a population of 124 Galactic GCs to investigate how their dynamical properties affect the formation and evolution of compact binary systems and how this can be translated into the clusters' observed X-ray and $\gamma$-ray emission. We use mainly Chandra X-ray Observatory and Fermi Large Area Telescope observations to achieve our goals and start by detecting 39 GCs in $\gamma$ rays, seven of which are not listed in previous Fermi-LAT catalogs. Additionally, we find that the total number of X-ray sources within a GC and its $\gamma$-ray luminosity are linearly correlated with the stellar encounter rate, indicating that compact binary systems are mainly formed via close stellar encounters. We also find an unexpected rise in the number of X-ray sources for GCs with low rates of stellar encounters, suggesting that there is a dynamical threshold where the formation of X-ray sources is dominated by stellar encounters. Furthermore, we use the Heggie-Hills law to find that subsequent stellar encounters in these compact binaries will, on average, make the binaries even harder, with basically no possibility of binary ionization. Finally, we find that all GCs are point-like sources in $\gamma$ rays, indicating that the MSPs are concentrated in the clusters' cores, likely due to dynamical friction.

A Crystallizing White Dwarf in a Sirius-Like Quadruple System

Authors: Alexander Venner, Simon Blouin, Antoine Bédard, Andrew Vanderburg
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.03140
Pdf link: https://arxiv.org/pdf/2306.03140
Abstract
The observational signature of core crystallization of white dwarfs has recently been discovered. However, the magnitude of the crystallization-powered cooling delay required to match observed white dwarfs is larger than predicted by conventional models, requiring additional mechanisms of energy release in white dwarf interiors. The most ideal benchmarks for understanding this discrepancy would be bright and nearby crystallizing white dwarfs with total ages that can be externally constrained. In this work we report that a recently discovered white dwarf is a bound companion to the triple star HD 190412, forming a new Sirius-like system in the solar neighbourhood. The location of HD 190412 C on the $T_{\text{eff}}-\text{mass}$ diagram implies it is undergoing crystallization, making this the first confirmed crystallizing white dwarf whose total age can be externally constrained. Motivated by the possibility that a cooling delay caused by crystallization can be directly detected for this white dwarf we employ a variety of methods to constrain the age of the system; however, our empirical age anomaly of $+3.1\pm1.9$ Gyr is ultimately too imprecise to reach statistical significance, preventing us from making strong constraints to models of white dwarf crystallization. Our results are nonetheless compatible with the recent hypothesis that $^{22}$Ne phase separation is responsible for the excess cooling delay of crystallizing white dwarfs. The discovery of this system at only 32 parsecs suggests that similar benchmark systems are likely to be common; future discoveries may therefore provide powerful tests for models of white dwarf crystallization.

Many Roads Lead to Lithium: Formation Pathways For Lithium-Rich Red Giants

Authors: Maryum Sayeed, Melissa K. Ness, Benjamin T. Montet, Matteo Cantiello, Andrew R. Casey, Sven Buder, Megan Bedell, Katelyn Breivik, Brian D. Metzger, Sarah L. Martell, Leah McGee-Gold
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.03323
Pdf link: https://arxiv.org/pdf/2306.03323
Abstract
Stellar models predict that lithium (Li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are Li-rich. We aim to uncover possible origins of this population, by analysing 1155 Li-rich giants (A(Li) $\geq$ 1.5) in GALAH DR3. To expose peculiar traits of Li-rich stars, we construct a reference sample of Li-normal (doppelg"anger) stars with matched evolutionary state and fiducial supernova abundances. Comparing Li-rich and doppelg"anger spectra reveals systematic differences in the H-$\alpha$ and Ca-triplet line profiles associated with the velocity broadening measurement. We also find twice as many Li-rich stars appear to be fast rotators (2% with $v_\textrm{broad} \gtrsim 20$ km s$^{-1}$) compared to doppelg"angers. On average, Li-rich stars have higher abundances than their doppelg"angers, for a subset of elements, and Li-rich stars at the base of RGB have higher mean $s-$process abundances ($\geq 0.05$ dex for Ba, Y, Zr), relative to their doppelg"angers. External mass-transfer from intermediate-mass AGB companions could explain this signature. Additional companion analysis excludes binaries with mass ratios $\gtrsim$ 0.5 at $\gtrsim$ 7 AU. We also discover that highly Ba-enriched stars are missing from the Li-rich population, possibly due to low-mass AGB companions which preclude Li-enrichment. Finally, we confirm a prevalence of Li-rich stars on the red clump that increases with lithium, which supports an evolutionary state mechanism for Li-enhancement. Multiple culprits, including binary spin-up and mass-transfer, are therefore likely mechanisms of Li-enrichment.

First Detection of A Linear Structure in the Midplane of the Young HH 211 Protostellar Disk: A Spiral Arm?

Authors: Chin-Fei Lee, Kai-Syun Jhan, Anthony Moraghan
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.03342
Pdf link: https://arxiv.org/pdf/2306.03342
Abstract
Spiral structures have been detected in evolved protostellar disks, driving the disk accretion towards the central protostars to facilitate star formation. However, it is still unclear if these structures can form earlier in young protostellar disks. With the Atacama Large Millimeter/submillimeter Array (ALMA), we have detected and spatially resolved a very young and nearly edge-on dusty disk with a radius of only ~ 20 au in the HH 211 protostellar system at submillimeter wavelength. It is geometrically thick, indicating that the submillimeter light-emitting dust grains have yet to settle to the midplane for planet formation. Intriguingly, it shows 3 bright linear structures parallel to the equatorial plane, resembling a 3-layer pancake that has not been seen before. The top and bottom ones arise from the warm disk surfaces, unveiling the flared structure of the disk. More importantly, the middle one is in the dense midplane of the disk and can be modeled as a trailing spiral arm excited by disk gravity, as seen in evolved protostellar disks, supporting the presence of spiral structures in the very early phase for disk accretion.

Simulations of idealised 3D atmospheric flows on terrestrial planets using LFRic-Atmosphere

Authors: Denis E. Sergeev, Nathan J. Mayne, Thomas Bendall, Ian A. Boutle, Alex Brown, Iva Kavcic, James Kent, Krisztian Kohary, James Manners, Thomas Melvin, Enrico Olivier, Lokesh K. Ragta, Ben J. Shipway, Jon Wakelin, Nigel Wood, Mohamed Zerroukat
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Arxiv link: https://arxiv.org/abs/2306.03614
Pdf link: https://arxiv.org/pdf/2306.03614
Abstract
We demonstrate that LFRic-Atmosphere, a model built using the Met Office's GungHo dynamical core, is able to reproduce idealised large-scale atmospheric circulation patterns specified by several widely-used benchmark recipes. This is motivated by the rapid rate of exoplanet discovery and the ever-growing need for numerical modelling and characterisation of their atmospheres. Here we present LFRic-Atmosphere's results for the idealised tests imitating circulation regimes commonly used in the exoplanet modelling community. The benchmarks include three analytic forcing cases: the standard Held-Suarez test, the Menou-Rauscher Earth-like test, and the Merlis-Schneider Tidally Locked Earth test. Qualitatively, LFRic-Atmosphere agrees well with other numerical models and shows excellent conservation properties in terms of total mass, angular momentum and kinetic energy. We then use LFRic-Atmosphere with a more realistic representation of physical processes (radiation, subgrid-scale mixing, convection, clouds) by configuring it for the four TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI) scenarios. This is the first application of LFRic-Atmosphere to a possible climate of a confirmed terrestrial exoplanet. LFRic-Atmosphere reproduces the THAI scenarios within the spread of the existing models across a range of key climatic variables. Our work shows that LFRic-Atmosphere performs well in the seven benchmark tests for terrestrial atmospheres, justifying its use in future exoplanet climate studies.

Wobbling jets in common envelope evolution

Authors: Noam Dori, Ealeal Bear, Noam Soker (Technion, Israel)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.03618
Pdf link: https://arxiv.org/pdf/2306.03618
Abstract
We find that the convective motion in the envelopes of red supergiant (RSG) stars supplies a non-negligible stochastic angular momentum to the mass that a secondary star accretes in a common envelope evolution (CEE), such that jets that the secondary star launches wobble. The orbital motion of the secondary star in a CEE and the density gradient in the envelope impose a non-zero angular momentum to the accreted mass with a constant direction parallel to the orbital angular momentum. From one-dimensional stellar evolution simulations with the numerical code \textsc{mesa} we find that the stochastic convection motion in the envelope of RSG stars adds a stochastic angular momentum component with an amplitude that is about 0.1-1 times that of the constant component due to the orbital motion. We mimic a CEE of the RSG star by removing envelope mass at a high rate and by depositing energy into its envelope. The stochastic angular momentum implies that the accretion disk around the secondary star (which we do not simulate), and therefore the jets that it launches, wobble with angles of up to tens of degrees with respect to the orbital angular momentum axis. This wobbling makes it harder for jets to break out from the envelope and can shape small bubbles in the ejecta that compress filaments that appear as arcs in the ejected nebula, i.e., in planetary nebulae when the giant is an asymptotic giant branch star.

Young Stellar Object Candidates in IC 417

Authors: L. M. Rebull, R. L. Anderson III, G. Hall, J. D. Kirkpatrick, X. Koenig, C. E. Odden, B. Rodriguez, R. Sanchez, B. Senson, V. Urbanowski, M. Austin, K. Blood, E. Kerman, J. Long, N. Roosa
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.03728
Pdf link: https://arxiv.org/pdf/2306.03728
Abstract
IC 417 is in the Galactic Plane, and likely part of the Aur OB2 association; it is ~2 kpc away. Stock 8 is one of the densest cluster constituents; off of it to the East, there is a 'Nebulous Stream' (NS) that is dramatic in the infrared (IR). We have assembled a list of literature-identified young stellar objects (YSOs), new candidate YSOs from the NS, and new candidate YSOs from IR excesses. We vetted this list via inspection of the images, spectral energy distributions (SEDs), and color-color/color-magnitude diagrams. We placed the 710 surviving YSOs and candidate YSOs in ranked bins, nearly two-thirds of which have more than 20 points defining their SEDs. The lowest-ranked bins include stars that are confused, or likely carbon stars. There are 503 in the higher-ranked bins; half are SED Class III, and $\sim$40% are SED Class II. Our results agree with the literature in that we find that the NS and Stock 8 are at about the same distance as each other (and as the rest of the YSOs), and that the NS is the youngest region, with Stock 8 a little older. We do not find any evidence for an age spread within the NS, consistent with the idea that the star formation trigger came from the north. We do not find that the other literature-identified clusters here are as young as either the NS or Stock 8; at best they are older than Stock 8, and they may not all be legitimate clusters.

A Chondritic Solar Neighborhood

Authors: Isabella L. Trierweiler, Alexandra E. Doyle, Edward D. Young
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.03743
Pdf link: https://arxiv.org/pdf/2306.03743
Abstract
A persistent question in exoplanet demographics is whether exoplanetary systems form from similar compositional building blocks to our own. Polluted white dwarf stars offer a unique way to address this question as they provide measurements of the bulk compositions of exoplanetary material. We present a statistical analysis of the rocks polluting oxygen-bearing white dwarfs and compare their compositions to rocks in the Solar System. We find that the majority of the extrasolar rocks are consistent with the composition of typical chondrites. Measurement uncertainties prevent distinguishing between chondrites and bulk Earth, but do permit detecting the differences between chondritic compositions and basaltic or continental crust. We find no evidence of crust amongst the polluted white dwarfs. We show that the chondritic nature of extrasolar rocks is also supported by the compositions of local stars. While galactic chemical evolution results in variations in the relative abundances of rock-forming elements spatially and temporally on galaxy-wide scales, the current sample of polluted white dwarfs are sufficiently young and close to Earth that they are not affected by this process. We conclude that exotic compositions are not required to explain the majority of observed rock types around polluted white dwarfs, and that variations between exoplanetary compositions in the stellar neighborhood are generally not due to significant differences in the initial composition of protoplanetary disks. Nonetheless, there is evidence from stellar observations that planets formed in the first several billion years in the Galaxy have lower metal core fractions compared with Earth on average.

High energy cosmic rays and gamma rays from star clusters: the case of Cygnus OB2

Authors: Pasquale Blasi (GSSI), Giovanni Morlino (INAF)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.03762
Pdf link: https://arxiv.org/pdf/2306.03762
Abstract
We investigate the acceleration of cosmic rays at the termination shock that results from the interaction of the collective wind of star clusters with the surrounding interstellar medium. The solution of the transport equation of accelerated particles in the wind-excavated cavity, including energy losses due to CR interactions with neutral gas in the bubble, shows several interesting properties that are discussed in detail. The issue of the maximum energy of the accelerated particles is discussed with special care, because of its implications for the origin of Galactic cosmic rays. Gamma ray emission is produced in the cavity due to inelastic pp scattering, while accelerated particles are advected downstream of the termination shock and diffuse at the same time. Both the spectrum and the morphology of such emission are discussed, with a comparison of our results with the observations of gamma ray emission from the Cygnus OB2 region.

Reinterpreting the Polluted White Dwarf SDSS J122859.93+104032.9 in Light of Thermohaline Mixing Models: More Polluting Material from a Larger Orbiting Solid Body

Authors: Arianna Dwomoh, Evan B. Bauer
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.03864
Pdf link: https://arxiv.org/pdf/2306.03864
Abstract
The polluted white dwarf (WD) system SDSS J122859.93+104032.9 (SDSS J1228) shows variable emission features interpreted as originating from a solid core fragment held together against tidal forces by its own internal strength, orbiting within its surrounding debris disk. Estimating the size of this orbiting solid body requires modeling the accretion rate of the polluting material that is observed mixing into the WD surface. That material is supplied via sublimation from the surface of the orbiting solid body. The sublimation rate can be estimated as a simple function of the surface area of the solid body and the incident flux from the nearby hot WD. On the other hand, estimating the accretion rate requires detailed modeling of the surface structure and mixing in the accreting WD. In this work, we present MESA WD models for SDSS J1228 that account for thermohaline instability and mixing in addition to heavy element sedimentation to accurately constrain the sublimation and accretion rate necessary to supply the observed pollution. We derive a total accretion rate of $\dot M_{\rm acc}=1.8\times 10^{11},\rm g,s^{-1}$, several orders of magnitude higher than the $\dot M_{\rm acc}=5.6\times 10^{8},\rm g,s^{-1}$ estimate obtained in earlier efforts. The larger mass accretion rate implies that the minimum estimated radius of the orbiting solid body is r$_{\rm{min}}$ = 72 km, which, although significantly larger than prior estimates, still lies within upper bounds (a few hundred km) for which the internal strength could no longer withstand tidal forces from the gravity of the WD.

by olozhika (Xing Yuchen).

2023-06-07

New submissions for Wed, 3 May 23

Update Star Formation & Molecular Cloud papers at 2am UTC (10am Beijing time) every weekday.
forked from zhuhu00/Paper-Daily-Notice.
2023-05-03

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 10papers

Self-similar growth of Bose stars

Authors: A.S. Dmitriev, D.G. Levkov, A.G. Panin, I.I. Tkachev
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2305.01005
Pdf link: https://arxiv.org/pdf/2305.01005
Abstract
We analytically solve the problem of Bose star growth in the bath of gravitationally interacting particles. We find that after nucleation of this object, the bath is described by a self-similar solution of the kinetic equation, which is an attractor. Together with the conservation laws, this fixes mass evolution of the Bose star. Our results explain slowdown of the star growth at a certain "core-halo" mass, but also predict formation of the heavier and lighter objects in magistral dark matter models.

Updated Inventory of Carbon Monoxide in The Taurus Molecular Cloud

Authors: Yan Duan, Di Li, Laurent Pagani, Paul F. Goldsmith, Tao-Chung Ching, Chen Wang, Jinjin Xie
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.01112
Pdf link: https://arxiv.org/pdf/2305.01112
Abstract
The most extensive survey of carbon monoxide (CO) gas in the Taurus molecular cloud relied on $^{12}$CO and $^{13}$CO $J=1 \rightarrow 0$ emission only, distinguishing the region where $^{12}$CO is detected without $^{13}$CO (named mask 1 region) from the one where both are detected (mask 2 region). We have taken advantage of recent $^{12}$CO $J=3\rightarrow2$ JCMT observations where they include mask 1 regions to estimate density, temperature, and $N$(CO) with a LVG model. This represents 1395 pixels out of $\sim$1.2 million in the mark 1 region. Compared to Pineda et al. (2010) results, and assuming a $T_\textrm{kin}$ of 30 K, we find a higher volume density of molecular hydrogen of 3.3$\rm \times\ 10^3$ $\textrm{cm}^{-3}$, compared to their 250--700 $\textrm{cm}^{-3}$ and a CO column density of 5.7$\rm \times\ 10^{15}\ \textrm{cm}^{-2}$, about a quarter of their value. The differences are important and show the necessity to observe several CO transitions to better describe the intermediate region between the dense cloud and the diffuse atomic medium. Future observations to extend the $^{12}$CO $J=3\rightarrow2$ mapping further away from the $^{13}$CO--detected region comprising mask 1 are needed to revisit our understanding of the diffuse portions of dark clouds.

Structural Analysis of Open Cluster Bochum 2

Authors: Harmeen Kaur, Saurabh Sharma, Alok Durgapal, Lokesh K Dewangan, Aayushi Verma, Neelam Panwar, Rakesh Pandey, Arpan Ghosh
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.01212
Pdf link: https://arxiv.org/pdf/2305.01212
Abstract
We present the results from our deep optical photometric observations of Bochum 2 (Boc2) star cluster obtained using the $1.3$m Devasthal Fast Optical Telescope along with archival photometric data from Pan-STARRS2/2MASS/UKIDSS surveys. We also used high-quality parallax and proper motion data from the $Gaia$ Data Release 3. We found that the Boc2 cluster has a small size ($\sim$1.1 pc) and circular morphology. Using $Gaia$ parallax of member stars and isochrone fitting method, the distance of this cluster is estimated as $3.8\pm0.4$ kpc. We have found that this cluster holds young ($\sim5$ Myr) and massive (O$7-$O$9$) stars as well as an older population of low mass stars. We found that the massive stars have formed in the inner region of the Boc2 cluster in a recent epoch of star formation. We have derived mass function slope ($\Gamma$) in the cluster region as $-2.42\pm0.13$ in the mass range $\sim0.72<$M/M$_{\odot}<2.8$. The tidal radius of the Boc2 cluster ($\sim7-9$) is much more than its observed radius ($\sim1.1$ pc). This suggests that most of the low-mass stars in this cluster are the remains of an older population of stars formed via an earlier epoch of star formation.

Interior-atmosphere modelling to assess the observability of rocky planets with JWST

Authors: Lorena Acuna, Magali Deleuil, Olivier Mousis
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.01250
Pdf link: https://arxiv.org/pdf/2305.01250
Abstract
Super-Earths present compositions dominated by refractory materials. However, there is a degeneracy in their interior structure between a planet with no atmosphere and a small Fe content, and a planet with a thin atmosphere and a higher core mass fraction. To break this degeneracy, atmospheric characterization observations are required. We present a self-consistent interior-atmosphere model to constrain the volatile mass fraction, surface pressure, and temperature of rocky planets with water and CO2 atmospheres. These parameters obtained in our analysis can then be used to predict observations in emission spectroscopy and photometry with JWST, which can determine the presence of an atmosphere, and if present, its composition. To obtain the bolometric emission and Bond albedo for an atmosphere in radiative-convective equilibrium, we present the k-uncorrelated approximation for fast computations within our retrieval on planetary mass, radius and host stellar abundances. For the generation of emission spectra, we use our k-correlated atmospheric model. An adaptive MCMC is used for an efficient sampling of the parameter space at low volatile mass fractions. We show how to use our modelling approach to predict observations with JWST for TRAPPIST-1 c and 55 Cancri e. TRAPPIST-1 c's most likely scenario is a bare surface, although the presence of an atmosphere cannot be ruled out. If the emission in the MIRI F1500 filter is 731 ppm or higher, there would be a water-rich atmosphere. For fluxes between 730 and 400 ppm, no atmosphere is present, while low emission fluxes (300 ppm) indicate a CO2-dominated atmosphere. In the case of 55 Cancri e, a combined spectrum with NIRCam and MIRI LRS may present high uncertainties at wavelengths between 3 and 3.7 $\mu$m. However, this does not affect the identification of H2O and CO2 because they do not present spectral features in this wavelength range.

Impact of astrophysical effects on the dark matter mass constraint with 21cm intensity mapping

Authors: Koya Murakami, Atsushi J. Nishizawa, Kentaro Nagamine, Ikko Shimizu
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.01256
Pdf link: https://arxiv.org/pdf/2305.01256
Abstract
We present an innovative approach to constraining the non-cold dark matter model using a convolutional neural network (CNN). We perform a suite of hydrodynamic simulations with varying dark matter particle masses and generate mock 21cm radio intensity maps to trace the dark matter distribution. Our proposed method complements the traditional power spectrum analysis. We compare our CNN classification results with those from the power spectrum of the differential brightness temperature map of 21cm radiation, and find that the CNN outperforms the latter. Moreover, we investigate the impact of baryonic physics on the dark matter model constraint, including star formation, self-shielding of HI gas, and UV background model. We find that these effects may introduce some contamination in the dark matter constraint, but they are insignificant when compared to the realistic system noise of the SKA instruments.

Coma environment of comet C/2017 K2 around the water ice sublimation boundary observed with VLT/MUSE

Authors: Yuna G. Kwon, Cyrielle Opitom, Manuela Lippi
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.01385
Pdf link: https://arxiv.org/pdf/2305.01385
Abstract
We report a new imaging spectroscopic observation of Oort-cloud comet C/2017 K2 (hereafter K2) on its way to perihelion at 2.53 au, around a heliocentric distance where H2O ice begins to play a key role in comet activation. Normalized reflectances over 6 500--8 500 AA for its inner and outer comae are 9.7+/-0.5 and 7.2+/-0.3 % (10^3 AA)^-1, respectively, the latter being consistent with the slope observed when the comet was beyond the orbit of Saturn. The dust coma at the time of observation appears to contain three distinct populations: mm-sized chunks prevailing at <~10^3 km; a 10^5-km steady-state dust envelope; and fresh anti-sunward jet particles. the dust chunks dominate the continuum signal and are distributed over a similar radial distance scale as the coma region with redder dust than nearby. they also appear to be co-spatial with OI1D, suggesting that the chunks may accommodate H2O ice with a fraction (>~1 %) of refractory materials. The jet particles do not colocate with any gas species detected. The outer coma spectrum contains three significant emissions from C2(0,0) Swan band, OI1D, and CN(1,0 red band, with an overall deficiency in NH2. Assuming that all OI1D flux results from H2O dissociation, we compute an upper limit on the water production rate Q_H2O of ~7 x 10^28 molec s^-1 (with an uncertainty of a factor of two). the production ratio log[Q_C2/Q_CN] of K2 suggests that the comet has typical carbon-chain composition, with the value potentially changing with distance from the Sun. Our observations suggest that water ice-containing dust chunks (>0.1 mm) near K2's nucleus emitted beyond 4 au may be responsible for its very low gas rotational temperature and the discrepancy between its optical and infrared lights reported at similar heliocentric distances.

Massive pre-main-sequence stars in M17: $1^{\rm st}$ and $2^{\rm nd}$ overtone CO bandhead emission and the thermal infrared

Authors: J. Poorta, M.C. Ramírez-Tannus, A. de Koter, F. Backs, A. Derkink, A. Bik, L. Kaper
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.01436
Pdf link: https://arxiv.org/pdf/2305.01436
Abstract
Recently much progress has been made in probing the embedded stages of massive star formation, pointing to formation scenarios akin to a scaled up version of low-mass star formation. However, the latest stages of massive star formation have rarely been observed. Using 1st and 2nd overtone CO bandhead emission and near- to mid-infrared photometry we aim to characterize the remnant formation disks around 5 unique pre-main-sequence (PMS) stars with masses $6-12~\rm M_{\odot}$, that have constrained stellar parameters thanks to their detectable photospheres. We seek to understand this emission and the disks it originates from in the context of the evolutionary stage of the studied sources. We use an analytic LTE disk model to fit the CO bandhead and the dust emission, found to originate in different disk regions. For the first time we modeled the 2nd overtone emission. Furthermore, we fit continuum normalized bandheads and show the importance of this in constraining the emission region. We also include $^{13}\rm CO$ in our models as an additional probe of the young nature of the studied objects. We find that the CO emission originates in a narrow region close to the star (<1 AU) and under very similar disk conditions (temperatures and densities) for the different objects. This is consistent with previous modeling of this emission in a diverse range of young stellar objects. We discuss these results in the context of the positions of these PMS stars in the Hertzsprung-Russel diagram and the CO emission's association with early age and high accretion rates in (massive) young stellar objects. We conclude that, considering their mass range and for the fact that their photospheres are detected, the M17 PMS stars are observed in a relatively early formation stage. They are therefore excellent candidates for longer wavelength studies to further constrain the end stages of massive star formation.

Analytical Fitting of Gamma-ray Photopeaks in Germanium Cross Strip Detectors

Authors: Steven E. Boggs, Sean N. Pike
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Nuclear Experiment (nucl-ex)
Arxiv link: https://arxiv.org/abs/2305.01544
Pdf link: https://arxiv.org/pdf/2305.01544
Abstract
In an ideal germanium detector, fully-absorbed monoenergetic gamma-rays will appear in the measured spectrum as a narrow peak, broadened into a Gaussian of width determined only by the statistical properties of charge cloud generation and the electronic noise of the readout electronics. Multielectrode detectors complicate this picture. Broadening of the charge clouds as they drift through the detector will lead to charge sharing between neighboring electrodes and, inevitably, low-energy tails on the photopeak spectra. We simulate charge sharing in our germanium cross strip detectors in order to reproduce the low-energy tails due to charge sharing. Our goal is to utilize these simulated spectra to develop an analytical fit (shape function) for the spectral lines that provides a robust and high-quality fit to the spectral profile, reliably reproduces the interaction energy, noise width, and the number of counts in both the true photopeak and the low-energy tail, and minimizes the number of additional parameters. Accurate modeling of the detailed line profiles is crucial for both calibration of the detectors as well as scientific interpretation of measured spectra.

Interpretable Machine Learning for Science with PySR and SymbolicRegression.jl

Authors: Miles Cranmer (Princeton University and Flatiron Institute)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); Neural and Evolutionary Computing (cs.NE); Symbolic Computation (cs.SC); Data Analysis, Statistics and Probability (physics.data-an)
Arxiv link: https://arxiv.org/abs/2305.01582
Pdf link: https://arxiv.org/pdf/2305.01582
Abstract
PySR is an open-source library for practical symbolic regression, a type of machine learning which aims to discover human-interpretable symbolic models. PySR was developed to democratize and popularize symbolic regression for the sciences, and is built on a high-performance distributed back-end, a flexible search algorithm, and interfaces with several deep learning packages. PySR's internal search algorithm is a multi-population evolutionary algorithm, which consists of a unique evolve-simplify-optimize loop, designed for optimization of unknown scalar constants in newly-discovered empirical expressions. PySR's backend is the extremely optimized Julia library SymbolicRegression.jl, which can be used directly from Julia. It is capable of fusing user-defined operators into SIMD kernels at runtime, performing automatic differentiation, and distributing populations of expressions to thousands of cores across a cluster. In describing this software, we also introduce a new benchmark, "EmpiricalBench," to quantify the applicability of symbolic regression algorithms in science. This benchmark measures recovery of historical empirical equations from original and synthetic datasets.

Theoretical tidal evolution constants for stellar models from the pre-main sequence to the white dwarf stage Apsidal motion constants, moment of inertia, and gravitational potential energy

Authors: A. Claret
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.01627
Pdf link: https://arxiv.org/pdf/2305.01627
Abstract
One of the most reliable means of studying the stellar interior is through the apsidal motion in double line eclipsing binary systems since these systems present errors in masses, radii, and effective temperatures of only a few per cent. On the other hand, the theoretical values of the apsidal motion to be compared with the observed values depend on the stellar masses of the components and more strongly on their radii (fifth power).The main objective of this work is to make available grids of evolutionary stellar models that, in addition to the traditional parameters (e.g. age, mass, log g, T${\rm eff}$), also contain the necessary parameters for the theoretical study of apsidal motion and tidal evolution. This information is useful for the study of the apsidal motion in eclipsing binaries and their tidal evolution, and can also be used for the same purpose in exoplanetary systems. All models were computed using the MESA package. We consider core overshooting for models with masses $\ge$ 1.2 M$\odot$. For the amount of core overshooting we adopted a recent relationship for mass $\times$ core overshooting. We adopted for the mixing-length parameter $\alpha_{\rm MLT}$ the value 1.84 (the solar-calibrated value). Mass loss was taken into account in two evolutionary phases. The models were followed from the pre-main sequence phase to the white dwarf (WD) stage.The evolutionary models containing age,luminosity, log g, and Teff, as well as the first three harmonics of the internal stellar structure (k$_2$, k$_3$, and k$_4$), the radius of gyration $\beta$ y, and the dimensionless variable $\alpha$, related to gravitational potential energy, are presented in 69 tables covering three chemical compositions: [Fe/H] = -0.50, 0.00, and 0.50. Additional models with different input physics are available.

New submissions for Fri, 26 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 12papers

Effects of Ozone Levels on Climate Through Earth History

Authors: Russell Deitrick, Colin Goldblatt
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Arxiv link: https://arxiv.org/abs/2305.15477
Pdf link: https://arxiv.org/pdf/2305.15477
Abstract
Molecular oxygen in our atmosphere has increased from less than a part per million in the Archean Eon, to a fraction of a percent in the Proterozoic, and finally to modern levels during the Phanerozoic. The ozone layer formed with the early Proterozoic oxygenation. While oxygen itself has only minor radiative and climatic effects, the accompanying ozone has important consequences for Earth climate. Using the Community Earth System Model (CESM), a 3-D general circulation model, we test the effects of various levels of ozone on Earth's climate. When CO2 is held constant, the global mean surface temperature decreases with decreasing ozone, with a maximum drop of ~3.5 K at near total ozone removal. By supplementing our GCM results with 1-D radiative flux calculations, we are able to test which changes to the atmosphere are responsible for this temperature change. We find that the surface temperature change is caused mostly by the stratosphere being much colder when ozone is absent; this makes it drier, substantially weakening the greenhouse effect. We also examine the effect of the structure of the upper troposphere and lower stratosphere on the formation of clouds, and on the global circulation. At low ozone, both high and low clouds become more abundant, due to changes in the tropospheric stability. These generate opposing short-wave and long-wave radiative forcings that are nearly equal. The Hadley circulation and tropospheric jet streams are strengthened, while the stratospheric polar jets are weakened, the latter being a direct consequence of the change in stratospheric temperatures. This work identifies the major climatic impacts of ozone, an important piece of the evolution of Earth's atmosphere.

Exploring the centre of mass properties of LG-like galaxies

Authors: Jean-Baptiste Salomon, Noam Libeskind, Yehuda Hoffman
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.15478
Pdf link: https://arxiv.org/pdf/2305.15478
Abstract
From high resolution cosmological simulations of the Local Group in realistic environment, namely HESTIA simulations, we study the position and kinematic deviations that may arise between the disc of a Milky Way (or Andromeda)-like galaxy and its halo. We focus on the 3-dimensional analysis of the centres of mass (COM). The study presents two parts. We first consider individual particles to track down the very nature and amplitude of the physical deviations of the COM with respect to the distance from the disc centre. Dark matter dominates the behaviour of the COM of all particles at all distances. But the total COM is also very close to the COM of stars. In the absence of a significant merger, the velocity offsets are marginal (10 km/s) but the positional shifts can be important compared to the disc characteristics (>10 kpc). In the event of a massive accretion, discrepancies are of the same order as the recent finding for the MW under the Magellanic Clouds influence. In a second part, the accent is put on the study of various populations of subhaloes and satellites. We show that satellites properly represent the entire subhalo population. There exists strong mismatch in phase space between the satellites' COM and the host disc. Moreover, the results are highly inhomogeneous between the simulations, and thus between the accretion histories. Finally, we point out that these shifts are mainly due to a few of the most massive objects.

Disentangling Stellar Age Estimates from Galactic Chemodynamical Evolution

Authors: Jeff Shen, Joshua S. Speagle, J. Ted Mackereth, Yuan-Sen Ting, Jo Bovy
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.15634
Pdf link: https://arxiv.org/pdf/2305.15634
Abstract
Stellar ages are key for determining the formation history of the Milky Way, but are difficult to measure precisely. Furthermore, methods that use chemical abundances to infer ages may entangle the intrinsic evolution of stars with the chemodynamical evolution of the Galaxy. In this paper, we present a framework for making probabilistic predictions of stellar ages, and then quantify the contribution of both stellar evolution and Galactic chemical evolution to those predictions using SHAP values. We apply this interpretable prediction framework to both a simulated Milky Way sample containing stars in a variety of evolutionary stages and an APOGEE-mocked sample of red clump stars. We find that in the former case, stellar evolution is the dominant driver for age estimates, while in the latter case, the more restricted evolutionary information causes the model to proxy ages through the chemical evolution model. We show that as a result of the use of non-intrinsic Galactic chemical information, trends estimated with the predicted ages, such as the age-metallicity relation, can deviate from the truth.

Resolving the Binary Components of the Outbursting Protostar HBC 494 with ALMA

Authors: Pedro Henrique Nogueira, Alice Zurlo, Sebastián Pérez, Camilo González-Ruilova, Lucas A. Cieza, Antonio Hales, Trisha Bhowmik, Dary A. Ruíz-Rodríguez, David A. Principe, Gregory J. Herczeg, Jonathan P. Williams, Jorge Cuadra, Matías Montesinos, Nicolás Cuello, Prachi Chavan, Simon Casassus, Zhaohuan Zhu, Felipe G. Goicovic
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.15647
Pdf link: https://arxiv.org/pdf/2305.15647
Abstract
Episodic accretion is a low-mass pre-main sequence phenomenon characterized by sudden outbursts of enhanced accretion. These objects are classified into two: protostars with elevated levels of accretion that lasts for decades or more, called FUors, and protostars with shorter and repetitive bursts, called EXors. HBC 494 is a FUor object embedded in the Orion Molecular Cloud. Earlier Atacama Large (sub-)Millimeter Array (ALMA) continuum observations showed an asymmetry in the disk at 0.''2 resolution. Here, we present follow-up observations at ~0.''03, resolving the system into two components: HBC 494 N (primary) and HBC 494 S (secondary). No circumbinary disk was detected. Both disks are resolved with a projected separation of ~0.''18 (75 au). Their projected dimensions are 84+/-1.8 x 66.9+/-1.5 mas for HBC 494 N and 64.6+/-2.5 x 46.0+/-1.9 mas for HBC 494 S. The disks are almost aligned and with similar inclinations. The observations show that the primary is ~5 times brighter/more massive and ~2 times bigger than the secondary. We notice that the northern component has a similar mass to the FUors, while the southern has to EXors. The HBC 494 disks show individual sizes that are smaller than single eruptive YSOs. In this work, we also report 12CO, 13CO, and C18O molecular line observations. At large scale, the 12CO emission shows bipolar outflows, while the 13CO and C18O maps show a rotating and infalling envelope around the system. At a smaller scale, the 12CO and 13CO moment zero maps show cavities within the continuum disks' area, which may indicate continuum over-subtraction or slow-moving jets and chemical destruction along the line-of-sight.

Star-forming environments in smoothed particle magnetohydrodynamics simulations I: Clump extraction and properties

Authors: James Wurster, Connar Rowan
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.15923
Pdf link: https://arxiv.org/pdf/2305.15923
Abstract
What is the nature of a star forming clump? Observations reveal these to be chaotic environments being modified and influenced by many physical processes. However, numerical simulations often define these initial star forming clumps to be idealised objects. In this paper, we define and analyse 109 star forming clumps extracted from our previous low-mass star cluster simulations. To define a clump, we identify all the gas in a simulation that ever becomes bound to or accreted onto a star, then follow the gas backwards in time until it decreases to a critical density. This gas, and its neighbouring gas, is defined as our star forming clump. Our clumps span a mass range of $0.15 \lesssim M/$M$_\odot \lesssim 10.2$, while the density range within each clump spans 2--4 orders of magnitude. The gas density distribution is not smooth, indicating that it is highly structured. The clumps are turbulent, with no coherent rotation. Independent of the initial magnetic field strength of the parent cloud, all clumps yield a similar range of field strengths. The clump magnetic field is ordered, but not reflective of the initial field geometry of the parent cloud. In general, most clump properties have a slight trend with clump mass but are independent of (or only very weakly dependent on) the properties of the parent cloud. We conclude that stars are born from a wide variety of environments and there is not a single universal star forming clump.

Solution To The Cosmic Rays Puzzle ?

Authors: Shlomo Dado, Arnon Dar
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.16003
Pdf link: https://arxiv.org/pdf/2305.16003
Abstract
Recent observations provide compelling evidence that the bulk of the high energy cosmic rays (CRs) and gamma-ray bursts (GRBs) are co-produced by highly relativistic jets of plasmoids of stellar matter. These jets are launched by fall back matter on newly born neutron stars and stellar black holes in core collapse of stripped envelope massive stars with or without an associated supernova. The electrons in the plasmoids produce GRB pulses mainly by inverse Compton scattering of photons on their path, while magnetic reflection of the charged particles produces the high energy cosmic rays.

Formation of complex organic molecules on interstellar CO ices? Insights from computational chemistry simulations

Authors: Stefano Ferrero, Cecilia Ceccarelli, Piero Ugliengo, Mariona Sodupe, Albert Rimola
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Arxiv link: https://arxiv.org/abs/2305.16116
Pdf link: https://arxiv.org/pdf/2305.16116
Abstract
Carbon ($^3$P) atom is a reactive species that, according to laboratory experiments and theoretical calculations, condensates with interstellar ice components. This fact is of uttermost importance for the chemistry in the interstellar medium (ISM) because the condensation reaction is barrierless and the subsequent species formed are still reactive given their open-shell character. Carbon condensation on CO-rich ices forms the \ch{C=C=O} ($^3$$\Sigma$$^-$) species, which can be easily hydrogenated twice to form ketene (H$_2$CCO). Ketene is very reactive in terrestrial conditions, usually found as an intermediate hard to be isolated in chemical synthesis laboratories. These characteristics suggest that ketene can be a good candidate to form interstellar complex organic molecules (iCOMs) via a two-step process, i.e., its activation followed by a radical-radical coupling. In this work, reactions between ketene and atomic H, and the OH and NH$_2$ radicals on a CO-rich ice model have been explored by means of quantum chemical calculations complemented by kinetic calculations to evaluate if they are favourable in the ISM. Results indicate that H addition to ketene (helped by tunneling) to form the acetyl radical (CH$_3$CO) is the most preferred path, as the reactions with OH and NH$_2$ possess activation energies ($\geq$ 9kJ/mol) hard to surmount in the ISM conditions, unless external processes provide energy to the system. Thus, acetaldehyde (CH$_3$CHO) and, probably, ethanol (CH$_3$CH$_2$OH) formation via further hydrogenations are the possible unique operating synthetic routes. Moreover, from the computed relatively large binding energies of OH and NH$_2$ on CO ice, slow diffusion is expected, hampering possible radical-radical couplings with CH$_3$CO. The astrophysical implications of these findings are discussed considering the incoming James Webb Space Telescope observations.

An Optically Targeted Search for Gravitational Waves emitted by Core-Collapse Supernovae during the Third Observing Run of Advanced LIGO and Advanced Virgo

Authors: Marek J. Szczepańczyk, Yanyan Zheng, Javier M. Antelis, Michael Benjamin, Marie-Anne Bizouard, Alejandro Casallas-Lagos, Pablo Cerdá-Durán, Derek Davis, Dorota Gondek-Rosińska, Sergey Klimenko, Claudia Moreno, Martin Obergaulinger, Jade Powell, Dymetris Ramirez, Brad Ratto, Colter Richarson, Abhinav Rijal, Amber L. Stuver, Paweł Szewczyk, Gabriele Vedovato, Michele Zanolin, Imre Bartos, Shubhagata Bhaumik, Tomasz Bulik, Marco Drago, José A. Font, Fabio De Colle, Juan García-Bellido, V. Gayathri, Brennan Hughey, Guenakh Mitselmakher, Tanmaya Mishra, Soma Mukherjee, Quynh Lan Nguyen, Man Leong Chan, Irene Di Palma, Brandon J. Piotrzkowski, Neha Singh
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2305.16146
Pdf link: https://arxiv.org/pdf/2305.16146
Abstract
We present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed optically within 30 Mpc during the third observing run of Advanced LIGO and Advanced Virgo. No gravitational wave associated with a core-collapse supernova has been identified. We then report the detection efficiency for a variety of possible gravitational-wave emissions. For neutrino-driven explosions, the distance at which we reach 50% detection efficiency is up to 8.9 kpc, while more energetic magnetorotationally-driven explosions are detectable at larger distances. The distance reaches for selected models of the black hole formation, and quantum chromodynamics phase transition are also provided. We then constrain the core-collapse supernova engine across a wide frequency range from 50 Hz to 2 kHz. The upper limits on gravitational-wave energy and luminosity emission are at low frequencies down to $10^{-4},M_\odot c^2$ and $5 \times 10^{-4},M_\odot c^2$/s, respectively. The upper limits on the proto-neutron star ellipticity are down to 5 at high frequencies. Finally, by combining the results obtained with the data from the first and second observing runs of LIGO and Virgo, we improve the constraints of the parameter spaces of the extreme emission models. Specifically, the proto-neutron star ellipticities for the long-lasting bar mode model are down to 1 for long emission (1 s) at high frequency.

A Parametric Model for Self-Interacting Dark Matter Halos

Authors: Daneng Yang, Ethan O. Nadler, Hai-Bo Yu, Yi-Ming Zhong
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2305.16176
Pdf link: https://arxiv.org/pdf/2305.16176
Abstract
We propose a parametric model for studying self-interacting dark matter (SIDM) halos. The model uses an analytical density profile, calibrated using a controlled N-body SIDM simulation that covers the entire gravothermal evolution, including core-forming and -collapsing phases. By normalizing the calibrated density profile, we obtain a universal description for SIDM halos at any evolution phase. The model allows us to infer properties of SIDM halos based on their cold dark matter (CDM) counterparts. As a basic application, we only require two characteristic parameters of an isolated CDM halo at $z=0$. We then extend the model to incorporate effects induced by halo mass changes, such as major mergers or tidal stripping, making it applicable to both isolated halos and subhalos. The parametric model is tested and validated using cosmological zoom-in SIDM simulations available in the literature.

Transiting Exoplanet Yields for the Roman Galactic Bulge Time Domain Survey Predicted from Pixel-Level Simulations

Authors: Robert F. Wilson, Thomas Barclay, Brian P. Powell, Joshua Schlieder, Christina Hedges, Benjamin T. Montet, Elisa Quintana, Iain McDonald, Matthew T. Penny, Nestor Espinoza, Eamonn Kerins
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.16204
Pdf link: https://arxiv.org/pdf/2305.16204
Abstract
The Nancy Grace Roman Space Telescope (Roman) is NASA's next astrophysics flagship mission, expected to launch in late 2026. As one of Roman's core community science surveys, the Galactic Bulge Time Domain Survey (GBTDS) will collect photometric and astrometric data for over 100 million stars in the Galactic bulge to search for microlensing planets. To assess the potential with which Roman can detect exoplanets via transit, we developed and conducted pixel-level simulations of transiting planets in the GBTDS. From these simulations, we predict that Roman will find between $\sim$60,000 and $\sim$200,000 transiting planets, over an order of magnitude more planets than are currently known. While the majority of these planets will be giants ($R_p>4R_\oplus$) on close-in orbits ($a<0.3$ au), the yield also includes between $\sim$7,000 and $\sim$12,000 small planets ($R_p<4 R_\oplus$). The yield for small planets depends sensitively on the observing cadence and season duration, with variations on the order of $\sim$10-20% for modest changes in either parameter, but is generally insensitive to the trade between surveyed area and cadence given constant slew/settle times. These predictions depend sensitively on the Milky Way's metallicity distribution function, highlighting an incredible opportunity to understand exoplanet demographics across a comprehensive set of stellar populations and Galactic environments.

Spectroscopic survey of faint planetary-nebula nuclei. II. The subdwarf O central star of Fr 2-30

Authors: Howard E. Bond (1,2), Klaus Werner (3), Gregory R. Zeimann (4), Jonathan Talbot (5) ((1) Penn State Univ., (2) Space Telescope Science Institute, (3) IAAT, Tuebingen, Germany, (4) McDonald Observatory, (5) Stark Bayou Observatory)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.16247
Pdf link: https://arxiv.org/pdf/2305.16247
Abstract
Fr 2-30 = PN? G126.8-15.5 is a faint emission nebula, hosting a 14th-mag central star that we identify here for the first time. Deep Halpha and [O III] images reveal a roughly elliptical nebula with dimensions of at least 22'x14', fading into a surrounding network of even fainter emission. Optical spectrograms of the central star show it to have a subdwarf O spectral type, with a Gaia parallax distance of 890 pc. A model-atmosphere analysis gives parameters of Teff = 60,000 K, log g = 6.0, and a low helium content of nHe/nH = 0.0017. The location of the central star in the log g -- Teff plane is inconsistent with a post-asymptotic-giant-branch evolutionary status. Two alternatives are that it is a helium-burning post-extreme-horizontal-branch object, or a hydrogen-burning post-red-giant-branch star. In either case the evolutionary ages are so long that a detectable planetary nebula (PN) should not be present. We find evidence for a variable radial velocity (RV), suggesting that the star is a close binary. However, there are no photometric variations, and the spectral-energy distribution rules out a companion earlier than M2 V. The RVs of the star and surrounding nebula are discordant, and the nebula lacks typical PN morphology. We suggest that Fr 2-30 is a "PN mimic" -- the result of a chance encounter between the hot sdO star and an interstellar cloud. However, we note the puzzling fact that there are several nuclei of genuine PNe that are known to be in evolutionary states similar to that of the Fr 2-30 central star.

A New Forced Photometry Service for the Zwicky Transient Facility

Authors: Frank J. Masci, Russ R. Laher, Benjamin Rusholme, David Shupe, Roberta Paladini, Steve Groom, Avery Wold
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.16279
Pdf link: https://arxiv.org/pdf/2305.16279
Abstract
We describe the Zwicky Transient Facility (ZTF) Forced Photometry Service (ZFPS) as developed and maintained by the ZTF Science Data System Team at IPAC/Caltech. The service is open for public use following a subscription. The ZFPS has been operational since early 2020 and has been used to generate publication quality lightcurves for a myriad of science programs. The ZFPS has been recently upgraded to allow users to request forced-photometry lightcurves for up to 1500 sky positions per request in a single web-application submission. The underlying software has been recoded to take advantage of a parallel processing architecture with the most compute-intensive component rewritten in C and optimized for the available hardware. The ZTF processing cluster consists of 66 compute nodes, each hosting at least 16 physical cores. The compute nodes are generally idle following nightly real-time processing of the ZTF survey data and when other ad hoc processing tasks have been completed. The ZFPS and associated infrastructure at IPAC/Caltech therefore enable thousands of forced-photometry lightcurves to be generated along with a wealth of quality metrics to facilitate analyses and filtering of bad quality data prior to scientific use.

by olozhika (Xing Yuchen).

2023-05-26

New submissions for Wed, 10 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-10

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 11papers

Binary neutron star populations in the Milky Way

Authors: Cecilia Sgalletta, Giuliano Iorio, Michela Mapelli, M. Celeste Artale, Lumen Boco, Debatri Chattopadhyay, Andrea Lapi, Andrea Possenti, Stefano Rinaldi, Mario Spera
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04955
Pdf link: https://arxiv.org/pdf/2305.04955
Abstract
Galactic binary neutron stars (BNSs) are a unique laboratory to probe the evolution of BNSs and their progenitors. Here, we use a new version of the population synthesis code SEVN to evolve the population of Galactic BNSs, by modeling the spin up and down of pulsars self-consistently. We analyze the merger rate $\mathcal{R}{\rm MW}$, orbital period $P{\rm orb}$, eccentricity $e$, spin period $P$, and spin period derivative $\dot{P}$ of the BNS population. Values of the common envelope parameter $\alpha=1 - 3$ and an accurate model of the Milky Way star formation history best reproduce the BNS merger rate in our Galaxy ($\mathcal{R}{\rm MW}\approx{}30$ Myr$^{-1}$). We apply radio-selection effects to our simulated BNSs and compare them to the observed population. Using a Dirichlet process Gaussian mixture method, we evaluate the four-dimensional likelihood in the $(P{\rm orb}, e, P, \dot{P})$ space, by comparing our radio-selected simulated pulsars against Galactic BNSs. Our analysis favours an uniform initial distribution for both the magnetic field ($10^{10-13}$ G) and the spin period ($10-100$ ms). The implementation of radio selection effects is critical to match not only the spin period and period derivative, but also the orbital period and eccentricity of Galactic BNSs. According to our fiducial model, the Square Kilometre Array will detect $\sim 20$ new BNSs in the Milky Way.

The impact and response of minihalos and the inter-halo medium on cosmic reionization

Authors: Tsang Keung Chan, Alejandro Benitez-Llambay, Tom Theuns, Carlos Frenk, Richard Bower
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.04959
Pdf link: https://arxiv.org/pdf/2305.04959
Abstract
An ionization front (I-front) that propagates through an inhomogeneous medium is slowed down by self-shielding and recombinations. We perform cosmological radiation hydrodynamics simulations of the I-front propagation during the epoch of cosmic reionization. The simulations resolve gas in minihalos (halo mass $10^4\lesssim M_h[{\rm M}\odot]\lesssim 10^8)$ that could dominate recombinations, in a computational volume that is large enough to sample the abundance of such halos. The numerical resolution is sufficient (gas particle mass $\sim 20{\rm M}\odot$, spatial resolution $< 0.1;{\rm ckpc}$) to allow accurate modelling of the hydrodynamic response of gas to photo-heating. We quantify the photo-evaporation time of minihalos as a function of $M_h$ and its dependence on the photo-ionization rate, $\Gamma_{-12}$, and the redshift of reionization, $z_i$. The recombination rate can be enhanced over that of a uniform medium by a factor $\sim 10-20$ early on. The peak value increases with $\Gamma_{-12}$ and decreases with $z_i$, due to the enhanced contribution from minihalos. The clumping factor, $c_r$, decreases to a factor of a few at $\sim 100;{\rm Myr}$ after the passage of the I-front when the minihalos have been photo-evaporated; this asymptotic value depends only weakly on $\Gamma_{-12}$. Recombinations increase the required number of photons per baryon to reionize the Universe by 20-100 per cent, with the higher value occurring when $\Gamma_{-12}$ is high and $z_i$ is low. We complement the numerical simulations with simple analytical models for the evaporation rate and the inverse Str"omgren layer. The study also demonstrates the proficiency and potential of SPHM1RT to address astrophysical problems in high-resolution cosmological simulations.

Implementation of chemistry in the Athena++ code

Authors: Munan Gong, Ka-Wai Ho, James M. Stone, Eve C. Ostriker, Paola Caselli, Tommaso Grassi, Chang-Goo Kim, Jeong-Gyu Kim, Goni Halevi
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.04965
Pdf link: https://arxiv.org/pdf/2305.04965
Abstract
Chemistry plays a key role in many aspects of astrophysical fluids. Atoms and molecules are agents for heating and cooling, determine the ionization fraction, serve as observational tracers, and build the molecular foundation of life. We present the implementation of a chemistry module in the publicly available magneto-hydrodynamic code Athena++. We implement several chemical networks and heating and cooling processes suitable for simulating the interstellar medium (ISM). A general chemical network framework in the KIDA format is also included, allowing the user to easily implement their own chemistry. Radiation transfer and cosmic-ray ionization are coupled with chemistry and solved with the simple six-ray approximation. The chemical and thermal processes are evolved as a system of coupled ODEs with an implicit solver from the CVODE library. We perform and present a series of tests to ensure the numerical accuracy and convergence of the code. Many tests combine chemistry with gas dynamics, including comparisons with analytic solutions, 1D problems of the photo-dissociation regions and shocks, and realistic 3D simulations of the turbulent ISM. We release the code with the new public version of Athena++, aiming to provide a robust and flexible code for the astrochemical simulation community.

A Low-Mass Helium Star Progenitor Model for the Type Ibn SN 2020nxt

Authors: Qinan Wang, Anika Goel, Luc Dessart, Ori D. Fox, Melissa Shahbandeh, Sofia Rest, Armin Rest, Jose H. Groh, Andrew Allan, Claes Fransson, Nathan Smith, Griffin Hosseinzadeh, Alexei V. Filippenko, Jennifer Andrews, K. Azalee Bostroem, Thomas G. Brink, Peter Brown, Jamison Burke, Roger Chevalier, Geoffrey C. Clayton, Mi Dai, Kyle W. Davis, Ryan J. Foley, Sebastian Gomez, Chelsea Harris, Daichi Hiramatsu, D. Andrew Howell, Connor Jennings, Saurabh W. Jha, Mansi M. Kasliwal, Patrick L. Kelly, Erik C. Kool, Evelyn Liu, Emily Ma, Curtis McCully, Adam M. Miller, Yukei Murakami, Craig Pellegrino, Estefania Padilla Gonzalez, Derek Perera, Justin Pierel, César Rojas-Bravo, Matthew R. Siebert, Jesper Sollerman, Tamás Szalai, Samaporn Tinyanont, Schuyler D. Van Dyk, WeiKang Zheng, Kenneth C. Chambers, et al. (9 additional authors not shown)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.05015
Pdf link: https://arxiv.org/pdf/2305.05015
Abstract
A growing number of supernovae (SNe) are now known to exhibit evidence for significant interaction with a dense, pre-existing, circumstellar medium (CSM). SNe Ibn comprise one such class that can be characterised by both rapidly evolving light curves and persistent narrow He I lines. The origin of such a dense CSM in these systems remains a pressing question, specifically concerning the progenitor system and mass-loss mechanism. In this paper, we present multi-wavelength data of the Type Ibn SN 2020nxt, including $HST$/STIS ultraviolet spectra. We fit the data with recently updated CMFGEN models designed to handle configurations for SNe Ibn. The UV coverage yields strong constraints on the energetics and, when combined with the CMFGEN models, offer new insight on potential progenitor systems. We find the most successful model is a $\lesssim4 {\rm M}\odot$ helium star that lost its $\sim 1,{\rm M}\odot$ He-rich envelope in the years preceding core collapse. We also consider viable alternatives, such as a He white dwarf merger. Ultimately, we conclude at least some SNe Ibn do not arise from single, massive ($>30 {\rm M}_\odot$) Wolf-Rayet-like stars.

An analysis of the isomers HCN and HNC in the evolution of high-mass star-forming regions

Authors: N.C. Martinez, S. Paron
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.05073
Pdf link: https://arxiv.org/pdf/2305.05073
Abstract
The study of molecules and their chemistry in star-forming regions is fundamental to understand the physical process occurring in such regions. The HCN and HNC J=1-0 emissions were used to derive their integrated line intensities (I), to probe a relation recently appeared in the literature between the kinetic temperatures (T${K}$) and the isomeric (I) ratio, and to obtain the isomers abundances (X) in 55 high-mass star-forming regions. These last ones are classified, according to the evolutive stage, as infrared dark clouds, high-mass protostellar objects, hot molecular cores, and ultracompact HII regions. It is inferred that the T${K}$ obtained from the isomeric integrated intensity ratio (I$^{HCN/HNC}$) are underestimated, and hence we suggest that this relation cannot be employed as an universal thermometer in the interstellar medium. The isomers abundances show a behavior that can be explained from the chemistry occurring as the temperature and the UV radiation increase according to the evolutive stage. We found that the abundance ratio (X$^{HCN/HNC}$) hardly could be used as a chemical clock, and we suggest that it can be approximated by I$^{HCN/HNC}$. This work is part of an on-going study of multiple molecules that stand in the sample of analyzed regions which intends to contribute in the chemical knowledge of high-mass star formation.

AREPO White Dwarf merger simulations resulting in edge-lit detonation and run-away hypervelocity companion

Authors: Uri Pierre Burmester, Lilia Ferrario, Rüdiger Pakmor, Ivo R. Seitenzahl, Ashley J. Ruiter, Matthew Hole
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.05192
Pdf link: https://arxiv.org/pdf/2305.05192
Abstract
We present a series of high-resolution simulations generated with the moving-mesh code AREPO to model the merger of a $1.1 , \mathrm{M_\odot}$ carbon-oxygen primary white dwarf with an outer helium layer and a $0.35,\mathrm{M_\odot}$ secondary helium white dwarf. Our simulations lead to detonations that are consistent with the edge-lit scenario, where a helium detonation is ignited at the base of the helium layer of the primary WD, which triggers an off-centre carbon detonation. This produces an asymmetric ejecta pattern and differences in line-of-sight observables (e.g. mean atomic weight). The ejecta that are flung into space are dominated by $^{56}\mathrm{Ni}$, $^{4}\mathrm{He}$, $^{28}\mathrm{Si}$, and $^{32}\mathrm{S}$. Our simulations result in a surviving degenerate companion of mass $0.22-0.25$ $\mathrm{M_\odot}$ moving at $>1,700$ $\mathrm{km},\mathrm{s}^{-1}$, consistent with the observational findings of hypervelocity WDs. The secondary's surface layers are enriched by heavy metals, with $^{56}\mathrm{Ni}$ making up approximately $0.8 %$ of the remaining mass. We also analyse the sensitivity of the outcome on simulation parameters, including the "inspiral time", which defines a period of accelerated angular momentum loss. We find that the choice of "inspiral time" qualitatively influences the simulation result, including the survival of the secondary. We argue that the shorter inspiral cases result in qualitatively and quantitatively similar outcomes. We also investigate the sensitivity of our results on the primary's chemical profile by comparing simulations using isothermal, constant composition models with the same mass and central composition and characterised by either a bare carbon-oxygen core (no helium) or a carbon-oxygen core enveloped by a thick helium layer.

EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf

Authors: J. Krticka, A. Kawka, Z. Mikulasek, L. Fossati, I. Krtickova, M. Prvak, J. Janik, R. Liptaj, M. Zejda, E. Paunzen
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.05270
Pdf link: https://arxiv.org/pdf/2305.05270
Abstract
Very precise satellite photometry has revealed a large number of variable stars whose variability is caused either by surface spots or by binarity. Detailed studies of such variables provide insights into the physics of these objects. We study the nature of the periodic light variability of the white dwarf EPIC 206197016 that was observed by the K2 mission. We obtain phase-resolved medium-resolution spectroscopy of EPIC 206197016 using XSHOOTER spectrograph at VLT to understand the nature of the white dwarf variability. We use NLTE model atmospheres to determine stellar parameters at individual phases. EPIC 206197016 is a hot DA white dwarf with $T_\text{eff}=78,$kK. The analysis of the spectra reveals periodic radial velocity variations that can result from gravitational interaction with an invisible secondary whose mass corresponds to a red dwarf. The close proximity of the two stars where the semimajor axis is about $3,R_\odot$ results in the irradiation of the companion with temperatures more than twice as high on the illuminated side compared to the nonilluminated hemisphere. This effect can explain the observed light variations. The spectra of the white dwarf show a particular feature of the Balmer lines called the Balmer line problem, where the observed cores of the lower Balmer lines are deeper than predicted. This can be attributed to either weak pollution of hydrogen in the white dwarf atmosphere by heavy elements or to the presence of a circumstellar cloud or disk.

Low-Temperature Kinetics for the N + NO reaction: Experiment Guides the Way

Authors: Kevin M. Hickson, Juan Carlos San Vicente Veliz, Debasish Koner, Markus Meuwly
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Arxiv link: https://arxiv.org/abs/2305.05305
Pdf link: https://arxiv.org/pdf/2305.05305
Abstract
The reaction N(4S) + NO -> O(3P) + N2 plays a pivotal role in the conversion of atomic to molecular nitrogen in dense interstellar clouds and in the atmosphere. Here we report a joint experimental and computational investigation of the N + NO reaction with the aim of providing improved constraints on its low temperature reactivity. Thermal rates were measured over the 50 to 296 K range in a continuous supersonic flow reactor coupled with pulsed laser photolysis and laser induced fluorescence for the production and detection of N(4S) atoms, respectively. With decreasing temperature, the experimentally measured reaction rate was found to monotonously increase up to a value of (6.6 +- 1.3) x 10-11 cm3 s-1 at 50 K. To confirm this finding, quasi-classical trajectory simulations were carried out on a previously validated, full-dimensional potential energy surface (PES). However, around 50 K the computed rates decreased which required re-evaluation of the reactive PES in the long-range part due to a small spurious barrier with height 40 K in the entrance channel. By exploring different correction schemes the measured thermal rates can be adequately reproduced, displaying a clear negative temperature dependence over the entire temperature range. The possible astrochemical implications of an increased reaction rate at low temperature are also discussed.

Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A

Authors: Zhen Cao, F. Aharonian, Q. An, Axikegu, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, J.T. Cai, Q. Cao, W.Y. Cao, Zhe Cao, J. Chang, J.F. Chang, A.M. Chen, E.S. Chen, Liang Chen, Lin Chen, Long Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, M.Y. Cui, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, Danzengluobu, D. della Volpe, X.Q. Dong, K.K. Duan, J.H. Fan, Y.Z. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, X.T. Feng, Y.L. Feng, S. Gabici, B. Gao, C.D. Gao, L.Q. Gao, Q. Gao, W. Gao, W.K. Gao, M.M. Ge, L.S. Geng, G. Giacinti, G.H. Gong, Q.B. Gou, M.H. Gu, F.L. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.Y. He, X.B. He, Y. He, M. Heller, Y.K. Hor, B.W. Hou, C. Hou, X. Hou, H.B. Hu, Q. Hu, et al. (201 additional authors not shown)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.05372
Pdf link: https://arxiv.org/pdf/2305.05372
Abstract
The diffuse Galactic $\gamma$-ray emission, mainly produced via interactions between cosmic rays and the diffuse interstellar medium, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $\gamma$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner ($15^{\circ}<l<125^{\circ}$, $|b|<5^{\circ}$) and outer ($125^{\circ}<l<235^{\circ}$, $|b|<5^{\circ}$) Galactic plane are detected with $29.1\sigma$ and $12.7\sigma$ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain ($E>10$~TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of $-2.99\pm0.04$, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of $\sim3$ than the prediction. A similar spectrum with an index of $-2.99\pm0.07$ is found in the outer Galaxy region, and the absolute flux for $10\lesssim E\lesssim60$ TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show slight deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

Understanding Sun-as-a-star variability of solar Balmer lines

Authors: Serena Criscuoli, Sergey Marchenko, Matthew DeLand, Debi Choudhary, Greg Kopp
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.05510
Pdf link: https://arxiv.org/pdf/2305.05510
Abstract
Precise, high-cadence, long-term records of stellar spectral variability at different temporal scales lead to better understanding of a wide variety of phenomena including stellar atmospheres and dynamos, convective motions, and rotational periods. Here, we investigate the variability of solar Balmer lines (H-$\alpha$, -$\beta$, -$\gamma$, -$\delta$) observed by space-borne radiometers (OSIRIS, SCIAMACHY, OMI, and GOME-2), combining these precise, long-term observations with high-resolution data from the ground-based NSO/ISS spectrograph. We relate the detected variability to the appearance of magnetic features on the solar disk. We find that on solar-rotational timescales (about 1 month), the Balmer line activity indices (defined as line-core to line-wing ratios) closely follow variations in the total solar irradiance (which is predominantly photospheric), thus frequently (specifically, during passages of sunspot groups) deviating from behavior of activity indices that track chromospheric activity levels. On longer timescales, the correlation with chromospheric indices increases, with periods of low- or even anti-correlation found at intermediate timescales. Comparison of these observations with estimates from semi-empirical irradiance reconstructions helps quantify the contributions of different magnetic and quiet features. We conclude that both the lower sensitivity to network and in part the higher sensitivity to filaments and prominences, may result in complex, time-dependent relationships between Balmer and other chromospheric indices observed for the Sun and solar-like stars. The fact that core and wings contribute in similar manner to the variability, and current knowledge of Balmer-lines formation in stellar atmospheres, support the notion that Balmer lines core-to-wing ratios indices behave more like photospheric rather than chromospheric indices.

Identification of interstellar cyanamide towards the hot molecular core G358.93-0.03 MM1

Authors: Arijit Mannna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA); Chemical Physics (physics.chem-ph)
Arxiv link: https://arxiv.org/abs/2305.05578
Pdf link: https://arxiv.org/pdf/2305.05578
Abstract
The amide-related molecules are essential for the formation of the other complex bio-molecules and an understanding of the prebiotic chemistry in the interstellar medium (ISM). We presented the first detection of the rotational emission lines of the amide-like molecule cyanamide (NH${2}$CN) towards the hot molecular core G358.93$-$0.03 MM1 using the Atacama Large Millimeter/Submillimeter Array (ALMA). Using the rotational diagram model, the derived column density of NH${2}$CN towards the G358.93$-$0.03 MM1 was (5.9$\pm$2.5)$\times$10$^{14}$ cm$^{-2}$ with a rotational temperature of 100.6$\pm$30.4 K. The derived fractional abundance of NH${2}$CN towards the G358.93$-$0.03 MM1 with respect to H${2}$ was (4.72$\pm$2.0)$\times$10$^{-10}$, which is very similar to the existent three-phase warm-up chemical model abundances of NH${2}$CN. We compare the estimated abundance of NH${2}$CN towards G358.93$-$0.03 MM1 with other sources, and we observe the abundance of NH${2}$CN towards G358.93$-$0.03 MM1 is nearly similar to that of the sculptor galaxy NGC 253 and the low-mass protostars IRAS 16293-2422 B and NGC 1333 IRAS4A2. We also discussed the possible formation mechanisms of NH${2}$CN towards the hot molecular cores and hot corinos, and we find that the NH${2}$CN molecule was created in the grain-surfaces of G358.93-0.03 MM1 via the neutral-neutral reaction between NH${2}$ and CN.

New submissions for Tue, 13 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 9papers

The Disturbed and Globular Cluster-Rich Ultra-diffuse Galaxy UGC 9050-Dw1

Authors: Catherine E. Fielder, Michael G. Jones, David J. Sand, Paul Bennet, Denija Crnojevic, Ananthan Karunakaran, Burcin Mutlu-Pakdil, Kristine Spekkens
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.06164
Pdf link: https://arxiv.org/pdf/2306.06164
Abstract
We investigate the ultra-diffuse galaxy (UDG) UGC 9050-Dw1, which was selected because of its disturbed morphology as part of a larger sample of UDGs that display evidence for significant interactions. We use the Hubble Space Telescope's Advanced Camera for Surveys to identify globular clusters (GCs) associated with UGC 9050-Dw1, and the Jansky Very Large Array to measure its $\mathrm{H}\mathrm{I}$ content. UGC 9050-Dw1, a neighbor to the low surface brightness spiral UGC 9050, exhibits a unique UV bright central ``clump'' with clearly associated $\mathrm{H}{\mathrm{I}}$ gas and an extended stellar tidal plume to the north. We identify $52^{+4}{-6}$ GCs, implying a specific frequency $S\mathrm{N} = 122_{-24}^{+30}$, one of the highest reported for a UDG of this luminosity. Additionally, $\sim 20%$ of the total light of the galaxy is contributed by GCs. Nearly uniform GC colors suggest they were formed during a single intense episode of star formation. We propose that UGC 9050-Dw1 formed via a rare dwarf merger event where induced, clumpy star formation led to its current observed properties.

Revealing the Chemical Structure of the Magellanic Clouds with APOGEE. I. Calculating Individual Stellar Ages of RGB Stars in the Large Magellanic Cloud

Authors: Joshua T. Povick, David L. Nidever, Pol Massana, Jamie Tayar, Knut A.G. Olsen, Sten Hasselquist, Maria-Rosa L. Cioni, Christian Nitschelm, Ricardo Carrera, Yumi Choi, Alexandre Roman-Lopes, Steven R. Majewski, Andrés Almeida, Katia Cunha, Verne V. Smith
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.06348
Pdf link: https://arxiv.org/pdf/2306.06348
Abstract
Stellar ages are critical for understanding the temporal evolution of a galaxy. We calculate the ages of over 6000 red giant branch stars in the Large Magellanic Cloud (LMC) observed with SDSS-IV / APOGEE-S. Ages are derived using multi-band photometry, spectroscopic parameters (T$_\text{eff}$, $\log{g}$, [Fe/H], and [$\alpha$/Fe]) and stellar isochrones and the assumption that the stars lie in a thin inclined plane to get accurate distances. The isochrone age and extinction are varied until a best match is found for the observed photometry. We perform validation using the APOKASC sample, which has asteroseismic masses and accurate ages, and find that our uncertainties are $\sim$20% and range from $\sim$1$-$3 Gyr for the calculated age values. Here we present the LMC age map as well as the age-radius relation and an accurate age-metallicity relation (AMR). The age map and age-radius relation reveal that recent star formation in the galaxy was more centrally located and that there is a slight dichotomy between the north and south with the northern fields being slightly younger. The northern fields that cover a known spiral arm have median ages of $\gtrsim$ 2 Gyr, which is the time when an interaction with the SMC is suggested to have happened. The AMR is mostly flat especially for older ages although recently (about 2.0-2.5 Gyr ago) there is an increase in the median [Fe/H]. Based on the time frame, this might also be attributed to the close interaction between the LMC and SMC.

A tera-electronvolt afterglow from a narrow jet in an extremely bright gamma-ray burst 221009A

Authors: LHAASO Collaboration
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.06372
Pdf link: https://arxiv.org/pdf/2306.06372
Abstract
Some gamma-ray bursts (GRBs) have an afterglow in the tera-electronvolt (TeV) band, but the early onset of this afterglow has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons (above 0.2~TeV) were detected within the first 3000 seconds. The TeV photon flux began several minutes after the GRB trigger, then rose to a flux peak about 10 seconds later. This was followed by a decay phase, which became more rapid at $\sim 650,{\rm s}$ after the peak. The emission can be explained with a relativistic jet model with half-opening angle $\sim 0.8^\circ$, consistent with the core of a structured jet. This interpretation could explain the high isotropic energy of this GRB.

Shear, writhe and filaments: turbulence in the high latitude molecular cloud MBM 40

Authors: Marco Monaci, Loris Magnani, Steven N. Shore, Henrik Olofsson, Mackenzie R. Joy
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.06670
Pdf link: https://arxiv.org/pdf/2306.06670
Abstract
Context. It is almost banal to say that the interstellar medium (ISM) is structurally and thermodynamically complex. But the variety of the governing processes, including stellar feedback, renders the investigation challenging. High latitude molecular clouds (HLMCs) with no evidence of internal star formation, such as MBM 40, are excellent sites for studying the chemistry and dynamic evolution of the cold neutral ISM. Aims. We used this high latitude cloud as an exemplar for the dynamical and chemical processes in the diffuse interstellar medium. Methods. We analyzed new and archival $^{12}$CO, $^{13}$CO, CH, HCO$^+$, CS, H$_2$CO, HCN data from Five College Radio Observatory (FCRAO), Onsala Space Observatory (OSO), Arizona Radio Observatory (ARO) and W. Gordon telescope (Arecibo) combined with the Galactic Arecibo L-band Feed Array HI (GALFA-HI) HI 21 cm data set, to study the chemistry, thermal state, and dynamics of MBM 40. A new dynamical analytical approach was adopted by considering each line profile as a line of sight Probability Distribution Function (PDF) of the turbulence weighted by gas emissivity. Results. The atomic and molecular gas are smoothly distributed in space and velocity. No steep transition is seen between circumcloud atomic and cloud molecular gas in either radial velocity or structure. We proposed a topology of the cloud from the molecular tracers, a contorted filamentary structure that is shaped by a broad embedding shear flow in the neutral atomic gas. Comparative examination of different molecular tracers shows that $^{13}$CO, H$_2$CO and CS arise from only denser molecular cores, where $^{12}$CO, CH and HCO$^+$ traces diffuse gas with broader range of dynamics.

Aerosol parameters for night sky brightness modelling estimated from daytime sky images

Authors: Miroslav Kocifaj, František Kundracik, John Barentine
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.06750
Pdf link: https://arxiv.org/pdf/2306.06750
Abstract
Atmospheric turbidity is one of the key factors influencing the propagation of artificial light into the environment during cloudless nights. High aerosol loading can reduce the visibility of astronomical objects, and thus information on atmospheric pollution is critical for the prediction of the night sky brightness (NSB) distribution. In particular, the aerosol optical depth (AOD) and asymmetry parameter (g) are among the most important aerosol properties influencing the NSB amplitudes. However, these two parameters are rarely available at astronomical sites. Here, we develop a method for AOD and g retrievals from clear-sky radiometry carried out around sunset or sunrise, shortly before or after night-time observation is intended. The method allows for reducing the number of unknowns needed in the processing and interpretation of night sky radiances, and thus provides an efficient tool for gathering input data to present skyglow simulators. The practice of collecting information about aerosols in this way could become a routine part of astronomical observations, much like observing standard stars to obtain extinction coefficients. If the procedure were conducted around sunset and the data were quickly reduced, it could offer an on-the-spot estimate of the NSB for the night ahead. The error analysis is performed using the theoretical model, while taking into account experimental errors of radiance readings. The capability of the method is demonstrated in a field experiment conducted under cloudless conditions.

On the origin of the anomalous gas, non-declining rotation curve and disc asymmetries in NGC253

Authors: Xuanyi Lyu, T. Westmeier, Gerhardt R. Meurer, D. J. Hanish
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.06869
Pdf link: https://arxiv.org/pdf/2306.06869
Abstract
We present a multi-wavelength (from far ultraviolet to HI emission) study of star formation feedback on the kinematics of the interstellar medium in the Sculptor Galaxy, NGC253. Its three well-known features (a disrupted stellar disc, a previously reported delining rotation curve, and anomalous HI gas) are studied in a common context of disc asymmetries. About 170 h of on-source ATCA observations are collected and reduced into two versions of \HI\ data cubes of different angular resolution (30'' / 2') and HI column density sensitivity (7.4 $\times$ $10^{19}$cm$^{-2}$ / 4$\times$ $10^{18}$cm$^{-2}$). We separate the anomalous gas from the disc using a custom-made line profile fitting toolkit called FMG. Two star formation tracers (H$\alpha$, FUV emission) are carefully processed and studied. We find that at $R > 7.5~\mathrm{kpc}$ the star formation activity is strongly lopsided (SFR${NE}$ >SFR${SW}$), and investigate several other properties (H$\alpha$/FUV, dust temperature, stellar age, and disc stability parameters). We also find that the declining nature of the rotation curve perceived by previous studies is not intrinsic but a combined effect of kinematical asymmetries at $R = 7.5$--$16~\mathrm{kpc}$. This is likely the consequence of star formation triggered outflow. The mass distribution and the timescale of the anomalous gas also imply that it originates from gas outflow, which is perhaps caused by galaxy-galaxy interaction considering the crowded environment of NGC253.

A CO Funnel in the Galactic Centre: Molecular Counterpart of the Northern Galactic Chimney?

Authors: V. S. Veena, D. Riquelme, W.-J. Kim, K. M. Menten, P. Schilke, M. C. Sormani, W. E. Banda-Barragan, F. Wyrowski, G. A. Fuller, A. Cheema
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.06980
Pdf link: https://arxiv.org/pdf/2306.06980
Abstract
We report the discovery of a velocity coherent, funnel shaped ^13CO emission feature in the Galactic centre (GC) using data from the SEDIGISM survey. The molecular cloud appears as a low velocity structure (V_LSR=[-3.5, +3.5] km/s) with an angular extent of 0.95{\deg} x 1{\deg}, extending toward positive Galactic latitudes. The structure is offset from Sgr A* toward negative Galactic longitudes and spatially and morphologically correlates well with the northern lobe of the 430 pc radio bubble, believed to be the radio counterpart of the multiwavelength GC chimney. Spectral line observations in the frequency range of 85-116 GHz have been carried out using the IRAM 30 metre telescope toward 12 positions along the funnel-shaped emission. We examine the ^12C/^13C isotopic ratios using various molecules and their isotopologues. The mean ^12C/^13C isotope ratio (30.6+-2.9) is consistent with the structure located within inner 3 kpc of the Galaxy and possibly in the GC. The velocity of the molecular funnel is consistent with previous radio recombination line measurements of the northern lobe of radio bubble. Our multiwavelength analysis suggests that the funnel shaped structure extending over 100 pc above the Galactic plane is the molecular counterpart of the northern GC chimney.

On the occurrence of stellar fission in binary-driven hypernovae

Authors: S. R. Zhang, R. Ruffini
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.07097
Pdf link: https://arxiv.org/pdf/2306.07097
Abstract
The binary-driven hypernova (BdHN) model address long gamma-ray bursts (GRBs) associated with type Ic supernovae (SNe) through a series of physical episodes that occur in a binary composed of a carbon-oxygen (CO) star (of mass about 10 solar mass) and a neutron star (NS) companion (of mass about 2 solar mass) in a compact orbit. The SN explosion of the CO star triggers sequence of seven events. The BdHN model has followed the traditional picture of the SN from the CO iron's core collapse. However, the lack of a solution to the problem of producing successful SNe leaves room for alternative scenarios. We here show that tidal synchronization of the CO-NS binary can lead the CO star to critical conditions for fission, hence splitting into two stellar remnants, e.g., about 8.5 solar mass + 1.5 solar mass. We give specific examples of the properties of the products for various orbital periods relevant to BdHNe. The astrophysical consequences of this scenario are outlined.

Searching for Radio Outflows from M31* with VLBI Observations

Authors: Sijia Peng, Zhiyuan Li, Lorant O. Sjouwerman, Yang Yang, Wu Jiang, Zhi-qiang Shen
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.07189
Pdf link: https://arxiv.org/pdf/2306.07189
Abstract
As one of the nearest and most dormant supermassive black holes (SMBHs), M31* provides a rare but promising opportunity for studying the physics of black hole accretion and feedback at the quiescent state. Previous Karl G. Jansky Very Large Array (VLA) observations with an arcsec resolution have detected M31* as a compact radio source over centimeter wavelengths, but the steep radio spectrum suggests optically-thin synchrotron radiation from an outflow driven by a hot accretion flow onto the SMBH. Aiming to probe the putative radio outflow, we have conducted milli-arcsec-resolution very long baseline interferometric (VLBI) observations of M31* in 2016, primarily at 5 GHz and combining the Very Long Baseline Array, Tianma-65m and Shanghai-25m Radio Telescopes. Despite the unprecedented simultaneous resolution and sensitivity achieved, no significant ($\gtrsim 3\sigma$) signal is detected at the putative position of M31* given an RMS level of $\rm 5.9~\mu Jy\ beam^{-1}$, thus ruling out a point-like source with a peak flux density comparable to that ($\sim30~\mu Jy\ beam^{-1}$) measured by the VLA observations taken in 2012. We disfavor the possibility that M31* has substantially faded since 2012, in view that a 2017 VLA observation successfully detected M31* at a historically-high peak flux density ($\sim75~\mu Jy\ beam^{-1}$ at 6 GHz). Instead, the non-detection of the VLBI observations is best interpreted as the arcsec-scale core being resolved out at the milli-arcsec-scale, suggesting an intrinsic size of M31* at 5 GHz larger than $\sim300$ times the Schwarzschild radius. Such extended radio emission may originate from a hot wind driven by the weakly accreting SMBH.

by olozhika (Xing Yuchen).

2023-06-13

New submissions for Tue, 2 May 23

Update Star Formation & Molecular Cloud papers at 2am UTC (10am Beijing time) every weekday, forked from zhuhu00/Paper-Daily-Notice.
2023-05-02

Keyword list: ['star formation', 'molecular cloud', 'N-PDF', 'cloud', 'interstellar medium', 'core', 'filament', 'atomic gas']

Recent Progress in Modelling the Macro- and Micro-Physics of Radio Jet Feedback in Galaxy Clusters

Authors: Martin A. Bourne, Hsiang-Yi Karen Yang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00019
Pdf link: https://arxiv.org/pdf/2305.00019
Abstract
Radio jets and the lobes they inflate are common in cool-core clusters and are expected to play a critical role in regulating the heating and cooling of the intracluster medium (ICM). This is an inherently multi-scale problem, and much effort has been made to understand the processes governing the inflation of lobes and their impact on the cluster, as well as the impact of the environment on the jet-ICM interaction, on both macro- and microphysical scales. Developments of new numerical techniques and improving computational resources have seen simulations of jet feedback in galaxy clusters become ever more sophisticated. This ranges from modelling ICM plasma physics processes such as the effects of magnetic fields, cosmic rays and viscosity to including jet feedback in cosmologically evolved cluster environments in which the ICM thermal and dynamic properties are shaped by large-scale structure formation. In this review, we discuss the progress made over the last ~decade in capturing both the macro- and microphysical processes in numerical simulations, highlighting both the current state of the field as well as open questions and potential ways in which these questions can be addressed in the future.

Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution -- Insights from the IRAM NOEMA large program CORE

Authors: Aida Ahmadi, H. Beuther, F. Bosco, C. Gieser, S. Suri, J. C. Mottram, R. Kuiper, Th. Henning, Á. Sánchez-Monge, H. Linz, R. E. Pudritz, D. Semenov, J. M. Winters, T. Möller, M. T. Beltrán, T. Csengeri, R. Galván-Madrid, K. G. Johnston, E. Keto, P. D. Klaassen, S. Leurini, S. N. Longmore, S. L. Lumsden, L. T. Maud, L. Moscadelli, A. Palau, T. Peters, S. E. Ragan, J. S. Urquhart, Q. Zhang, H. Zinnecker
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.00020
Pdf link: https://arxiv.org/pdf/2305.00020
Abstract
The fragmentation mode of high-mass molecular clumps and the accretion processes that form the most massive stars ($M\gtrsim 8M_\odot$) are still not well understood. To this end, we have undertaken a large observational program (CORE) making use of interferometric observations from the Northern Extended Millimetre Array (NOEMA) for a sample of 20 luminous ($L>10^4L_\odot$) protostellar objects in the 1.37 mm wavelength regime in both continuum and line emission, reaching $\sim$0.4" resolution (800 au at 2 kpc). Using the dense gas tracer CH$3$CN, we find velocity gradients across 13 cores perpendicular to the directions of bipolar molecular outflows, making them excellent disk candidates. Specific angular momentum ($j$) radial profiles are on average $\sim10^{-3}$ km /s pc and follow $j \propto r^{1.7}$, consistent with a poorly resolved rotating and infalling envelope/disk model. Fitting the velocity profiles with a Keplerian model, we find protostellar masses in the range of $\sim 10-25$ $M\odot$. Modelling the level population of CH$_3$CN lines, we present temperature maps and find median gas temperatures in the range $70-210$ K. We create Toomre $Q$ maps to study the stability of the disks and find almost all (11 of 13) disk candidates to be prone to fragmentation due to gravitational instabilities at the scales probed by our observations. In particular, disks with masses greater than $\sim10-20%$ of the mass of their host (proto)stars are Toomre unstable, and more luminous protostellar objects tend to have disks that are more massive and hence more prone to fragmentation. Our finings show that most disks around high-mass protostars are prone to disk fragmentation early in their formation due to their high disk to stellar mass ratio. This impacts the accretion evolution of high-mass protostars which will have significant implications for the formation of the most massive stars.

Machine Learning Uncovers the Universe's Hidden Gems: A Comprehensive Catalogue of CIV Absorption Lines in SDSS DR12

Authors: Reza Monadi, Ming-Feng Ho, Kathy L. Cooksey, Simeon Bird
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00023
Pdf link: https://arxiv.org/pdf/2305.00023
Abstract
We assemble the largest CIV absorption line catalogue to date, leveraging machine learning, specifically Gaussian processes, to remove the need for visual inspection for detecting CIV absorbers. The catalogue contains probabilities classifying the reliability of the absorption system within a quasar spectrum. Our training set was a sub-sample of DR7 spectra that had no detectable CIV absorption in a large visually inspected catalogue. We used Bayesian model selection to decide between our continuum model and our absorption-line models. Using a random hold-out sample of 1301 spectra from all of the 26,030 investigated spectra in DR7 CIV catalogue, we validated our pipeline and obtained an 87% classification performance score. We found good purity and completeness values, both ~80%, when a probability of ~95% is used as the threshold. Our pipeline obtained similar CIV redshifts and rest equivalent widths to our training set. Applying our algorithm to 185,425 selected quasar spectra from SDSS DR12, we produce a catalogue of 113,775 CIV doublets with at least 95% confidence. Our catalogue provides maximum a posteriori values and credible intervals for CIV redshift, column density, and Doppler velocity dispersion. We detect CIV absorption systems with a redshift range of 1.37 $!-!$ 5.1, including 33 systems with a redshift larger than 5 and 549 absorbers systems with a rest equivalent width greater than 2 A at more than 95% confidence. Our catalogue can be used to investigate the physical properties of the circumgalactic and intergalactic media.

Detection of monothioformic acid towards the solar-type protostar IRAS 16293-2422

Authors: Arijit Manna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00480
Pdf link: https://arxiv.org/pdf/2305.00480
Abstract
In the interstellar medium (ISM), the complex organic molecules that contain the thiol group ($-$SH) play an important role in the polymerization of amino acids. We look for SH-bearing molecules in the chemically rich solar-type protostar IRAS 16293-2422. After the extensive spectral analysis using the local thermodynamic equilibrium (LTE) model, we have detected the rotational emission lines of trans-isomer monothioformic acid (t-HC(O)SH) towards the IRAS 16293 B using the Atacama Large Millimeter/Submillimeter Array (ALMA). We did not observe any evidence of cis-isomer monothioformic acid (c-HC(O)SH) towards the IRAS 16293 B. The column density of t-HC(O)SH towards the IRAS 16293 B was (1.02$\pm$0.6)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 125$\pm$15 K. The fractional abundance of t-HC(O)SH with respect to H${2}$ towards the IRAS 16293 B is 8.50$\times$10$^{-11}$. The column density ratio of t-HC(O)SH/CH${3}$SH towards the IRAS 16293 B is 0.185. We compare our estimated abundance of t-HC(O)SH towards the IRAS 16293 B with the abundance of t-HC(O)SH towards the galactic center quiescent cloud G+0.693-0.027 and hot molecular core G31.41+0.31. After the comparison, we found that the abundance of t-HC(O)SH towards the IRAS 16293 B is several times of magnitude lower than G+0.693-0.027 and G31.41+0.31. We also discuss the possible formation mechanism of t-HC(O)SH in the ISM.

Joint Modelling of Dust Scattering and Thermal Emission: The Spider Complex

Authors: Jielai Zhang, Peter G Martin, Ryan Cloutier, Natalie Price-Jones, Roberto Abraham, Pieter van Dokkum, Allison Merritt
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.00756
Pdf link: https://arxiv.org/pdf/2305.00756
Abstract
Observations across the electromagnetic spectrum of radiative processes involving interstellar dust -- emission, extinction, and scattering -- are used to constrain the parameters of dust models and more directly to aid in foreground removal of dust for extragalactic and cosmology observations. The more complementary observations, the better. Here, we quantify the relationship between scattered light and thermal emission from dust in a diffuse (cirrus) intermediate latitude cloud, Spider, using data from the Dragonfly Telephoto Array and the Herschel Space Observatory. A challenge for optical observations of faint cirrus is accurate removal of a contaminating spatially varying sky background. We present a technique to analyse two images of the same cirrus field concurrently, correlating pixel values to capture the relationship and simultaneously fitting the sky background as a complex non-correlating additive component. For the Spider, we measure a $g-r$ color of 0.644$\pm 0.024$ and a visible wavelength to 250 $\mu$m intensity ratio of $10^{-3} \times (0.855 \pm0.025)$ and $10^{-3} \times (1.55\pm0.08)$ for $g$ and $r$-band respectively. We show how to use any dust model that matches the thermal dust emission to predict an upper limit to the amount of scattered light. The actual brightness of the cirrus will be fainter than this limit because of anisotropic scattering by the dust combined with anisotropy of the incident interstellar radiation field (ISRF). Using models of dust and the ISRF in the literature we illustrate that the predicted brightness is indeed lower, though not as faint as the observations indicate.

Small Planets Around Cool Dwarfs: Enhanced Formation Efficiency of Super-Earths around M dwarfs

Authors: Yayaati Chachan, Eve J. Lee
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.00803
Pdf link: https://arxiv.org/pdf/2305.00803
Abstract
Current measurements of planet population as a function of stellar mass show three seemingly contradictory signatures: close-in super-Earths are more prevalent around M dwarfs than FGK dwarfs; inner super-Earths are correlated with outer giants; and outer giants are less common around M dwarfs than FGK dwarfs. Here, we build a simple framework that combines the theory of pebble accretion with the measurements of dust masses in protoplanetary disks to reconcile all three observations. First, we show that cooler stars are more efficient at converting pebbles into planetary cores at short orbital periods. Second, when disks are massive enough to nucleate a heavy core at 5 AU, more than enough dust can drift in to assemble inner planets, establishing the correlation between inner planets and outer giants. Finally, while stars of varying masses are similarly capable of converting pebbles into cores at long orbital periods, hotter stars are much more likely to harbor more massive dust disks so that the giant planet occurrence rate rises around hotter stars. Our results are valid over a wide range of parameter space for a disk accretion rate that follows $\dot{M}\star \sim 10^{-8},M\odot,{\rm yr}^{-1}(M_\star/M_\odot)^2$. We predict a decline in mini-Neptune population (but not necessarily terrestrial planets) around stars lighter than $\sim 0.3-0.5 , M_\odot$. Cold giants ($\gtrsim$5 AU), if they exist, should remain correlated with inner planets even around lower mass stars.

New submissions for Thu, 29 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

阅读 Usage.md了解如何使用此repo实现个性化的Arxiv论文推送
See Usage.md for instructions on how to personalize the repo.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 7papers

Discovery of the Magellanic Stellar Stream Out to 100 Kiloparsecs

Authors: Vedant Chandra, Rohan P. Naidu, Charlie Conroy, Ana Bonaca, Dennis Zaritsky, Phillip A. Cargile, Nelson Caldwell, Benjamin D. Johnson, Jiwon Jesse Han, Yuan-Sen Ting
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.15719
Pdf link: https://arxiv.org/pdf/2306.15719
Abstract
The Magellanic Stream (MS) - an enormous ribbon of gas spanning $140^\circ$ of the southern sky trailing the Magellanic Clouds - has been exquisitely mapped in the five decades since its discovery. However, despite concerted efforts, no stellar counterpart to the MS has been conclusively identified. This stellar stream would reveal the distance and 6D kinematics of the MS, constraining its formation and the past orbital history of the Clouds. We have been conducting a spectroscopic survey of the most distant and luminous red giant stars in the Galactic outskirts. From this dataset, we have discovered a prominent population of 13 stars matching the extreme angular momentum of the Clouds, spanning up to $100^\circ$ along the MS at distances of $60-120$ kpc. Furthermore, these kinemetically-selected stars lie along a [$\alpha$/Fe]-deficient track in chemical space from $-2.5 < \mathrm{[Fe/H]} < -0.5$, consistent with their formation in the Clouds themselves. We identify these stars as high-confidence members of the Magellanic Stellar Stream. Half of these stars are metal-rich and closely follow the gaseous MS, whereas the other half are more scattered and metal-poor. We argue that the metal-rich stream is the recently-formed tidal counterpart to the MS, and speculate that the metal-poor population was thrown out of the SMC outskirts during an earlier interaction between the Clouds. The Magellanic Stellar Stream provides a strong set of constraints - distances, 6D kinematics, and birth locations - that will guide future simulations towards unveiling the detailed history of the Clouds.

A close-in giant planet escapes engulfment by its star

Authors: Marc Hon, Daniel Huber, Nicholas Z. Rui, Jim Fuller, Dimitri Veras, James S. Kuszlewicz, Oleg Kochukhov, Amalie Stokholm, Jakob Lysgaard Rørsted, Mutlu Yıldız, Zeynep Çelik Orhan, Sibel Örtel, Chen Jiang, Daniel R. Hey, Howard Isaacson, Jingwen Zhang, Mathieu Vrard, Keivan G. Stassun, Benjamin J. Shappee, Jamie Tayar, Zachary R. Claytor, Corey Beard, Timothy R. Bedding, Casey Brinkman, Tiago L. Campante, William J. Chaplin, Ashley Chontos, Steven Giacalone, Rae Holcomb, Andrew W. Howard, Jack Lubin, Mason MacDougall, Benjamin T. Montet, Joseph M. A. Murphy, Joel Ong, Daria Pidhorodetska, Alex S. Polansk, Malena Rice, Dennis Stello, Dakotah Tyler, Judah Van Zandt, Lauren Weiss
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.15877
Pdf link: https://arxiv.org/pdf/2306.15877
Abstract
When main-sequence stars expand into red giants, they are expected to engulf close-in planets. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars. Here we present the discovery that the giant planet 8 Ursae Minoris b orbits a core-helium-burning red giant. At a distance of only 0.5 au from its host star, the planet would have been engulfed by its host star, which is predicted by standard single-star evolution to have previously expanded to a radius of 0.7 au. Given the brief lifetime of helium-burning giants, the nearly circular orbit of the planet is challenging to reconcile with scenarios in which the planet survives by having a distant orbit initially. Instead, the planet may have avoided engulfment through a stellar merger that either altered the evolution of the host star or produced 8 Ursae Minoris b as a second-generation planet. This system shows that core-helium-burning red giants can harbour close planets and provides evidence for the role of non-canonical stellar evolution in the extended survival of late-stage exoplanetary systems.

Cosmic-ray-driven enhancement of the C$^0$/CO abundance ratio in W51C

Authors: Mitsuyoshi Yamagishi, Kenji Furuya, Hidetoshi Sano, Natsuko Izumi, Tatsuya Takekoshi, Hidehiro Kaneda, Kouichiro Nakanishi, Takashi Shimonishi
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.15983
Pdf link: https://arxiv.org/pdf/2306.15983
Abstract
We examine spatial variations of the C$^0$/CO abundance ratio ($X_{\mathrm{C/CO}}$) in the vicinity of the $\gamma$-ray supernova remnant W51C, based on [CI] ($^3P_1$-$^3P_0$), $^{12}$CO(1-0), and $^{13}$CO(1-0) observations with the ASTE and Nobeyama 45-m telescopes. We find that $X_{\mathrm{C/CO}}$ varies in a range of 0.02-0.16 (0.05 in median) inside the molecular clouds of $A_V>$100 mag, where photodissociation of CO by the interstellar UV is negligible. Furthermore, $X_{\mathrm{C/CO}}$ is locally enhanced up to by a factor of four near the W51C center, depending on the projected distance from the W51C center. In high-$A_V$ molecular clouds, $X_{\mathrm{C/CO}}$ is determined by the ratio of the cosmic-ray (CR) ionization rate to the H$2$ density, and we find no clear spatial variation of the H$2$ density against the projected distance. Hence, the high CR ionization rate may locally enhance $X{\mathrm{C/CO}}$ near the W51C center. We also find that the observed spatial extent of the enhanced $X{\mathrm{C/CO}}$ ($\sim$17 pc) is consistent with the diffusion distance of CRs with the energy of 100 MeV. The fact suggests that the low-energy CRs accelerated in W51C enhance $X_{\mathrm{C/CO}}$. The CR ionization rate at the $X_{\mathrm{C/CO}}$-enhanced cloud is estimated to be 3$\times$10$^{-16}$ s$^{-1}$ on the basis of time-dependent PDR simulations of $X_{\mathrm{C/CO}}$, the value of which is 30 times higher than that in the standard Galactic environment. These results demonstrate that [CI] is a powerful probe to investigate the interaction between CRs and the interstellar medium for a wide area in the vicinity of supernova remnants.

Extreme data compression for Bayesian model comparison

Authors: Alan F. Heavens, Arrykrishna Mootoovaloo, Roberto Trotta, Elena Sellentin
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.15998
Pdf link: https://arxiv.org/pdf/2306.15998
Abstract
We develop extreme data compression for use in Bayesian model comparison via the MOPED algorithm, as well as more general score compression. We find that Bayes factors from data compressed with the MOPED algorithm are identical to those from their uncompressed datasets when the models are linear and the errors Gaussian. In other nonlinear cases, whether nested or not, we find negligible differences in the Bayes factors, and show this explicitly for the Pantheon-SH0ES supernova dataset. We also investigate the sampling properties of the Bayesian Evidence as a frequentist statistic, and find that extreme data compression reduces the sampling variance of the Evidence, but has no impact on the sampling distribution of Bayes factors. Since model comparison can be a very computationally-intensive task, MOPED extreme data compression may present significant advantages in computational time.

Diffuse neutrino background from past core-collapse supernovae

Authors: Shin'ichiro Ando, Nick Ekanger, Shunsaku Horiuchi, Yusuke Koshio
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.16076
Pdf link: https://arxiv.org/pdf/2306.16076
Abstract
Core-collapse supernovae are among the most powerful explosions in the universe, emitting thermal neutrinos that carry away the majority of the gravitational binding energy released. These neutrinos create a diffuse supernova neutrino background (DSNB), one of the largest energy budgets among all radiation backgrounds. Detecting the DSNB is a crucial goal of modern high-energy astrophysics and particle physics, providing valuable insights in both core-collapse modeling, neutrino physics, and cosmic supernova rate history. In this review, we discuss the key ingredients of DSNB calculation and what we can learn from future detections, including black-hole formation and non-standard neutrino interactions. Additionally, we provide an overview of the latest updates in neutrino experiments, which could lead to the detection of the DSNB in the next decade. With the promise of this breakthrough discovery on the horizon, the study of DSNB holds enormous potential for advancing our understanding of the Universe.

Setting an upper limit for the total TeV neutrino flux from the disk of our Galaxy

Authors: Vittoria Vecchiotti, Francesco L. Villante, Giulia Pagliaroli
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.16305
Pdf link: https://arxiv.org/pdf/2306.16305
Abstract
We set an upper limit for the total TeV neutrino flux expected from the disk of our Galaxy in the region $|l|<30^{\circ}$ and $|b|<2^{\circ}$ probed by the ANTARES experiment. We include both the diffuse emission, due to the interaction of cosmic rays with the interstellar medium, and the possible contribution produced by gamma-ray Galactic sources. The neutrino diffuse emission is calculated under different assumptions for the cosmic ray spatial and energy distribution in our Galaxy. In particular, we assume that the total gamma-ray flux produced by all the sources, resolved and unresolved by H.E.S.S., is produced via hadronic interaction and, hence, is coupled with neutrino emission. We compare our total neutrino flux with the recent ANTARES measurement of the neutrino from the Galactic Ridge. We show that the ANTARES best-fit flux requires the existence of a large source component, close to or even larger than the most optimistic predictions obtained with our approach.

Constraining MeV-scale axion-like particles with Fermi-LAT observations of SN 2023ixf

Authors: Eike Müller, Pierluca Carenza, Christopher Eckner, Ariel Goobar
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.16397
Pdf link: https://arxiv.org/pdf/2306.16397
Abstract
The Fermi-LAT observations of SN 2023ixf, a Type II supernova in the nearby Pinwheel Galaxy, Messier 101 (M101), presents us with an excellent opportunity to constrain MeV-scale Axion-Like Particles (ALPs). By examining the photon decay signature from heavy ALPs that could be produced in the explosion, we improve the existing constraints on the ALP-photon coupling by up to a factor of $ \sim 2 $ for masses $ m_a \lesssim 3 $ MeV, with the exact value depending mostly on plasma properties of the collapsing core. This study demonstrates the relevance of core-collapse supernovae, also beyond the Magellanic Clouds, as probes of fundamental physics.

by olozhika (Xing Yuchen).

2023-06-29

New submissions for Tue, 2 May 23

Keyword: star formation

Molecular gas content and high excitation of a massive main-sequence galaxy at z = 3

Authors: Han Lei, Francesco Valentino, Georgios E. Magdis, Vasily Kokorev, Daizhong Liu, Dimitra Rigopoulou, Shuowen Jin, Emanuele Daddi
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00024
Pdf link: https://arxiv.org/pdf/2305.00024
Abstract
We present new CO ($J=5-4$ and $7-6$) and [CI] ($^3P_2,-, ^3P_1$ and $^3P_1,-, ^3P_0$) emission line observations of the star-forming galaxy D49 at the massive end of the Main Sequence at $z=3$. We incorporate previous CO ($J=3-2$) and optical-to-millimetre continuum observations to fit its spectral energy distribution (SED). Our results hint at high-$J$ CO luminosities exceeding the expected location on the empirical correlations with the infrared luminosity. [CI] emission fully consistent with the literature trends is found. We do not retrieve any signatures of a bright active galactic nucleus that could boost the $J=5-4,,7-6$ lines in either the infrared or X-ray bands, but warm photon-dominated regions, shocks or turbulence could in principle do so. We suggest that mechanical heating could be a favourable mechanism able to enhance the gas emission at fixed infrared luminosity in D49 and other main-sequence star-forming galaxies at high redshift, but further investigation is necessary to confirm this explanation. We derive molecular gas masses from dust, CO, and [CI] that all agree within the uncertainties. Given its large star formation rate (SFR) $\sim 500~~M_\odot~~{\rm yr}^{-1}$ and stellar mass $>10^{11.5}~M_\odot$, the short depletion time scale of $<0.3$ Gyr might indicate that D49 is experiencing its last growth spurt and will soon transit to quiescence.

Feedback-driven anisotropy in the circumgalactic medium for quenching galaxies in the SIMBA simulations

Authors: Tianyi Yang, Romeel Davé, Weiguang Cui, Yan-Chuan Cai, John A. Peacock, Daniele Sorini
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.00602
Pdf link: https://arxiv.org/pdf/2305.00602
Abstract
We use the SIMBA galaxy formation simulation suite to explore anisotropies in the properties of circumgalactic gas that result from accretion and feedback processes. We particularly focus on the impact of bipolar active galactic nuclei (AGN) jet feedback as implemented in SIMBA, which quenches galaxies and has a dramatic effect on large-scale gas properties. We show that jet feedback at low redshifts is most common in the stellar mass range $(1-5)\times 10^{10}M_\odot$, so we focus on galaxies with active jets in this mass range. In comparison to runs without jet feedback, jets cause lower densities and higher temperatures along the galaxy minor axis (SIMBA jet direction) at radii >=$0.5r_{200c}-4r_{200c}$ and beyond. This effect is less apparent at higher or lower stellar masses, and is strongest within green valley galaxies. The metallicity also shows strong anisotropy out to large scales, driven by star formation feedback. We find substantially stronger anisotropy at <=$0.5r_{200c}$, but this also exists in runs with no explicit feedback, suggesting that it is due to anisotropic accretion. Finally, we explore anisotropy in the bulk radial motion of the gas, finding that both star formation and AGN wind feedback contribute to pushing the gas outwards along the minor axis at <=1 Mpc, but AGN jet feedback further causes bulk outflow along the minor axis out to several Mpc, which drives quenching via gas starvation. These results provide observational signatures for the operation of AGN feedback in galaxy quenching.

Keyword: molecular cloud

There is no result

Keyword: N-PDF

There is no result

New submissions for Tue, 16 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 10papers

Multi-messenger observations of core-collapse supernovae: Exploiting the standing accretion shock instability

Authors: Marco Drago, Haakon Andresen, Irene Di Palma, Irene Tamborra, Alejandro Torres-Forné
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2305.07688
Pdf link: https://arxiv.org/pdf/2305.07688
Abstract
The gravitational wave (GW) and neutrino signals from core-collapse supernovae (CCSNe) are expected to carry pronounced imprints of the standing accretion shock instability (SASI). We investigate whether the correlation between the SASI signatures in the GW and neutrino signals could be exploited to enhance the detection efficiency of GWs. We rely on a benchmark full-scale three-dimensional CCSN simulation with zero-age main sequence mass of $27\ M_\odot$. Two search strategies are explored: 1.~the inference of the SASI frequency range and/or time window from the neutrino event rate detectable at the IceCube Neutrino Observatory; 2.~the use of the neutrino event rate to build a matched filter template. We find that incorporating information from the SASI modulations of the IceCube neutrino event rate can increase the detection efficiency compared to standard GW excess energy searches up to $30%$ for nearby CCSNe. However, we do not find significant improvements in the overall GW detection efficiency for CCSNe more distant than $1.5$~kpc. We demonstrate that the matched filter approach performs better than the unmodeled search method, which relies on a frequency bandpass inferred from the neutrino signal. The improved detection efficiency provided by our matched filter method calls for additional work to outline the best strategy for the first GW detection from CCSNe.

Compton-thick AGN in the NuSTAR Era X: Analysing seven local CT-AGN candidates

Authors: Dhrubojyoti Sengupta, Stefano Marchesi, Cristian Vignali, Núria Torres-Albà, Elena Bertola, Andrealuna Pizzetti, Giorgio Lanzuisi, Francesco Salvestrini, Xiurui Zhao, Massimo Gaspari, Roberto Gilli, Andrea Comastri, Alberto Traina, Francesco Tombesi, Ross Silver, Francesca Pozzi, Marco Ajello
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.07705
Pdf link: https://arxiv.org/pdf/2305.07705
Abstract
We present the broad-band X-ray spectral analysis (0.6-50 keV) of seven Compton-Thick active galactic nuclei (CT-AGN; line-of-sight, l.o.s., column density $>10^{24}$ cm$^{-2}$) candidates selected from the Swift-BAT 100-month catalog, using archival NuSTAR data. This work is in continuation of the on-going research of the Clemson-INAF group to classify CT-AGN candidates at redshift $z<0.05$, using physically-motivated torus models. Our results confirm that three out of seven targets are \textit{bona-fide} CT-AGN. Adding our results to the previously analysed sources using NuSTAR data, we increase the population of bona-fide CT-AGN by $\sim9%$, bringing the total number to 35 out of 414 AGN. We also performed a comparative study using MyTorus and borus02 on the spectra in our sample, finding that both physical models are strongly consistent in the parameter space of l.o.s. column density and photon index. Furthermore, the clumpiness of the torus clouds is also investigated by separately computing the line-of-sight and average torus column densities, in each of the seven sources. Adding our results to all the previous 48 CT-AGN candidates analysed by the Clemson-INAF research team having NuSTAR observations: we find $78%$ of the sources are likely to have a clumpy distribution of the obscuring material surrounding the accreting supermassive black hole.

Intercomparison of Brown Dwarf Model Grids and Atmospheric Retrieval Using Machine Learning

Authors: Anna Lueber, Daniel Kitzmann, Chloe E. Fisher, Brendan P. Bowler, Adam J. Burgasser, Mark Marley, Kevin Heng
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)
Arxiv link: https://arxiv.org/abs/2305.07719
Pdf link: https://arxiv.org/pdf/2305.07719
Abstract
Understanding differences between sub-stellar spectral data and models has proven to be a major challenge, especially for self-consistent model grids that are necessary for a thorough investigation of brown dwarf atmospheres. Using the supervised machine learning method of the random forest, we study the information content of 14 previously published model grids of brown dwarfs (from 1997 to 2021). The random forest method allows us to analyze the predictive power of these model grids, as well as interpret data within the framework of Approximate Bayesian Computation (ABC). Our curated dataset includes 3 benchmark brown dwarfs (Gl 570D, {\epsilon} Indi Ba and Bb) as well as a sample of 19 L and T dwarfs; this sample was previously analyzed in Lueber et al. (2022) using traditional Bayesian methods (nested sampling). We find that the effective temperature of a brown dwarf can be robustly predicted independent of the model grid chosen for the interpretation. However, inference of the surface gravity is model-dependent. Specifically, the BT-Settl, Sonora Bobcat and Sonora Cholla model grids tend to predict logg ~3-4 (cgs units) even after data blueward of 1.2 {\mu}m have been disregarded to mitigate for our incomplete knowledge of the shapes of alkali lines. Two major, longstanding challenges associated with understanding the influence of clouds in brown dwarf atmospheres remain: our inability to model them from first principles and also to robustly validate these models.

UV signatures of magnetar formation and their crucial role for Gravitational Wave detection

Authors: Sandhya S. Menon, Dafne Guetta, Simone Dall'Osso
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.07761
Pdf link: https://arxiv.org/pdf/2305.07761
Abstract
The emission from shock breakouts (SBOs) represents the earliest electromagnetic (EM) signal emitted by cataclysmic events involving the formation or the merger of neutron stars (NSs). As such, SBOs carry unique information on the structure of their progenitors and on the explosion energy. The characteristic~~SBO emission is expected in the UV range, and its detection is one of the key targets of~~the ULTRASAT satellite. Among SBO sources, we focus on a specific class involving the formation of fast spinning magnetars in the core-collapse (CC) of massive stars. Fast spinning magnetars are expected to produce a specific signature in the early UV supernova light curve, powered by the extra spin energy quickly released by the NS. Moreover, they are considered as optimal candidates for the emission of long-transient gravitational wave (GW) signals, the detection of which requires early EM triggers to boost the sensitivity of dedicated GW search pipelines. We calculate early supernova UV light curves in the presence of a magnetar central engine, as a function of the explosion energy, ejecta mass and magnetar parameters. We then estimate the ULTRASAT detection horizon (z < 0.15) as a function of the same physical parameters, and the overall expected detection rate finding that magnetar-powered SBOs may represent up to 1/5 of the total events detected by ULTRASAT. Moreover, at the expected sensitivity of the LIGO/Virgo/Kagra O5 science run, one such event occurring within 5 Mpc will providean ideal trigger for a GW long transient search. Future GW detectors like the Einstein Telescope will push the horizon for joint EM-GW detections to 35-40 Mpc.

Unveiling the formation of the massive DR21 ridge

Authors: L. Bonne, S. Bontemps, N. Schneider, R. Simon, S. D. Clarke, T. Csengeri, E. Chambers, U. Graf, J. M. Jackson, R. Klein, Y. Okada, A. G. G. M. Tielens, M. Tiwari
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.07785
Pdf link: https://arxiv.org/pdf/2305.07785
Abstract
We present new $^{13}$CO(1-0), C$^{18}$O(1-0), HCO$^{+}$(1-0) and H$^{13}$CO$^{+}$(1-0) maps from the IRAM 30m telescope, and a spectrally-resolved [CII] 158 $\mu$m map observed with the SOFIA telescope towards the massive DR21 cloud. This traces the kinematics from low- to high-density gas in the cloud which allows to constrain the formation scenario of the high-mass star forming DR21 ridge. The molecular line data reveals that the sub-filaments are systematically redshifted relative to the dense ridge. We demonstrate that [CII] unveils the surrounding CO-poor gas of the dense filaments in the DR21 cloud. We also show that this surrounding gas is organized in a flattened cloud with curved redshifted dynamics perpendicular to the ridge. The sub-filaments thus form in this curved and flattened mass reservoir. A virial analysis of the different lines indicates that self-gravity should drive the evolution of the ridge and surrounding cloud. Combining all results we propose that bending of the magnetic field, due to the interaction with a mostly atomic colliding cloud, explains the velocity field and resulting mass accretion on the ridge. This is remarkably similar to what was found for at least two nearby low-mass filaments. We tentatively propose that this scenario might be a widespread mechanism to initiate star formation in the Milky Way. However, in contrast to low-mass clouds, gravitational collapse plays a role on the pc scale of the DR21 ridge because of the higher density. This allows more effective mass collection at the centers of collapse and should facilitate massive cluster formation.

Identification of molecular clouds in emission maps: a comparison between methods in the \ce{^{13}CO}/\ce{C^{18}O} ($J=3-2$) Heterodyne Inner Milky Way Plane Survey

Authors: Raffaele Rani, Toby J. T. Moore, David J. Eden, Andrew J. Rigby, Ana Duarte-Cabral, Yueh-Ning Lee
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.07874
Pdf link: https://arxiv.org/pdf/2305.07874
Abstract
The growing range of automated algorithms for the identification of molecular clouds and clumps in large observational datasets has prompted the need for the direct comparison of these procedures. However, these methods are complex and testing for biases is often problematic: only a few of them have been applied to the same data set or calibrated against a common standard. We compare the Fellwalker method, a widely used watershed algorithm, to the more recent Spectral Clustering for Interstellar Molecular Emission Segmentation (SCIMES). SCIMES overcomes sensitivity and resolution biases that plague many friends-of-friends algorithms by recasting cloud segmentation as a clustering problem. Considering the \ce{^{13}CO}/\ce{C^{18}O} ($J = 3 - 2$) Heterodyne Inner Milky Way Plane Survey (CHIMPS) and the CO High-Resolution Survey (COHRS), we investigate how these two different approaches influence the final cloud decomposition. Although the two methods produce largely similar statistical results over the CHIMPS dataset, FW appears prone to over-segmentation, especially in crowded fields where gas envelopes around dense cores are identified as adjacent, distinct objects. FW catalogue also includes a number of fragmented clouds that appear as different objects in a line-of-sight projection. In addition, cross-correlating the physical properties of individual sources between catalogues is complicated by different definitions, numerical implementations, and design choices within each method, which make it very difficult to establish a one-to-one correspondence between the sources.

Dynamics of the clumps partially disrupted from a planet around a neutron star

Authors: Abdusattar Kurban, Xia Zhou, Na Wang, Yong-Feng Huang, Yu-Bin Wang, Nurimangul Nurmamat
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.08142
Pdf link: https://arxiv.org/pdf/2305.08142
Abstract
Tidal disruption events are common in the Universe, which may occur in various compact star systems and could account for many astrophysical phenomena. Depending on the separation between the central compact star and its companion, either a full disruption or a partial disruption may occur. The partial disruption of a rocky planet around a neutron star can produce kilometer-sized clumps, but the main portion of the planet can survive. The dynamical evolution of these clumps is still poorly understood. In this study, the characteristics of partial disruption of a rocky planet in a highly elliptical orbit around a neutron star is investigated. The periastron of the planet is assumed to be very close to the neutron star so that it would be partially disrupted by tidal force every time it passes through the periastron. It is found that the fragments generated in the process will change their orbits on a time scale of a few orbital periods due to the combined influence of the neutron star and the remnant planet, and will finally collide with the central neutron star. Possible outcomes of the collisions are discussed.

Fast rotating Blue Stragglers prefer loose clusters

Authors: Francesco R. Ferraro, Alessio Mucciarelli, Barbara Lanzoni, Cristina Pallanca, Mario Cadelano, Alex Billi, Alison Sills, Enrico Vesperini, Emanuele Dalessandro, Giacomo Beccari, Lorenzo Monaco, Mario Mateo
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.08478
Pdf link: https://arxiv.org/pdf/2305.08478
Abstract
Blue stragglers are anomalously luminous core hydrogen-burning stars formed through mass-transfer in binary/triple systems and stellar collisions. Their physical and evolutionary properties are largely unknown and unconstrained. Here we analyze 320 high-resolution spectra of blue stragglers collected in eight galactic globular clusters with different structural characteristics and show evidence that the fraction of fast rotating blue stragglers (with rotational velocities larger than 40 km/s) increases for decreasing central density of the host system. This trend suggests that fast spinning blue stragglers prefer low-density environments and promises to open an unexplored route towards understanding the evolutionary processes of these stars. Since large rotation rates are expected in the early stages of both formation channels, our results provide direct evidence for recent blue straggler formation activity in low-density environments and put strong constraints on the timescale of the collisional blue straggler slow-down processes.

Full velocities and propagation directions of coronal mass ejections inferred from simultaneous full-disk imaging and Sun-as-a-star spectroscopic observations

Authors: Hong-peng Lu, Hui Tian, He-chao Chen, Yu Xu, Zhen-yong Hou, Xian-yong Bai, Guang-yu Tan, Zi-hao Yang, Jie Ren
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.08765
Pdf link: https://arxiv.org/pdf/2305.08765
Abstract
Coronal mass ejections (CMEs) are violent ejections of magnetized plasma from the Sun, which can trigger geomagnetic storms, endanger satellite operations and destroy electrical infrastructures on the Earth. After systematically searching Sun-as-a-star spectra observed by the Extreme-ultraviolet Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) from May 2010 to May 2022, we identified eight CMEs associated with flares and filament eruptions by analyzing the blue-wing asymmetry of the O III 52.58 nm line profiles. Combined with images simultaneously taken by the 30.4 nm channel of the Atmospheric Imaging Assembly onboard SDO, the full velocity and propagation direction for each of the eight CMEs are derived. We find a strong correlation between geomagnetic indices (Kp and Dst) and the angle between the CME propagation direction and the Sun-Earth line, suggesting that Sun-as-a-star spectroscopic observations at EUV wavelengths can potentially help to improve the prediction accuracy of the geoeffectiveness of CMEs. Moreover, an analysis of synthesized long-exposure Sun-as-a-star spectra implies that it is possible to detect CMEs from other stars through blue-wing asymmetries or blueshifts of spectral lines.

Spatial and Temporal Analysis of Quiescent Coronal Rain over an Active Region

Authors: Seray Şahin, Patrick Antolin, Clara Froment, Thomas A. Schad
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.08775
Pdf link: https://arxiv.org/pdf/2305.08775
Abstract
The solar corona produces coronal rain, hundreds of times colder and denser material than the surroundings. Coronal rain is known to be deeply linked to coronal heating, but its origin, dynamics, and morphology are still not well understood. The leading theory for its origin is thermal instability (TI) occurring in coronal loops in a state of thermal non-equilibrium (TNE), the TNE-TI scenario. Under steady heating conditions, TNE-TI repeats in cycles, leading to long-period EUV intensity pulsations and periodic coronal rain. In this study, we investigate coronal rain on the large spatial scales of an active region (AR) and over the long temporal scales of EUV intensity pulsations to elucidate its distribution at such scales. We conduct a statistical study of coronal rain observed over an AR off-limb with IRIS and SDO imaging data, spanning chromospheric to transition region (TR) temperatures. The rain is widespread across the AR, irrespective of the loop inclination, and with minimal variation over the 5.45-hour duration of the observation. Most rain has a downward ($87.5%$) trajectory; however, upward motions ($12.5%$) are also ubiquitous. The rain dynamics are similar over the observed temperature range, suggesting that the TR and chromospheric emission are co-located on average. The average clump widths and lengths are similar in the SJI channels and wider in the AIA 304 channel. We find ubiquitous long-period EUV intensity pulsations in the AR. Short-term periodicity is found (16 min) linked to the rain appearance, which constitutes a challenge to explain under the TNE-TI scenario.

by olozhika (Xing Yuchen).

2023-05-16

New submissions for Thu, 1 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 9papers

Reversing the verdict: cataclysmic variables could be the dominant progenitors of AM CVn binaries after all

Authors: Diogo Belloni, Matthias R. Schreiber
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.19312
Pdf link: https://arxiv.org/pdf/2305.19312
Abstract
Context. AM CVn binaries, that is, systems in which a white dwarf accretes matter from a helium-rich (semi-)degenerate object, are potential progenitors of thermonuclear supernovae and strong sources of persistent gravitational wave radiation. For a long time, it has been believed that these systems cannot descend from cataclysmic variables (CVs), at least not in large numbers, because the initial conditions need to be fine-tuned and, even worse, the resulting surface hydrogen abundance would be high enough to be detected which contradicts a defining feature of AM CVn binaries. Aims. Here we show that both claimed weaknesses of the CV formation channel for AM CVn binaries are model-dependent and rely on poorly constrained assumptions for magnetic braking. Methods. We performed binary evolution simulations with the MESA code for different combinations of post-common-envelope white dwarf and companion masses as well as orbital periods assuming strong magnetic braking. Results. We found that AM CVn binaries with extremely-low surface hydrogen abundances are one natural outcome of CV evolution if the donor star has developed a non-negligible helium core prior to the onset of mass transfer. In this case, after hydrogen envelope exhaustion during CV evolution, the donor becomes degenerate and its surface hydrogen abundance substantially drops and becomes undetectable. Our simulations also show that the CV formation channel is able to explain the observed AM CVn binaries with very low mass and bloated donor stars (Gaia14aae and ZTF J1637+49) which has not been demonstrated for any alternative formation channel. Conclusions. CVs with evolved donors are likely the progenitors of at least a fraction of AM CVn binaries.

The far side of the Galactic bulge revealed through semi-regular variables

Authors: Daniel R. Hey, Daniel Huber, Benjamin J. Shappee, Joss Bland-Hawthorn, Thor Tepper-García, Robyn Sanderson, Sukanya Chakrabarti, Nicholas Saunders, Jason A. S. Hunt, Timothy R. Bedding, John Tonry
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.19319
Pdf link: https://arxiv.org/pdf/2305.19319
Abstract
The Galactic bulge and bar are critical to our understanding of the Milky Way. However, due to the lack of reliable stellar distances, the structure and kinematics of the bulge/bar beyond the Galactic center have remained largely unexplored. Here, we present a method to measure distances of luminous red giants using a period-amplitude-luminosity relation anchored to the Large Magellanic Cloud, with random uncertainties of 10-15% and systematic errors below 1-2%. We apply this method to data from the Optical Gravitational Lensing Experiment (OGLE) to measure distances to $190,302$ stars in the Galactic bulge and beyond out to 20 kpc. Using this sample we measure a distance to the Galactic center of $R_0$ = $8108\pm106_{\rm stat}\pm93_{\rm sys}$ pc, consistent with astrometric monitoring of stars orbiting Sgr A*. We cross-match our distance catalog with Gaia DR3 and use the subset of $39,566$ overlapping stars to provide the first constraints on the Milky Way's velocity field ($V_R,V_\phi,V_z$) beyond the Galactic center. We show that the $V_R$ quadrupole from the bar's near side is reflected with respect to the Galactic center, indicating that the bar is both bi-symmetric and aligned with the inner disk, and therefore dynamically settled along its full extent. We also find that the vertical height $V_Z$ map has no major structure in the region of the Galactic bulge, which is inconsistent with a current episode of bar buckling. Finally, we demonstrate with N-body simulations that distance uncertainty plays a major factor in the alignment of the major and kinematic axes of the bar and distribution of velocities, necessitating caution when interpreting results for distant stars.

Mid-to-Late M Dwarfs Lack Jupiter Analogs

Authors: Emily K Pass, Jennifer G Winters, David Charbonneau, Jonathan M Irwin, David W Latham, Perry Berlind, Michael L Calkins, Gilbert A Esquerdo, Jessica Mink
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.19357
Pdf link: https://arxiv.org/pdf/2305.19357
Abstract
Cold Jovian planets play an important role in sculpting the dynamical environment in which inner terrestrial planets form. The core accretion model predicts that giant planets cannot form around low-mass M dwarfs, although this idea has been challenged by recent planet discoveries. Here, we investigate the occurrence rate of giant planets around low-mass (0.1-0.3M$\odot$) M dwarfs. We monitor a volume-complete, inactive sample of 200 such stars located within 15 parsecs, collecting four high-resolution spectra of each M dwarf over six years and performing intensive follow-up monitoring of two candidate radial-velocity variables. We use TRES on the 1.5 m telescope at the Fred Lawrence Whipple Observatory and CHIRON on the Cerro Tololo Inter-American Observatory 1.5 m telescope for our primary campaign, and MAROON-X on Gemini North for high-precision follow-up. We place a 95%-confidence upper limit of 1.5% (68%-confidence limit of 0.57%) on the occurrence of $M{\rm P}$sin$i > $1M${\rm J}$ giant planets out to the water snow line and provide additional constraints on the giant planet population as a function of $M{\rm P}$sin$i$ and period. Beyond the snow line ($100$ K $< T_{\rm eq} < 150$ K), we place 95%-confidence upper limits of 1.5%, 1.7%, and 4.4% (68%-confidence limits of 0.58%, 0.66%, and 1.7%) for 3M${\rm J} < M{\rm P}$sin$i < 10$M${\rm J}$, 0.8M${\rm J} < M_{\rm P}$sin$i < 3$M${\rm J}$, and 0.3M${\rm J} < M_{\rm P}$sin$i < 0.8$M$_{\rm J}$ giant planets; i.e., Jupiter analogs are rare around low-mass M dwarfs. In contrast, surveys of Sun-like stars have found that their giant planets are most common at these Jupiter-like instellations.

Day-night transport induced chemistry and clouds on WASP-39b I: Gas-phase composition

Authors: Shang-Min Tsai, Julianne I. Moses, Diana Powell, Elspeth K.H. Lee
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.19403
Pdf link: https://arxiv.org/pdf/2305.19403
Abstract
JWST has recently detected the first robust photochemical product on an exoplanet: sulfur dioxide (SO$_2$) on WASP-39b (Rustamkulov et al. 2023; Alderson et al. 2023; Tsai et al. 2023b). The data from the NIRISS instrument also reveal signs of partial coverage of clouds (Feinstein et al. 2023). Most of the previous studies have focused on interpreting spectral data with 1D models. To explore how the chemical species and cloud particles are altered by global circulation, we applied a 2D photochemical model and a 2D microphysical cloud model separately to post-process the thermal and dynamical structures simulated by a 3D general circulation model (GCM) of WASP-39b. We found that SO$_2$ produced by photochemistry on the dayside can be transported to the nightside owing to the efficient replenishment of horizontal transport. The morning-evening limb differences in methane (CH$_4$) abundances predicted by the 1D models disappeared after horizontal transport is included. Similarly, the inclusion of horizontal transport also reduced the limb differences in SO$_2$. Our modeling results suggest that the fast zonal wind results in minimal or negligible limb asymmetry in composition. Based on the synthetic spectra generated by our 2D atmosphere simulations, we propose that observing SO$_2$ absorption in the emission spectra of WASP-39b at different phases may offer opportunities to probe the horizontal quenching process of photochemical products. We will focus on the gas-phase chemistry in this paper and leave the results regarding clouds in the subsequent paper as part of the series.

Featureless transmission spectra of 12 giant exoplanets observed by GTC/OSIRIS

Authors: C. Jiang, G. Chen, E. Pallé, F. Murgas, H. Parviainen, Y. Ma
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.19441
Pdf link: https://arxiv.org/pdf/2305.19441
Abstract
Exoplanet atmospheres are the key to understanding the nature of exoplanets. To this end, transit spectrophotometry provides us opportunities to investigate the physical properties and chemical compositions of exoplanet atmospheres. We aim to detect potential atmospheric signatures in 12 gaseous giant exoplanets using transit spectrophotometry and we try to constrain their atmospheric properties. The targets of interest were observed using transit spectrophotometry with the GTC OSIRIS instrument. We estimated the transit parameters and obtained the optical transmission spectra of the target planets using a Bayesian framework. We analyzed the spectral features in the transmission spectra based on atmospheric retrievals. Most of the observed transmission spectra were found to be featureless, with only the spectrum of CoRoT-1b showing strong evidence for atmospheric features. However, in combination with the previously published near-infrared transmission spectrum, we found multiple interpretations for the atmosphere of CoRoT-1b due to the lack of decisive evidence for alkali metals or optical absorbers. Featureless spectra are not necessarily indicative of cloudy atmospheres if they poorly constrain the altitudes of cloud decks. Precise constraints on the models of hazes and clouds strongly depend on the significance of the observed spectral features. Further investigations on these exoplanets, especially CoRoT-1b, are required to confirm the properties of their atmospheres.

Chemo-Dynamical Tagging in the Outskirts: The Origins of Stellar Substructures in the Magellanic Clouds

Authors: César Muñoz, Antonela Monachesi, David L. Nidever, Steven R. Majewski, Xinlun Cheng, Knut Olsen, Yumi Choi, Paul Zivick, Douglas Geisler, Andres Almeida, Ricardo R. Muñoz, Christian Nitschelm, Alexandre Roman-Lopes, Richard R. Lane, José G. Fernández-Trincado
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.19460
Pdf link: https://arxiv.org/pdf/2305.19460
Abstract
We present the first detailed chemical analysis from APOGEE-2S observations of stars in six regions of recently discovered substructures in the outskirts of the Magellanic Clouds (MCs) extending to 20 degrees from the Large MC (LMC) center. We also present, for the first time, the metallicity and alpha-abundance radial gradients of the LMC and SMC out to 11 degrees and 6 degrees, respectively. Our chemical tagging includes 13 species including light, alpha, and Fe-peak elements. We find that the abundances of all of these chemical elements in stars populating two regions in the northern periphery - along the northern "stream"-like feature - show good agreement with the chemical patterns of the LMC, and thus likely have an LMC origin. For substructures located in the southern periphery of the LMC, we find more complex chemical and kinematical signatures, indicative of a mix of LMC-like and SMC-like populations. However, the southern region closest to the LMC shows better agreement with the LMC, whereas that closest to the SMC shows a much better agreement with the SMC chemical pattern. When combining this information with 3-D kinematical information for these stars, we conclude that the southern region closest to the LMC has likely an LMC origin, whereas that closest to the SMC has an SMC origin, and the other two southern regions have a mix of LMC and SMC origins. Our results add to the evidence that the southern substructures of the LMC periphery are the product of close interactions between the LMC and SMC, and thus likely hold important clues that can constrain models of their detailed dynamical histories.

A high-resolution spectroscopic analysis of aminoacrylonitrile and an interstellar search towards G+0.693

Authors: D. Alberton, V. Lattanzi, C. Endres, V. M. Rivilla, J.C. Guillemin, P. Caselli, I. Jiménez-Serra, J. Martín-Pintado
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.19641
Pdf link: https://arxiv.org/pdf/2305.19641
Abstract
Cyanides, ranging from three carbon atoms to PAHs, and alkenyl compounds are abundant in the interstellar medium (ISM). Aminoacrylonitrile (3-Amino-2-propenenitrile, H$_{2}$N-CH=CH-CN), an alkenyl cyanide, thus represents a promising candidate for new interstellar detection. A comprehensive spectroscopic laboratory investigation of aminoacrylonitrile in its rotational ground vibrational state has been herein performed. The measurements carried out up to the THz regime made it possible to generate a precise set of reliable rest frequencies for its search in space up to sub-millimetre wavelengths. The $Z$-aminoacrylonitrile ($Z$-apn) isomer spectrum has been recorded employing a source-modulated sub-millimetre spectrometer, from 80 GHz to 1 THz. A combination of Doppler and sub-Doppler measurement regimes allowed to record 600 new lines. The collected data have enabled the characterisation of a set of spectroscopic parameters up to decic centrifugal distortion constants. The catalogue generated from the improved spectral data has been used for the search of $Z$-apn in the spectral survey of the G+0.693-0.027 molecular cloud located in the central molecular zone, in the proximity of the Galactic centre.

Expulsion of counter Evershed flows from sunspot penumbrae

Authors: J.S. Castellanos Durán, A. Korpi-Lagg, S.K. Solanki
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2305.19705
Pdf link: https://arxiv.org/pdf/2305.19705
Abstract
In addition to the Evershed flow directed from the umbra towards the outer boundary of the sunspot, under special circumstances, a counter Evershed flow (CEF) in the opposite direction also occurs. We aim to characterize the proper motions and evolution of three CEFs observed by the Solar Optical Telescope onboard the Japanese Hinode spacecraft and the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory. We use state-of-the-art inversions of the radiative transfer equation of polarized light applied to spectropolarimetric observations of the Fe I line pair around 630 nm. The three CEFs appeared within the penumbra. Two of the CEF structures, as part of their decay process, were found to move radially outwards through the penumbra parallel to the penumbral filaments with speeds, deduced from their proper motions, ranging between 65 and 117 m/s. In these two cases, a new spot appeared in the moat of the main sunspot after the CEFs reached the outer part of the penumbra. Meanwhile, the CEFs moved away from the umbra, and their magnetic field strengths decreased. The expulsion of these two CEFs seems to be related to the normal Evershed flow. The third CEF appeared to be dragged by the rotation of a satellite spot. Chromospheric brightenings were found to be associated with the CEFs, and those CEFs that reached the umbra-penumbra boundary showed enhanced chromospheric activity. The two CEFs, for which line-of-sight velocity maps were available during their formation phase, appear as intrusions into the penumbra. They may be associated with magnetic flux emergence.

AFGL 5180 and AFGL 6366S: sites of hub-filament systems at the opposite edges of a filamentary cloud

Authors: A. K. Maity, L. K. Dewangan, N. K. Bhadari, D. K. Ojha, Z. Chen, Rakesh Pandey
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.19751
Pdf link: https://arxiv.org/pdf/2305.19751
Abstract
We present a multi-scale and multi-wavelength study to unveil massive star formation (MSF) processes around sites AFGL 5180, and AFGL 6366S, both hosting a Class II 6.7 GHz methanol maser emission. The radio continuum map at 8.46 GHz reveals a small cluster of radio sources toward AFGL 5180. Signatures of the early stages of MSF in our target sites are spatially seen at the opposite edges of a filamentary cloud (length $\sim$5 pc), which is observed in the sub-millimeter dust continuum maps. Using the near-infrared photometric data, the spatial distribution of young stellar objects is found toward the entire filament, primarily clustered at its edges. The getsf utility on the Herschel far-infrared images reveals a hub-filament system (HFS) toward each target site. The analysis of the molecular line data, which benefits from large area coverage ($\sim$1 degree $\times$ 1 degree), detects two cloud components with a connection in both position and velocity space. This supports the scenario of a cloud-cloud collision (CCC) that occurred $\sim$1 Myr ago. The filamentary cloud, connecting AFGL 5180 and AFGL 6366S, seems spatially close to an HII region Sh2-247 excited by a massive O9.5 star. Based on the knowledge of various pressures exerted by the massive star on its surroundings, the impact of its energetic feedback on the filamentary cloud is found to be insignificant. Overall, our observational outcomes favor the possibility of the CCC scenario driving MSF and the formation of HFSs toward the target sites.

by olozhika (Xing Yuchen).

2023-06-01

New submissions for Tue, 2 May 23

Update Star Formation & Molecular Cloud papers at 2am UTC (10am Beijing time) every weekday.
forked from zhuhu00/Paper-Daily-Notice.
2023-05-02

Keyword list: ['star formation', 'molecular cloud', 'N-PDF', 'cloud', 'interstellar medium', 'core', 'filament', 'atomic gas']

Today: 6papers

Recent Progress in Modelling the Macro- and Micro-Physics of Radio Jet Feedback in Galaxy Clusters

Authors: Martin A. Bourne, Hsiang-Yi Karen Yang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00019
Pdf link: https://arxiv.org/pdf/2305.00019
Abstract
Radio jets and the lobes they inflate are common in cool-core clusters and are expected to play a critical role in regulating the heating and cooling of the intracluster medium (ICM). This is an inherently multi-scale problem, and much effort has been made to understand the processes governing the inflation of lobes and their impact on the cluster, as well as the impact of the environment on the jet-ICM interaction, on both macro- and microphysical scales. Developments of new numerical techniques and improving computational resources have seen simulations of jet feedback in galaxy clusters become ever more sophisticated. This ranges from modelling ICM plasma physics processes such as the effects of magnetic fields, cosmic rays and viscosity to including jet feedback in cosmologically evolved cluster environments in which the ICM thermal and dynamic properties are shaped by large-scale structure formation. In this review, we discuss the progress made over the last ~decade in capturing both the macro- and microphysical processes in numerical simulations, highlighting both the current state of the field as well as open questions and potential ways in which these questions can be addressed in the future.

Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution -- Insights from the IRAM NOEMA large program CORE

Authors: Aida Ahmadi, H. Beuther, F. Bosco, C. Gieser, S. Suri, J. C. Mottram, R. Kuiper, Th. Henning, Á. Sánchez-Monge, H. Linz, R. E. Pudritz, D. Semenov, J. M. Winters, T. Möller, M. T. Beltrán, T. Csengeri, R. Galván-Madrid, K. G. Johnston, E. Keto, P. D. Klaassen, S. Leurini, S. N. Longmore, S. L. Lumsden, L. T. Maud, L. Moscadelli, A. Palau, T. Peters, S. E. Ragan, J. S. Urquhart, Q. Zhang, H. Zinnecker
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.00020
Pdf link: https://arxiv.org/pdf/2305.00020
Abstract
The fragmentation mode of high-mass molecular clumps and the accretion processes that form the most massive stars ($M\gtrsim 8M_\odot$) are still not well understood. To this end, we have undertaken a large observational program (CORE) making use of interferometric observations from the Northern Extended Millimetre Array (NOEMA) for a sample of 20 luminous ($L>10^4L_\odot$) protostellar objects in the 1.37 mm wavelength regime in both continuum and line emission, reaching $\sim$0.4" resolution (800 au at 2 kpc). Using the dense gas tracer CH$3$CN, we find velocity gradients across 13 cores perpendicular to the directions of bipolar molecular outflows, making them excellent disk candidates. Specific angular momentum ($j$) radial profiles are on average $\sim10^{-3}$ km /s pc and follow $j \propto r^{1.7}$, consistent with a poorly resolved rotating and infalling envelope/disk model. Fitting the velocity profiles with a Keplerian model, we find protostellar masses in the range of $\sim 10-25$ $M\odot$. Modelling the level population of CH$_3$CN lines, we present temperature maps and find median gas temperatures in the range $70-210$ K. We create Toomre $Q$ maps to study the stability of the disks and find almost all (11 of 13) disk candidates to be prone to fragmentation due to gravitational instabilities at the scales probed by our observations. In particular, disks with masses greater than $\sim10-20%$ of the mass of their host (proto)stars are Toomre unstable, and more luminous protostellar objects tend to have disks that are more massive and hence more prone to fragmentation. Our finings show that most disks around high-mass protostars are prone to disk fragmentation early in their formation due to their high disk to stellar mass ratio. This impacts the accretion evolution of high-mass protostars which will have significant implications for the formation of the most massive stars.

Machine Learning Uncovers the Universe's Hidden Gems: A Comprehensive Catalogue of CIV Absorption Lines in SDSS DR12

Authors: Reza Monadi, Ming-Feng Ho, Kathy L. Cooksey, Simeon Bird
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00023
Pdf link: https://arxiv.org/pdf/2305.00023
Abstract
We assemble the largest CIV absorption line catalogue to date, leveraging machine learning, specifically Gaussian processes, to remove the need for visual inspection for detecting CIV absorbers. The catalogue contains probabilities classifying the reliability of the absorption system within a quasar spectrum. Our training set was a sub-sample of DR7 spectra that had no detectable CIV absorption in a large visually inspected catalogue. We used Bayesian model selection to decide between our continuum model and our absorption-line models. Using a random hold-out sample of 1301 spectra from all of the 26,030 investigated spectra in DR7 CIV catalogue, we validated our pipeline and obtained an 87% classification performance score. We found good purity and completeness values, both ~80%, when a probability of ~95% is used as the threshold. Our pipeline obtained similar CIV redshifts and rest equivalent widths to our training set. Applying our algorithm to 185,425 selected quasar spectra from SDSS DR12, we produce a catalogue of 113,775 CIV doublets with at least 95% confidence. Our catalogue provides maximum a posteriori values and credible intervals for CIV redshift, column density, and Doppler velocity dispersion. We detect CIV absorption systems with a redshift range of 1.37 $!-!$ 5.1, including 33 systems with a redshift larger than 5 and 549 absorbers systems with a rest equivalent width greater than 2 A at more than 95% confidence. Our catalogue can be used to investigate the physical properties of the circumgalactic and intergalactic media.

Detection of monothioformic acid towards the solar-type protostar IRAS 16293-2422

Authors: Arijit Manna, Sabyasachi Pal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.00480
Pdf link: https://arxiv.org/pdf/2305.00480
Abstract
In the interstellar medium (ISM), the complex organic molecules that contain the thiol group ($-$SH) play an important role in the polymerization of amino acids. We look for SH-bearing molecules in the chemically rich solar-type protostar IRAS 16293-2422. After the extensive spectral analysis using the local thermodynamic equilibrium (LTE) model, we have detected the rotational emission lines of trans-isomer monothioformic acid (t-HC(O)SH) towards the IRAS 16293 B using the Atacama Large Millimeter/Submillimeter Array (ALMA). We did not observe any evidence of cis-isomer monothioformic acid (c-HC(O)SH) towards the IRAS 16293 B. The column density of t-HC(O)SH towards the IRAS 16293 B was (1.02$\pm$0.6)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 125$\pm$15 K. The fractional abundance of t-HC(O)SH with respect to H${2}$ towards the IRAS 16293 B is 8.50$\times$10$^{-11}$. The column density ratio of t-HC(O)SH/CH${3}$SH towards the IRAS 16293 B is 0.185. We compare our estimated abundance of t-HC(O)SH towards the IRAS 16293 B with the abundance of t-HC(O)SH towards the galactic center quiescent cloud G+0.693-0.027 and hot molecular core G31.41+0.31. After the comparison, we found that the abundance of t-HC(O)SH towards the IRAS 16293 B is several times of magnitude lower than G+0.693-0.027 and G31.41+0.31. We also discuss the possible formation mechanism of t-HC(O)SH in the ISM.

Joint Modelling of Dust Scattering and Thermal Emission: The Spider Complex

Authors: Jielai Zhang, Peter G Martin, Ryan Cloutier, Natalie Price-Jones, Roberto Abraham, Pieter van Dokkum, Allison Merritt
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.00756
Pdf link: https://arxiv.org/pdf/2305.00756
Abstract
Observations across the electromagnetic spectrum of radiative processes involving interstellar dust -- emission, extinction, and scattering -- are used to constrain the parameters of dust models and more directly to aid in foreground removal of dust for extragalactic and cosmology observations. The more complementary observations, the better. Here, we quantify the relationship between scattered light and thermal emission from dust in a diffuse (cirrus) intermediate latitude cloud, Spider, using data from the Dragonfly Telephoto Array and the Herschel Space Observatory. A challenge for optical observations of faint cirrus is accurate removal of a contaminating spatially varying sky background. We present a technique to analyse two images of the same cirrus field concurrently, correlating pixel values to capture the relationship and simultaneously fitting the sky background as a complex non-correlating additive component. For the Spider, we measure a $g-r$ color of 0.644$\pm 0.024$ and a visible wavelength to 250 $\mu$m intensity ratio of $10^{-3} \times (0.855 \pm0.025)$ and $10^{-3} \times (1.55\pm0.08)$ for $g$ and $r$-band respectively. We show how to use any dust model that matches the thermal dust emission to predict an upper limit to the amount of scattered light. The actual brightness of the cirrus will be fainter than this limit because of anisotropic scattering by the dust combined with anisotropy of the incident interstellar radiation field (ISRF). Using models of dust and the ISRF in the literature we illustrate that the predicted brightness is indeed lower, though not as faint as the observations indicate.

Small Planets Around Cool Dwarfs: Enhanced Formation Efficiency of Super-Earths around M dwarfs

Authors: Yayaati Chachan, Eve J. Lee
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.00803
Pdf link: https://arxiv.org/pdf/2305.00803
Abstract
Current measurements of planet population as a function of stellar mass show three seemingly contradictory signatures: close-in super-Earths are more prevalent around M dwarfs than FGK dwarfs; inner super-Earths are correlated with outer giants; and outer giants are less common around M dwarfs than FGK dwarfs. Here, we build a simple framework that combines the theory of pebble accretion with the measurements of dust masses in protoplanetary disks to reconcile all three observations. First, we show that cooler stars are more efficient at converting pebbles into planetary cores at short orbital periods. Second, when disks are massive enough to nucleate a heavy core at 5 AU, more than enough dust can drift in to assemble inner planets, establishing the correlation between inner planets and outer giants. Finally, while stars of varying masses are similarly capable of converting pebbles into cores at long orbital periods, hotter stars are much more likely to harbor more massive dust disks so that the giant planet occurrence rate rises around hotter stars. Our results are valid over a wide range of parameter space for a disk accretion rate that follows $\dot{M}\star \sim 10^{-8},M\odot,{\rm yr}^{-1}(M_\star/M_\odot)^2$. We predict a decline in mini-Neptune population (but not necessarily terrestrial planets) around stars lighter than $\sim 0.3-0.5 , M_\odot$. Cold giants ($\gtrsim$5 AU), if they exist, should remain correlated with inner planets even around lower mass stars.

New submissions for Wed, 31 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 5papers

Gravitational waves from binary black holes in a self-interacting scalar dark matter cloud

Authors: Alexis Boudon, Philippe Brax, Patrick Valageas, Leong Khim Wong
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Arxiv link: https://arxiv.org/abs/2305.18540
Pdf link: https://arxiv.org/pdf/2305.18540
Abstract
We investigate the imprints of accretion and dynamical friction on the gravitational-wave signals emitted by binary black holes embedded in a scalar dark matter cloud. As a key feature in this work, we focus on scalar fields with a repulsive self-interaction that balances against the self-gravity of the cloud. To a first approximation, the phase of the gravitational-wave signal receives extra correction terms at $-4$PN and $-5.5$PN orders, relative to the prediction of vacuum general relativity, due to accretion and dynamical friction, respectively. Future observations by LISA and B-DECIGO have the potential to detect these effects for a large range of scalar masses~$m_\mathrm{DM}$ and self-interaction couplings~$\lambda_4$; observations by ET and Advanced~~LIGO could also detect these effects, albeit in a more limited region of parameter space. Crucially, we find that even if a dark matter cloud has a bulk density~~$\rho_0$ that is too dilute to be detected via the effects of dynamical friction, the imprints of accretion could still be observable because it is controlled by the independent scale $\rho_a = 4 m_{\rm DM}^4 c^3/(3 \lambda_4 \hbar^3)$. In the models we consider, the infalling dark matter increases in density up to this characteristic scale $\rho_a$ near the Schwarzschild radius, which sets the accretion rate and its associated impact on the gravitational~waveform.

JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B

Authors: K. L. Luhman, P. Tremblin, S. M. Birkmann, E. Manjavacas, J. Valenti, C. Alves de Oliveira, T. L. Beck, G. Giardino, N. Lutzgendorf, B. J. Rauscher, M. Sirianni
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.18603
Pdf link: https://arxiv.org/pdf/2305.18603
Abstract
We present 1-5um spectroscopy of the young planetary mass companion TWA 27B (2M1207B) performed with NIRSpec on board the James Webb Space Telescope. In these data, the fundamental band of CH_4 is absent and the fundamental band of CO is weak. The nondetection of CH_4 reinforces a previously observed trend of weaker CH_4 with younger ages among L dwarfs, which has been attributed to enhanced non-equilibrium chemistry among young objects. The weakness of CO may reflect an additional atmospheric property that varies with age, such as the temperature gradient or cloud thickness. We are able to reproduce the broad shape of the spectrum with an ATMO cloudless model that has T=1300 K, non-equilibrium chemistry, and a temperature gradient reduction caused by fingering convection. However, the fundamental bands of CH_4 and CO are somewhat stronger in the model. In addition, the model temperature of 1300 K is higher than expected from evolutionary models given the luminosity and age of TWA 27B (T=1200 K). Previous models of young L-type objects suggest that the inclusion of clouds could potentially resolve these issues; it remains to be seen whether cloudy models can provide a good fit to the 1-5um data from NIRSpec. TWA 27B exhibits emission in Paschen transitions and the He I triplet at 1.083um, which are signatures of accretion that provide the first evidence of a circumstellar disk. We have used the NIRSpec data to estimate the bolometric luminosity of TWA 27B (log L/L_sun=-4.466+/-0.014), which implies a mass of 5-6 MJup according to evolutionary models.

FacetClumps: A Facet-based Molecular Clump Detection Algorithm

Authors: Yu Jiang, Zhiwei Chen, Sheng Zheng, Zhibo Jiang, Yao Huang, Shuguang Zeng, Xiangyun Zeng, Xiaoyu Luo
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2305.18709
Pdf link: https://arxiv.org/pdf/2305.18709
Abstract
A comprehensive understanding of molecular clumps is essential for investigating star formation. We present an algorithm for molecular clump detection, called FacetClumps. This algorithm uses a morphological approach to extract signal regions from the original data. The Gaussian Facet model is employed to fit the signal regions, which enhances the resistance to noise and the stability of the algorithm in diverse overlapping areas. The introduction of the extremum determination theorem of multivariate functions offers theoretical guidance for automatically locating clump centers. To guarantee that each clump is continuous, the signal regions are segmented into local regions based on gradient, and then the local regions are clustered into the clump centers based on connectivity and minimum distance to identify the regional information of each clump. Experiments conducted with both simulated and synthetic data demonstrate that FacetClumps exhibits great recall and precision rates, small location error and flux loss, a high consistency between the region of detected clump and that of simulated clump, and is generally stable in various environments. Notably, the recall rate of FacetClumps in the synthetic data, which comprises $^{13}CO$ ($J = 1-0$) emission line of the MWISP within $11.7^{\circ} \leq l \leq 13.4^{\circ}$, $0.22^{\circ} \leq b \leq 1.05^{\circ}$ and 5 km s$^{-1}$ $\leq v \leq$ 35 km s$^{-1}$ and simulated clumps, reaches 90.2%. Additionally, FacetClumps demonstrates satisfactory performance when applied to observational data.

Amides inventory towards the G+0.693-0.027 molecular cloud

Authors: S. Zeng, V. M. Rivilla, I. Jiménez-Serra, L. Colzi, J. Martín-Pintado, B. Tercero, P. de Vicente, S. Martín, M. A. Requena-Torres
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.18715
Pdf link: https://arxiv.org/pdf/2305.18715
Abstract
Interstellar amides have attracted significant attentions as they are potential precursors for a wide variety of organics essential to life. However, our current understanding of their formation in space is heavily based on observations in star-forming regions and hence the chemical networks lack the constraints on their early origin. In this work, unbiased sensitive spectral surveys with IRAM 30m and Yebes 40m telescopes are used to systematically study a number of amides towards a quiescent Galactic Centre molecular cloud, G+0.693-0.027. We report the first detection of acetamide (CH3C(O)NH2) and trans-N-methylformamide (CH3NHCHO) towards this cloud. In addition, with the wider frequency coverage of the survey, we revisited the detection of formamide (NH2CHO) and urea (carbamide; NH2C(O)NH2), which had been reported previously towards G+0.693-0.027. Our results are compared with those present in the literature including recent laboratory experiments and chemical models. We find constant abundance ratios independently of the evolutionary stages, suggesting that amides related chemistry is triggered in early evolutionary stages of molecular cloud and remain unaffected by the warm-up phase during the star formation process. Although a correlation between more complex amides and NH2CHO have been suggested, alternative formation routes involving other precursors such as acetaldehyde (CH3CHO), methyl isocyanate (CH3NCO) and methylamine (CH3NH2) may also contribute to the production of amides. Observations of amides together with these species towards a larger sample of sources can help to constrain the amide chemistry in the interstellar medium.

GMCs and their Type classification in M74: Toward understanding star formation and cloud evolution

Authors: F. Demachi, Y. Fukui, R. I. Yamada, K. Tachihara, T. Hayakawa, K. Tokuda, S. Fujita, M. I. N. Kobayashi, K. Muraoka, A. Konishi, K. Tsuge, T. Onishi, A. Kawamura
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.19192
Pdf link: https://arxiv.org/pdf/2305.19192
Abstract
We investigated the giant molecular clouds (GMCs) in M74 (NGC 628) obtained by the PHANGS project. We applied the GMC Types according to the activity of star formation: Type I without star formation, Type II with H$\alpha$ luminosity ($L_{\mathrm{H\alpha}}$) smaller than $10^{37.5} \mathrm{erg~~s^{-1}}$, and Type III with $L_{\mathrm{H\alpha}}$ greater than $10^{37.5} \mathrm{erg~~s^{-1}}$. In total, 432 GMCs were identified, where the individual GMC Types are 65, 203, and 164, for Type I, Type II, and Type III, respectively. The size and mass of the GMCs range from 23 - 237 pc and $10^{4.9}$ - $10^{7.1}$ M$_{\odot}$, showing a trend that mass and radius increase from Type I to II to III. Clusters younger than 4 Myr and HII regions are found to be concentrated within 150 pc of a GMC, indicating a tight association of these young objects with the GMCs. The virial ratio tends to decrease from Type I to III, indicating that Type III GMCs are most relaxed gravitationally among the three. We interpret that GMCs evolve from Type I to III, as previously found in the LMC. The evolutionary timescales of the three Types are estimated to be 2 Myr, 6 Myr, and 4 Myr, respectively, on a steady state assumption, where we assume the timescale of Type III is equal to the age of the associated clusters, indicating a GMC lifetime of 12 Myr or longer. Chevance et al. (2020) investigated GMCs using the same PHANGS dataset of M74, while these authors did not define a GMC, reaching an evolutionary picture with a 20 Myr duration of the non-star forming phase, five times longer than 4 Myr. We compare the present results with those by Chevance et al. (2020) and argue that defining individual GMCs is essential to understanding GMC evolution.

by olozhika (Xing Yuchen).

2023-05-31

New submissions for Wed, 21 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 19papers

On the pollution of white dwarfs by exo-Oort cloud comets

Authors: Christopher E. O'Connor, Dong Lai, Darryl Z. Seligman
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.10102
Pdf link: https://arxiv.org/pdf/2306.10102
Abstract
A large fraction of white dwarfs (WDs) have metal-polluted atmospheres, which are produced by accreting material from remnant planetary systems. The composition of the accreted debris broadly resembles that of rocky Solar System objects. Volatile-enriched debris with compositions similar to long-period comets (LPCs) is rarely observed. We attempt to reconcile this dearth of volatiles with the premise that exo-Oort clouds (XOCs) occur around a large fraction of planet-hosting stars. We estimate the comet accretion rate from an XOC analytically, adapting the 'loss cone' theory of LPC delivery in the Solar System. We investigate the dynamical evolution of an XOC during late stellar evolution. Using numerical simulations, we show that 1 to 30 per cent of XOC objects remain bound after anisotropic stellar mass loss imparting a WD natal kick of $\sim$1 km/s. We also characterize the surviving comets' distribution function. Surviving planets orbiting a WD can prevent the accretion of XOC comets by the star. A planet's 'dynamical barrier' is effective at preventing comet accretion if the energy kick imparted by the planet exceeds the comet's orbital binding energy. By modifying the loss cone theory, we calculate the amount by which a planet reduces the WD's accretion rate. We suggest that the scarcity of volatile-enriched debris in polluted WDs is caused by an unseen population of 10-100 AU scale giant planets acting as barriers to incoming LPCs. Finally, we constrain the amount of volatiles delivered to a planet in the habitable zone of an old, cool WD.

Long-Term Evolution of Massive-Star Post-Common Envelope Circumbinary Disks and the Environments of Fast Luminous Transients

Authors: Semih Tuna, Brian D. Metzger
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.10111
Pdf link: https://arxiv.org/pdf/2306.10111
Abstract
If the envelope of a massive star is not entirely removed during common envelope (CE) interaction with an orbiting compact (e.g., black hole [BH] or neutron star [NS]) companion, the residual bound material eventually cools, forming a centrifugally-supported disk around the binary containing the stripped He core. We present a time-dependent height-integrated model for the long-term evolution of post-CE circumbinary disks (CBD), accounting for mass and angular momentum exchange with the binary and irradiation heating by the He core and photoevaporation wind mass-loss. A large fraction of the CBD's mass is accreted prior to its outwards viscous spreading and wind-dispersal on a timescale ~10^{4}-10^{5} yr, driving significant changes in the binary separation, even for disks containing ~ 10% of the original envelope mass. Insofar that the CBD lifetime is comparable to the thermal (and, potentially, nuclear) timescale of the He core, over which a second mass-transfer episode onto the companion can occur, the presence of the CBD could impact the stability of this key phase. Disruption of the He core by the BH/NS would result in a jetted energetic explosion into the dense gaseous CBD (<~~10^{15} cm) and its wind (>~~ 10^{16} cm), consistent with the environments of luminous fast blue optical transients like AT2018cow. Evolved He cores which undergo core-collapse still embedded in their CBD could generate Type Ibn/Icn supernovae. Thousands of dusty wind-shrouded massive-star CBD may be detectable as extragalactic luminous infrared sources with the Roman Space Telescope; synchrotron radio nebulae powered by the CBD-fed BH/NS may accompany these systems.

No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c

Authors: Sebastian Zieba, Laura Kreidberg, Elsa Ducrot, Michaël Gillon, Caroline Morley, Laura Schaefer, Patrick Tamburo, Daniel D. B. Koll, Xintong Lyu, Lorena Acuña, Eric Agol, Aishwarya R. Iyer, Renyu Hu, Andrew P. Lincowski, Victoria S. Meadows, Franck Selsis, Emeline Bolmont, Avi M. Mandell, Gabrielle Suissa
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.10150
Pdf link: https://arxiv.org/pdf/2306.10150
Abstract
Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System (Gillon et al., 2017). Thanks to the recent launch of JWST, possible atmospheric constituents such as carbon dioxide (CO2) are now detectable (Morley et al., 2017, Lincowski et al., 2018}. Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO2 in its atmosphere (Greene et al., 2023). Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 micron. We measure a planet-to-star flux ratio of fp/fs = 421 +/- 94 parts per million (ppm) which corresponds to an inferred dayside brightness temperature of 380 +/- 31 K. This high dayside temperature disfavours a thick, CO2-rich atmosphere on the planet. The data rule out cloud-free O2/CO2 mixtures with surface pressures ranging from 10 bar (with 10 ppm CO2) to 0.1 bar (pure CO2). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6 sigma confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio. The absence of a thick, CO2-rich atmosphere on TRAPPIST-1 c suggests a relatively volatile-poor formation history, with less than 9.5 +7.5 -2.3 Earth oceans of water. If all planets in the system formed in the same way, this would indicate a limited reservoir of volatiles for the potentially habitable planets in the system.

Multi-wavelength temporal variability of the blazar PKS 1510-089

Authors: Q. Yuan, Pankaj Kushwaha, Alok C. Gupta, Ashutosh Tripathi, Paul J. Wiita, M. Zhang, X. Liu, Anne Lahteenmaki, Merja Tornikoski, Joni Tammi, Venkatessh Ramakrishnan, L. Cui, X. Wang, M. F. Gu, Cosimo Bambi, A. E. Volvach
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.10248
Pdf link: https://arxiv.org/pdf/2306.10248
Abstract
We perform correlation and periodicity search analyses on long-term multi-band light curves of the FSRQ 1510-089 observed by the space-based Fermi--Large Area Telescope in gamma-rays, the SMARTS and Steward Observatory telescopes in optical and near-infrared (NIR) and the 13.7 m radio telescope in Metsahovi Radio Observatory between 2008 and 2018. The z-transform discrete correlation function method is applied to study the correlation and possible time lags among these multi band light curves. Among all pairs of wavelengths, the gamma-ray vs. optical/NIR and optical vs. NIR correlations show zero time lags; however, both the gamma-ray and optical/NIR emissions precede the radio radiation. The Generalized Lomb-Scargle periodogram, Weighted Wavelet Z-transform, and REDFIT techniques are employed to investigate the unresolved-core-emission dominated 37 GHz light curve and yield evidence for a quasi-period around 1540 days, although given the length of the whole data set it cannot be claimed to be significant. We also investigate the optical/NIR color variability and find that this source shows a simple redder-when-brighter behavior over time, even in the low flux state.

Properties of star formation of the Large Magellanic Cloud as probed by young stellar objects

Authors: Takuma Kokusho, Hiroki Torii, Hidehiro Kaneda, Yasuo Fukui, Kengo Tachihara
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.10258
Pdf link: https://arxiv.org/pdf/2306.10258
Abstract
We perform a systematic study of evolutionary stages and stellar masses of young stellar objects (YSOs) in the Large Magellanic Cloud (LMC) to investigate properties of star formation of the galaxy. There are 4825 sources in our YSO sample, which are constructed by combining the previous studies identifying YSOs in the LMC. Spectral energy distributions of the YSOs from optical to infrared wavelengths were fitted with a model consisting of stellar, polycyclic aromatic hydrocarbon and dust emissions. We utilize the stellar-to-dust luminosity ratios thus derived to study the evolutionary stages of the sources; younger YSOs are expected to show lower stellar-to-dust luminosity ratios. We find that most of the YSOs are associated with the interstellar gas across the galaxy, which are younger with more gases, suggesting that more recent star formation is associated with larger amounts of the interstellar medium (ISM). N157 shows a hint of higher stellar-to-dust luminosity ratios between active star-forming regions in the LMC, suggesting that recent star formation in N157 is possibly in later evolutionary stages. We also find that the stellar mass function tends to be bottom-heavy in supergiant shells (SGSs), indicating that gas compression by SGSs may be ineffective in compressing the ISM enough to trigger massive star formation. There is no significant difference in the stellar mass function between YSOs likely associated with the interface between colliding SGSs and those with a single SGS, suggesting that gas compression by collisions between SGSs may also be ineffective for massive star formation.

Far-Ultraviolet to Near-Infrared Observations of SN 2023ixf: A high energy explosion engulfed in complex circumstellar material

Authors: Rishabh Singh Teja, Avinash Singh, Anirban Dutta, Judhajeet Basu, G.C. Anupama, D.K. Sahu, Vishwajeet Swain, Tatsuya Nakaoka, Utkarsh Pathak, Varun Bhalerao, Sudhanshu Barway, Harsh Kumar, Nayana A.J., Ryo Imazawa, Brajesh Kumar, Koji S Kawabata
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.10284
Pdf link: https://arxiv.org/pdf/2306.10284
Abstract
We present early-phase panchromatic photometric and spectroscopic coverage spanning far-ultraviolet (FUV) to the near-infrared (NIR) regime of the nearest hydrogen-rich core-collapse supernova in the last 25 years, SN~2023ixf. We observe early `flash' features in the optical spectra due to a confined dense circumstellar material (CSM). We observe high-ionization absorption lines Fe II, Mg II in the ultraviolet spectra from very early on. We also observe a multi-peaked emission profile of H-alpha in the spectrum beginning ~16 d, which indicates ongoing interaction of the SN ejecta with a pre-existing shell-shaped CSM having an inner radius of ~ 75 AU and an outer radius of ~140 AU. The shell-shaped CSM is likely a result of enhanced mass loss ~ 35 - 65 years before the explosion assuming a standard Red-Supergiant wind. Spectral modeling of the FUV, NUV, and the optical spectra during 9-12 d, using the radiative transfer spectrum synthesis code TARDIS indicates that the supernova ejecta could be well represented by a progenitor elemental composition greater than solar abundances. Based on early light curve models of Type II SNe, we infer that the nearby dense CSM confined to ~~7+-3e14~~cm(~45 AU) is a result of enhanced mass loss ~1e-(3.0+-0.5) Msol/yr two decades before the explosion.

Collapsing molecular clouds with tracer particles: Part II, Collapse Histories

Authors: David C. Collins, Dan K. Le, Luz L. Jimenez Vela
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.10320
Pdf link: https://arxiv.org/pdf/2306.10320
Abstract
In order to develop a complete theory of star formation, one essentially needs to know two things: what collapses, and how long it takes. This is the second paper in a series, where we query how long a parcel of gas takes to collapse and the process it undergoes. We embed pseudo-Lagrangian tracer particles in simulations of collapsing molecular clouds, identify the particles that end in dense knots, and then examine the collapse history of the gas. We find a nearly universal behavior of cruise-then-collapse. We identify gas the moment before it collapses, $t_{\rm{sing}}$, and examine how it transitions to high density. We find that the time to collapse is uniformly distributed between $0.25 t_{\rm{ff}}$ and the end of the simulation at $\sim 1 t_{\rm{ff}}$, and that the collapse duration is universally short, $\Delta t \sim 0.1 t_{\rm{ff}}$. We find that the collapse of each core happens by a process akin to violent relaxation, wherein a fast reordering of the potential and kinetic energies occurs, in $0.1 t_{\rm{ff}}$, after which a virialized object remains. We describe the collapse in four stages; collection, hardening, singularity, and mosh. Collection sweeps low density gas into moderate density. Hardening brings kinetic and gravitational energies into quasi-equipartition. Singularity is the free-fall collapse, forming a virialized object in $\sim 0.1 t_{\rm{ff}}$. Mosh encompasses tidal dynamics of sub clumps and nearby cores during the collapse. In this work we focus primarily on isolated clumps. With this novel lens we can observe the details of collapse.

Direct observational evidence of the multi-scale, dynamical mass accretion toward a high-mass star forming hub-filament system

Authors: Dongting Yang, Hong-Li Liu, Anandmayee Tej, Tie Liu, Patricio Sanhueza, Sheng-Li Qin, Xing Lu, Ke Wang, Sirong Pan, Feng-Wei Xu, Enrique Vazquez-Semadeni, Shanghuo Li, Gilberto C. Gomez, Aina Palau, Guido Garay, Paul F. Goldsmith, Mika Juvela, Anindya Saha, Leonardo Bronfman, Chang Won Lee, Kenichi Tatematsu, Lokesh Dewangan, Jianwen Zhou, Yong Zhang, Amelia Stutz, Chakali Eswaraiah, L. Viktor Toth, Isabelle Ristorcelli, Xianjin Shen, Anxu Luo, James O. Chibueze
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.10332
Pdf link: https://arxiv.org/pdf/2306.10332
Abstract
There is growing evidence that high-mass star formation and hub-filament systems (HFS) are intricately linked. The gas kinematics along the filaments and the forming high-mass star(s) in the central hub are in excellent agreement with the new generation of global hierarchical high-mass star formation models. In this paper, we present an observational investigation of a typical HFS cloud, G310.142+0.758 (G310 hereafter) which reveals unambiguous evidence of mass inflow from the cloud scale via the filaments onto the forming protostar(s) at the hub conforming with the model predictions. Continuum and molecular line data from the ATOMS and MALT90 surveys are used that cover different spatial scales. Three filaments (with total mass $5.7\pm1.1\times 10^3~~M_{\odot}$) are identified converging toward the central hub region where several signposts of high-mass star formation have been observed. The hub region contains a massive clump ($1280\pm260~~M_{\odot}$) harbouring a central massive core. Additionally, five outflow lobes are associated with the central massive core implying a forming cluster. The observed large-scale, smooth and coherent velocity gradients from the cloud down to the core scale, and the signatures of infall motion seen in the central massive clump and core, clearly unveil a nearly-continuous, multi-scale mass accretion/transfer process at a similar mass infall rate of $\sim 10^{-3}~M_{\odot}~yr^{-1}$ over all scales, feeding the central forming high-mass protostar(s) in the G310 HFS cloud.

Analytical modelling of adaptive optics systems: Role of the influence function

Authors: Anthony Berdeu (LESIA), Michel Tallon (CRAL), Éric Thiébaut (CRAL), Maud Langlois (CRAL)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.10803
Pdf link: https://arxiv.org/pdf/2306.10803
Abstract
Context. Adaptive optics (AO) is now a tool commonly deployed in astronomy. The real time correction of the atmospheric turbulence that AO enables allows telescopes to perform close to the diffraction limit at the core of their point spread function (PSF). Among other factors, AO-corrected PSFs depend on the ability of the wavefront corrector (WFC), generally a deformable mirror, to fit the incident wavefront corrugations. Aims. In this work, we focus on this error introduced by the WFC, the so-called fitting error. To date, analytical models only depend on the WFC cut-off frequency, and Monte Carlo simulations are the only solution for studying the impact of the WFC influence function shape on the AO-corrected PSF. We aim to develop an analytical model accounting for the influence function shape. Methods. We first obtain a general analytical model of the fitting error structure function. With additional hypotheses, we then derive an analytical model of the AO-corrected power spectral density. These two analytical solutions are compared with Monte Carlo simulations on different ideal profiles (piston, pyramid, Gaussian) as well as with real hardware (DM192 from ALPAO). Results. Our analytical predictions show a very good agreement with the Monte Carlo simulations. We show that in the image plane, the depth of the correction as well as the transition profile between the AO-corrected area and the remaining turbulent halo depend on the influence functions of the WFC. We also show that the generally assumed hypothesis of stationarity of the AO correction is actually not met. Conclusions. As the fitting error is the intrinsic optimal limit of an AO system, our analytical model allows for the assessment of the theoretical limits of extreme AO systems limited by the WFC in high-contrast imaging through a context where other errors become comparable.

A re-analysis of equilibrium chemistry in five hot Jupiters

Authors: Emilie Panek, Jean-Philippe Beaulieu, Pierre Drossart, Olivia Venot, Quentin Changeat, Ahmed Al-Refaie, Amélie Gressier
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.10873
Pdf link: https://arxiv.org/pdf/2306.10873
Abstract
Studying chemistry and chemical composition is fundamental to go back to formation history of planetary systems. We propose here to have another look at five targets to better determine their composition and the chemical mechanisms that take place in their atmospheres. We present a re-analysis of five Hot Jupiters, combining multiple instruments and using Bayesian retrieval methods. We compare different combinations of molecules present in the simulated atmosphere, different chemistry types as well as different clouds parametrization. As a consequence of recent studies questioning the detection of Na and K in the atmosphere of HD 209458b as being potentially contaminated by stellar lines when present, we study the impact on other retrieval parameters of misinterpreting the presence of these alkali species. We use spatially scanned observations from the grisms G102 and G141 of the WFC3 on HST, with a wavelength coverage of $\sim$0.8 to $\sim$1.7 microns. We analyse these data with the publicly available Iraclis pipeline. We added to our datasets STIS observations to increase our wavelength coverage from $\sim$0.4 to $\sim$1.7 microns. We then performed a Bayesian retrieval analysis with the open-source TauREx using a nested sampling algorithm. We explore the influence of including Na and K on the retrieval of the molecules from the atmosphere. Our data re-analysis and Bayesian retrieval are consistent with previous studies but we find small differences in the retrieved parameters. After all, Na and K has no significant impact on the properties of the planet atmospheres. Therefore, we present here our new best-fit models, taking into account molecular abundances varying freely and equilibrium chemistry. This work is a preparation for a future addition of more sophisticated representation of chemistry taking into account disequilibrium effects such as vertical mixing and photochemistry.

Dense Molecular Environments of B[e] Supergiants and Yellow Hypergiants

Authors: Michaela Kraus, Michalis Kourniotis, Maria Laura Arias, Andrea F. Torres, Dieter H. Nickeler
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.10911
Pdf link: https://arxiv.org/pdf/2306.10911
Abstract
Massive stars expel large amounts of mass during their late evolutionary phases. We aim to unveil the physical conditions within the warm molecular environments of B[e] supergiants (B[e]SGs) and yellow hypergiants (YHGs), which are known to be embedded in circumstellar shells and disks. We present K-band spectra of two B[e]SGs from the Large Magellanic Cloud and four Galactic YHGs. The CO band emission detected from the B[e]SGs LHA 120-S 12 and LHA 120-S 134 suggests that these stars are surrounded by stable rotating molecular rings. The spectra of the YHGs display a rather diverse appearance. The objects 6 Cas and V509 Cas lack any molecular features. The star [FMR2006] 15 displays blue-shifted CO bands in emission, which might be explained by a possible close to pole-on oriented bipolar outflow. In contrast, HD 179821 shows blue-shifted CO bands in absorption. While the star itself is too hot to form molecules in its outer atmosphere, we propose that it might have experienced a recent outburst. We speculate that we currently can only see the approaching part of the expelled matter because the star itself might still block the receding parts of a (possibly) expanding gas shell.

The effect of tidal forces on the Jeans instability criterion in star-forming regions

Authors: Rafael Zavala-Molina, Javier Ballesteros-Paredes, Adriana Gazol, Aina Palau
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
Arxiv link: https://arxiv.org/abs/2306.11106
Pdf link: https://arxiv.org/pdf/2306.11106
Abstract
Recent works have proposed the idea of a tidal screening scenario, in which tidal forces determine the mass that a protostar can accrete to explain the IMF. In this scenario, gravitationally unstable fragments will compete for the gas reservoir in a star-forming clump. In this contribution, we propose to properly include the action of an external gravitational potential in the Jeans linear instability analysis as previously proposed by Jog. We have found that an external gravitational potential can reduce the critical mass required for the perturbation to collapse if the tidal force produced is compressive or increase it if it is disruptive. Our analytical treatment provides (a) new mass and length collapse conditions; (b) a simple equation for observers to check whether their observed fragments can collapse; and (c) a simple equation to compute whether collapse-induced turbulence can produce the levels of observed fragmentation. Our results suggest that, given envelopes with similar mass and density, the flatter ones should produce more stars than the steeper ones. If the density profile is a power-law, the corresponding power-law index separating these two regimes should be about 1.5. We finally applied our formalism to 160 fragments identified within 18 massive star-forming cores of previous works. We found that considering tides, 49% of the sample may be gravitationally unstable and that it is unlikely that turbulence acting at the moment of collapse has produced the fragmentation of these cores. Instead, these fragments should have formed earlier when the parent core was substantially flatter.

Oort cloud (exo)planets

Authors: Sean N. Raymond, Andre Izidoro, Nathan A. Kaib
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
Arxiv link: https://arxiv.org/abs/2306.11109
Pdf link: https://arxiv.org/pdf/2306.11109
Abstract
Dynamical instabilities among giant planets are thought to be nearly ubiquitous, and culminate in the ejection of one or more planets into interstellar space. Here we perform N-body simulations of dynamical instabilities while accounting for torques from the galactic tidal field. We find that a fraction of planets that would otherwise have been ejected are instead trapped on very wide orbits analogous to those of Oort cloud comets. The fraction of ejected planets that are trapped ranges from 1-10%, depending on the initial planetary mass distribution. The local galactic density has a modest effect on the trapping efficiency and the orbital radii of trapped planets. The majority of Oort cloud planets survive for Gyr timescales. Taking into account the demographics of exoplanets, we estimate that one in every 200-3000 stars could host an Oort cloud planet. This value is likely an overestimate, as we do not account for instabilities that take place at early enough times to be affected by their host stars' birth cluster, or planet stripping from passing stars. If the Solar System's dynamical instability happened after birth cluster dissolution, there is a ~7% chance that an ice giant was captured in the Sun's Oort cloud.

A labeled dataset of cloud types using data from GOES-16 and CloudSat

Authors: Paula V. Romero Jure, Sergio Masuelli, Juan Bautista Cabral
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Computer Vision and Pattern Recognition (cs.CV); Machine Learning (cs.LG); Atmospheric and Oceanic Physics (physics.ao-ph)
Arxiv link: https://arxiv.org/abs/2306.11159
Pdf link: https://arxiv.org/pdf/2306.11159
Abstract
In this paper we present the development of a dataset consisting of 91 Multi-band Cloud and Moisture Product Full-Disk (MCMIPF) from the Advanced Baseline Imager (ABI) on board GOES-16 geostationary satellite with 91 temporally and spatially corresponding CLDCLASS products from the CloudSat polar satellite. The products are diurnal, corresponding to the months of January and February 2019 and were chosen such that the products from both satellites can be co-located over South America. The CLDCLASS product provides the cloud type observed for each of the orbit's steps and the GOES-16 multiband images contain pixels that can be co-located with these data. We develop an algorithm that returns a product in the form of a table that provides pixels from multiband images labelled with the type of cloud observed in them. These labelled data conformed in this particular structure are very useful to perform supervised learning. This was corroborated by training a simple linear artificial neural network based on the work of Gorooh et al. (2020), which gave good results, especially for the classification of deep convective clouds.

On the Evolution of, and Hot Gas in, Wind-Blown Bubbles around Massive Stars -- Wind Bubbles Are Not Energy-Conserving

Authors: Vikram V. Dwarkadas (University of Chicago)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.11192
Pdf link: https://arxiv.org/pdf/2306.11192
Abstract
The structure and evolution of wind-blown bubbles (WBBs) around massive stars has primarily been investigated using an energy-conserving model of wind-blown bubbles. While this model is useful in explaining the general properties of the evolution, several problems remain, including inconsistencies between observed wind luminosities and those derived using this formulation. Major difficulties include the low X-ray temperature and X-ray luminosity, compared to the model. In this paper, we re-examine the evolution, dynamics, and kinematics of WBBs around massive stars, using published ionization gasdynamic simulations of wind-blown bubbles. We show that WBBs can cool efficiently due to the presence of various instabilities and turbulence within the bubble. The expansion of WBBs is more consistent with a momentum-conserving solution, rather than an energy-conserving solution. This compares well with the dynamics and kinematics of observed wind bubbles. Despite the cooling of the bubble, the shocked wind temperature is not reduced to the observed values. We argue that the X-ray emission arise mainly from clumps and filaments within the hot shocked wind region, with temperatures just above 10$^6$ K. The remainder of the plasma can contribute to a lesser extent.

Exoplanet Interior Retrievals: core masses and metallicities from atmospheric abundances

Authors: Sanne Bloot, Yamila Miguel, Michaël Bazot, Saburo Howard
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.11354
Pdf link: https://arxiv.org/pdf/2306.11354
Abstract
The mass and distribution of metals in the interiors of exoplanets are essential for constraining their formation and evolution processes. Nevertheless, with only masses and radii measured, the determination of exoplanet interior structures is degenerate, and so far simplified assumptions have mostly been used to derive planetary metallicities. In this work, we present a method based on a state-of-the-art interior code, recently used for Jupiter, and a Bayesian framework, to explore the possibility of retrieving the interior structure of exoplanets. We use masses, radii, equilibrium temperatures, and measured atmospheric metallicities to retrieve planetary bulk metallicities and core masses. Following results on the giant planets in the solar system and recent development in planet formation, we implement two interior structure models: one with a homogeneous envelope and one with an inhomogeneous one. Our method is first evaluated using a test planet and then applied to a sample of 37 giant exoplanets with observed atmospheric metallicities from the pre-JWST era. Although neither internal structure model is preferred with the current data, it is possible to obtain information on the interior properties of the planets, such as the core mass, through atmospheric measurements in both cases. We present updated metal mass fractions, in agreement with recent results on giant planets in the solar system.

The $γ$-process nucleosynthesis in core-collapse supernovae. I. A novel analysis of $γ$-process yields in massive stars

Authors: L. Roberti, M. Pignatari, A. Psaltis, A. Sieverding, P. Mohr, Zs. Fülöp, M. Lugaro
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2306.11409
Pdf link: https://arxiv.org/pdf/2306.11409
Abstract
The $\gamma$-process nucleosynthesis in core-collapse supernovae is generally accepted as a feasible process for the synthesis of neutron-deficient isotopes beyond iron. However, crucial discrepancies between theory and observations still exist: the average production of $\gamma$-process yields from massive stars are too low to reproduce the solar distribution in galactic chemical evolution calculations, and the yields of the Mo and Ru isotopes are by a further factor of 10 lower than the yields of the other $\gamma$-process nuclei. We investigate the $\gamma$-process in 5 sets of core-collapse supernova models published in literature with initial masses 15, 20, and 25 M$_{\odot}$ at solar metallicity. We compared the $\gamma$-process overproduction factors from the different models. To highlight the possible effect of nuclear physics input, we also considered 23 ratios of two isotopes close to each other in mass, relative to their solar values. Further, we investigated the contribution of C-O shell mergers in the supernova progenitors as an additional site of the $\gamma$-process. Our analysis shows that a large scatter among the different models exists for both the $\gamma$-process integrated yields and the isotopic ratios. We found only 10 ratios that agree with their solar values, all the others differ by at least a factor of 3 from the solar values in all the considered sets of models. The $\gamma$-process within C-O shell mergers mostly influence the isotopic ratios that involve intermediate and heavy proton-rich isotopes with $\rm A>100$.

Planetesimal formation at the gas pressure bump following a migrating planet II. Effects of dust growth

Authors: Yuhito Shibaike, Yann Alibert
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.11619
Pdf link: https://arxiv.org/pdf/2306.11619
Abstract
Planetesimal formation is still mysterious. One of the ways to form planetesimals is to invoke a gas pressure bump in a protoplanetary disc. In our previous paper, we propose a new scenario in which the piled-up dust at a gas pressure bump created by a migrating planet form planetesimals by streaming instability in a wide region of the disc as the planet migrates inward. In this work, we consider the global time evolution of dust and investigate the detailed conditions and results of the planetesimal formation in our scenario. We use a 1D grid single-sized dust evolution model, which can follow the growth of the particles by their mutual collision and their radial drift and diffusion. We calculate the time-evolution of the radial distribution of the peak mass and surface density of the dust in a gas disc perturbed by an embedded migrating planet and investigate if the dust satisfies the condition for planetesimal formation. We find that planetesimals form in a belt-like region between the snowline and the position where the planet reaches its pebble-isolation mass when the strength of turbulence is $10^{-4}\leq\alpha\leq10^{-3}$, which is broadly consistent with observed value. The mechanism of the formation, streaming instability or mutual collision, depends on the timescale of the streaming instability. The total mass of planetesimals also depends on $\alpha$ and is about $30-100~M_{\rm E}$ if the planetary core has already existed at the beginning and grows by gas accretion, but it decreases as the timing of the formation of the planetary core is later. We also provide simple approximate expressions of the surface density and total mass of the planetesimals and find that the total mass strongly depends on the dust mass. We show that planetesimals form in a belt-like region by the combination of the dust pile-up at the gas pressure bump formed by a planet and its inward migration.

Neural Astrophysical Wind Models

Authors: Dustin D. Nguyen
Subjects: Astrophysics of Galaxies (astro-ph.GA); Machine Learning (cs.LG); Data Analysis, Statistics and Probability (physics.data-an); Fluid Dynamics (physics.flu-dyn)
Arxiv link: https://arxiv.org/abs/2306.11666
Pdf link: https://arxiv.org/pdf/2306.11666
Abstract
The bulk kinematics and thermodynamics of hot supernovae-driven galactic winds is critically dependent on both the amount of swept up cool clouds and non-spherical collimated flow geometry. However, accurately parameterizing these physics is difficult because their functional forms are often unknown, and because the coupled non-linear flow equations contain singularities. We show that deep neural networks embedded as individual terms in the governing coupled ordinary differential equations (ODEs) can robustly discover both of these physics, without any prior knowledge of the true function structure, as a supervised learning task. We optimize a loss function based on the Mach number, rather than the explicitly solved-for 3 conserved variables, and apply a penalty term towards near-diverging solutions. The same neural network architecture is used for learning both the hidden mass-loading and surface area expansion rates. This work further highlights the feasibility of neural ODEs as a promising discovery tool with mechanistic interpretability for non-linear inverse problems.

by olozhika (Xing Yuchen).

2023-06-21

New submissions for Fri, 2 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 8papers

Diffuse Ultra-High-Energy Gamma-Ray Emission From TeV Halos

Authors: Ariane Dekker, Ian Holst, Dan Hooper, Giovani Leone, Emily Simon, Huangyu Xiao
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2306.00051
Pdf link: https://arxiv.org/pdf/2306.00051
Abstract
The LHAASO Collaboration has recently reported a measurement of the diffuse gamma-ray emission from the Galactic Plane at energies between 10 TeV and 1 PeV. While this emission is brighter than that expected from cosmic-ray interactions in the interstellar medium alone, we show that the intensity, spectrum, and morphology of this excess are in good agreement with that predicted from the "TeV halos" which surround the Milky Way's pulsar population. These results support the conclusion that TeV halos dominate the ultra-high-energy sky, and that these objects convert $\sim 5%$ of their total spindown power into very-high and ultra-high-energy photons.

Broadband VLA Spectral Line Survey of a Sample of Ionized Jet Candidates

Authors: E. Sanchez-Tovar (1), E. D. Araya (1,2), V. Rosero (3), P. Hofner (2,3), S. Kurtz (4) ((1) Physics Department, Western Illinois University, Macomb, IL, USA, (2) New Mexico Institute of Mining and Technology, Physics Department, Socorro, NM, USA, (3) National Radio Astronomy Observatory, Socorro, NM, USA, (4) Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antig. Carr. a Pátzcuaro 8701, 58089, Morelia, Michoacán, México.)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.00111
Pdf link: https://arxiv.org/pdf/2306.00111
Abstract
The study of the interaction between ionized jets, molecular outflows and their environments is critical to understanding high-mass star formation, especially because jets and outflows are thought to be key in the transfer of angular momentum outwards from accretion disks. We report a low-spectral resolution VLA survey for hydrogen radio recombination lines, OH, NH$_3$, and CH$_3$OH lines toward a sample of 58 high-mass star forming regions that contain numerous ionized jet candidates. The observations are from a survey designed to detect radio continuum; the novel aspect of this work is to search for spectral lines in broadband VLA data (we provide the script developed in this work to facilitate exploration of other datasets). We report detection of 25$,$GHz CH$_3$OH transitions toward ten sources; five of them also show NH$_3$ emission. We found that most of the sources detected in CH$_3$OH and NH$_3$ have been classified as ionized jets or jet candidates and that the emission lines are coincident with, or very near ($\lesssim 0.1$ pc) these sources, hence, these molecular lines could be used as probes of the environment near the launching site of jets/outflows. No radio recombination lines were detected, but we found that the RMS noise of stacked spectra decreases following the radiometer equation. Therefore, detecting radio recombination lines in a sample of brighter free-free continuum sources should be possible. This work demonstrates the potential of broadband VLA continuum observations as low-resolution spectral line scans.

Humid Evolution of Haze in the Atmosphere of Super-Earths in the Habitable Zone

Authors: Julien Maillard, Nathalie Carrasco, Christopher P. Rüger, Audrey Chatain, Isabelle Schmitz-Afonso, Chad R. Weisbrod, Laetitia Bailly, Emilie Petit, Thomas Gautier, Amy M. McKenna, Carlos Afonso
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.00276
Pdf link: https://arxiv.org/pdf/2306.00276
Abstract
Photochemical hazes are expected to form and significantly contribute to the chemical and radiative balance of exoplanets with relatively moderate temperatures, possibly in the habitable zone of their host star. In the presence of humidity, haze particles might thus serve as cloud condensation nuclei and trigger the formation of water droplets. In the present work, we are interested in the chemical impact of such a close interaction between photochemical hazes and humidity on the organic content composing the hazes and on the capacity to generate organic molecules with high prebiotic potential. For this purpose, we explore experimentally the sweet spot by combining N-dominated super-Earth exoplanets in agreement with Titan's rich organic photochemistry and humid conditions expected for exoplanets in habitable zones. A logarithmic increase with time is observed for the relative abundance of oxygenated species, with O-containing molecules dominating after 1 month only. The rapidity of the process suggests that the humid evolution of N-rich organic haze provides an efficient source of molecules with high prebiotic potential.

The evolutionary stage of Betelgeuse inferred from its pulsation periods

Authors: Hideyuki Saio, Devesh Nandal, Georges Meynet, Sylvia Ekstöm
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.00287
Pdf link: https://arxiv.org/pdf/2306.00287
Abstract
Betelgeuse is a well known bright red supergiant that shows semi-regular variations with four approximate periods of 2200, 420, 230, and 185 days. While the longest period was customarily regarded as LSP (long secondary period) of unknown origin, we identify the 2200-d period as the radial fundamental mode, and the three shorter periods as the radial first, second, and third overtones. From a nonadiabatic pulsation analysis including the pulsation/convection coupling, we have found that these radial pulsation modes are all excited in the envelope of a model in a late stage of the core-carbon burning. Models with similar pulsation property have masses around 11M_\odot (19M_\odot at ZAMS) with luminosities (log L/L_\odot =5.275.28) and effective temperatures (log T_{eff}\approx 3.53) that are consistent with the range of the observational determinations. We also find that a synthetic light curve obtained by adding the fundamental and the first-overtone mode qualitatively agrees with the light curve of Betelgeuse up to the Great Dimming. We conclude that Betelgeuse is in the late stage of core carbon burning, and a good candidate for the next Galactic supernova.

A matched-filter approach to radio variability and transients: searching for orphan afterglows in the VAST Pilot Survey

Authors: James K. Leung, Tara Murphy, Emil Lenc, Philip G. Edwards, Giancarlo Ghirlanda, David L. Kaplan, Andrew O'Brien, Ziteng Wang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.00447
Pdf link: https://arxiv.org/pdf/2306.00447
Abstract
Radio transient searches using traditional variability metrics struggle to recover sources whose evolution timescale is significantly longer than the survey cadence. Motivated by the recent observations of slowly evolving radio afterglows at gigahertz frequency, we present the results of a search for radio variables and transients using an alternative matched-filter approach. We designed our matched-filter to recover sources with radio light curves that have a high-significance fit to power-law and smoothly broken power-law functions; light curves following these functions are characteristic of synchrotron transients, including "orphan" gamma-ray burst afterglows, which were the primary targets of our search. Applying this matched-filter approach to data from Variables and Slow Transients Pilot Survey conducted using the Australian SKA Pathfinder, we produced five candidates in our search. Subsequent Australia Telescope Compact Array observations and analysis revealed that: one is likely a synchrotron transient; one is likely a flaring active galactic nucleus, exhibiting a flat-to-steep spectral transition over $4,$months; one is associated with a starburst galaxy, with the radio emission originating from either star formation or an underlying slowly-evolving transient; and the remaining two are likely extrinsic variables caused by interstellar scintillation. The synchrotron transient, VAST J175036.1$-$181454, has a multi-frequency light curve, peak spectral luminosity and volumetric rate that is consistent with both an off-axis afterglow and an off-axis tidal disruption event; interpreted as an off-axis afterglow would imply an average inverse beaming factor $\langle f^{-1}{\text{b}} \rangle = 860^{+1980}{-710}$, or equivalently, an average jet opening angle of $\langle \theta_{\textrm{j}} \rangle = 3^{+4}_{-1},$deg.

Gravitational Wave Detection by Hollow-Core Fiber-Optics Mach-Zehnder Interferometry

Authors: Francesco De Martini
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
Arxiv link: https://arxiv.org/abs/2306.00472
Pdf link: https://arxiv.org/pdf/2306.00472
Abstract
Recent advances in the field of very long distance optical communication suggest the adoption of the advanced technology based on Hollow Core Nested Anti-resonant Nodeless Fiber (HC-NANF) within the endeavour of Gravitational Wave detection using a Mach-Zehnder optical interferometer (MZ-IF). The proposal, consisting of a summary project of the device emphasizes the favorable properties of (MZ-IF) in comparison with Michelson Interferometer (MIF) currently in operation. The key feature of the proposed method consists of the use of a couple of "fibrated" metallic antennas enfolded by a very large (K x 8.10^4 with K=1,2,3 etc.) of coiled (HC-NANF) rings. This amounts to a corresponding fiber length: Leff = K x 1600 Km. The relevant properties of the device are noise reduction, absence of critical optical mirror alignment in a noisy environment, reduced spatial extension of the apparatus, exploration of the entire sky scenario by freely orientable antennas, a substational cost reduction of the apparatus. The remarkable properties of (HC-NANF), invented by F. Poletti in 2013 are currently investigated by his group at the University of Southampton (UK).

Long-term optical spectral monitoring of a changing-look active galactic nucleus NGC 3516 -- II. Broad-line profile variability

Authors: Luka C. Popović, Dragana Ilić, Alexander Burenkov, Victor Manuel Patiño Álvarez, Sladjana Marceta-Mandić, Jelena Kovacević - Dojcinović, Elena Shablovinskaya, Andjelka B. Kovacević, Paola Marziani, Vahram Chavushyan, Jian-Min Wang, Yan-Rong Li, Evencio G. Mediavilla
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.00669
Pdf link: https://arxiv.org/pdf/2306.00669
Abstract
We analyze the broad H$\beta$ line profile variability of the "changing look" active galactic nucleus (CL-AGN) NGC 3516 over a long period of 25 years. The observed change in the broad line profile may indicate a change in the geometry of the broad line region (BLR). Using spectral line profiles, we aim to explore changes in the kinematics and dimensions of the BLR in NGC 3516. We consider two possible scenarios, i.e. changes in the broad-line emission are caused by a decrease of ionization continuum emission or by the BLR obscuration by outer dusty regions. With this investigation we aim to clarify the CL mechanism of this AGN. We analyze the spectral band around the H$\beta$ line as well as the broad H$\beta$ line parameters, and how they change in time. We model the broad-line profiles assuming that there is an emission from the accretion disc superposed with an emission from a surrounding region that is outside the disc. We find that in the Type 1 activity phase, the BLR is very complex. There is a clear disc-like BLR that contributes to the broad line wings and an additional intermediate line region (ILR) that contributes to the line core. In the high activity phase, the ILR emission is close to the center of the line (in some cases slightly shifted to the red), whereas in the low activity phase (i.e., Type 2 phase), the ILR component has a significant shift to the blue, indicating an outflow. We propose that the changing look mechanism in NGC 3516 is rather connected with the intrinsic effects than with an outer obscuring region. It may still be possible that the dust has an important role in the low activity phase when it is coming inside of the BLR, making a dusty BLR. In this way, it causes a decrease in the ionization and recombination rates.

One hundred new unidentified optical emission lines from a low-metallicity photodissociation region

Authors: William J. Henney (IRyA-UNAM, Morelia, Mexico), Mabel Valerdi (INAOE, Puebla, Mexico)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.00894
Pdf link: https://arxiv.org/pdf/2306.00894
Abstract
We report the detection of a rich spectrum of more than one hundred optical emission lines from neutral/molecular gas in the photodissociation region (PDR) around the mini-starburst cluster NGC 346 in the Small Magellanic Cloud. We propose the term Deep Red Line (DRL) for these lines, which are concentrated in the spectral range 6000 Angstrom to 9300 Angstrom and have observed brightnesses ranging from 0.01% to 0.4% times that of the H beta lambda 4861 hydrogen recombination line. The vast majority of the DRLs have never previously been detected from astronomical nebulae. Some of them may be due to neutral atoms, but most have no credible identifications in databases of atomic line transitions, and it is possible that some may correspond to transitions in molecules or molecular ions. Analysis of the spatial distribution of the DRLs shows that they originate from a range of depths in the PDR, providing a missing link between the shallow layers probed by known fluorescent lines of neutral nitrogen and oxygen, and the more shielded layers probed by neutral carbon recombination lines. Comparison with other PDRs shows that the relative strength of the DRLs with respect to the [C I] lambda 8727 line increases rapidly with decreasing metallicity.

by olozhika (Xing Yuchen).

2023-06-02

New submissions for Tue, 27 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 7papers

Chemical Conditions on Hycean Worlds

Authors: Nikku Madhusudhan, Julianne I. Moses, Frances Rigby, Edouard Barrier
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.13706
Pdf link: https://arxiv.org/pdf/2306.13706
Abstract
Traditionally, the search for life on exoplanets has been predominantly focused on rocky exoplanets. Hycean worlds are a class of habitable sub-Neptunes with planet-wide oceans and H2-rich atmospheres. Their broad range of possible sizes and temperatures lead to a wide habitable zone and high potential for discovery and atmospheric characterization using transit spectroscopy. Over a dozen candidate Hycean planets are already known to be transiting nearby M dwarfs, making them promising targets for atmospheric characterization with the James Webb Space Telescope (JWST). In this work, we investigate possible chemical conditions on a canonical Hycean world, focusing on (a) the present and primordial molecular composition of the atmosphere, and (b) the inventory of bioessential elements for the origin and sustenance of life in the ocean. Based on photochemical and kinetic modeling for a range of conditions, we discuss the possible chemical evolution and observable present-day composition of its atmosphere. In particular, for reduced primordial conditions the early atmospheric evolution passes through a phase that is rich in organic molecules that could provide important feedstock for prebiotic chemistry. We investigate avenues for delivering bioessential metals to the ocean, considering the challenging lack of weathering from a rocky surface and the ocean separated from the rocky core by a thick icy mantle. Based on ocean depths from internal structure modelling and elemental estimates for the early Earth's oceans, we estimate the requirements for bioessential metals in such a planet. We find that the requirements can be met for plausible assumptions about impact history and atmospheric sedimentation, and supplemented by other steady state sources. We discuss the observational prospects for atmospheric characterisation of Hycean worlds.

Neutrino-Driven Winds in Three-Dimensional Core-Collapse Supernova Simulations

Authors: Tianshu Wang, Adam Burrows
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.13712
Pdf link: https://arxiv.org/pdf/2306.13712
Abstract
In this paper, we analyze the neutrino-driven winds that emerge in twelve unprecedentedly long-duration 3D core-collapse supernova simulations done using the code Fornax. The twelve models cover progenitors with ZAMS mass between 9 and 60 solar masses. In all our models, we see transonic outflows that are at least two times as fast as the surrounding ejecta and that originate generically from a PNS surface atmosphere that is turbulent and rotating. We find that winds are common features of 3D simulations, even if there is anisotropic early fallback. We find that the basic dynamical properties of 3D winds behave qualitatively similarly to those inferred in the past using simpler 1D models, but that the shape of the emergent wind can be deformed, very aspherical, and channeled by its environment. The thermal properties of winds for less massive progenitors very approximately recapitulate the 1D stationary solutions, while for more massive progenitors they deviate significantly due to aspherical fallback. The $Y_e$ temporal evolution in winds is stochastic, and there can be some neutron-rich phases. Though no strong r-process is seen in any model, a weak r-process can be produced and isotopes up to $^{90}$Zr are synthesized in some models. Finally, we find that there is at most a few percent of a solar mass in the integrated wind component, while the energy carried by the wind itself can be as much as 10-20% of the total explosion energy.

Luminous Radio Emission from the Superluminous Supernova 2017ens at 3.3 years after explosion

Authors: Raffaella Margutti, J. S. Bright, D. J. Matthews, D. L. Coppejans, K. D. Alexander, E. Berger, M. Bietenholz, R. Chornock, L. DeMarchi, M. R. Drout, T. Eftekhari, W. V. Jacobson-Galan, T. Laskar, D. Milisavljevic, K. Murase, M. Nicholl, C. M. B. Omand, M. Stroh, G. Terreran, A. Z. VanderLey
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.13730
Pdf link: https://arxiv.org/pdf/2306.13730
Abstract
We present the results from a multi-year radio campaign of the superluminous supernova (SLSN) 2017ens, which yielded the earliest radio detection of a SLSN to date at the age of $\sim$3.3 years after explosion. SN2017ens was not detected at radio frequencies in the first $\sim$300,d of evolution but reached $L_{\nu}\approx 10^{28},\rm{erg,s^{-1},cm^{-2}}$ at $\nu\sim 6$ GHz, $\sim1250$ days post-explosion. Interpreting the radio observations in the context of synchrotron radiation from the supernova shock interaction with the circumstellar medium (CSM), we infer an effective mass-loss rate of $\approx 10^{-4},\rm{M_{\odot}yr^{-1}}$ at $r\sim 10^{17}$ cm from the explosion's site, for a wind speed of $v_w=50-60,\rm{km,s^{-1}}$ measured from optical spectra. These findings are consistent with the spectroscopic metamorphosis of SN2017ens from hydrogen-poor to hydrogen-rich $\sim190$ d after explosion reported by Chen et al., 2018. SN2017ens is thus an addition to the sample of hydrogen-poor massive progenitors that explode shortly after having lost their hydrogen envelope. The inferred circumstellar densities, implying a CSM mass up to $\sim0.5,\rm{M_{\odot}}$, and low velocity of the ejection point at binary interactions (in the form of common envelope evolution and subsequent envelope ejection) playing a role in shaping the evolution of the stellar progenitors of SLSNe in the $\lesssim 500$ yr preceding core collapse.

Probing the origin of the two-component structure of broad line region by reverberation mapping of an extremely variable quasar

Authors: Shumpei Nagoshi, Fumihide Iwamuro, Satoshi Yamada, Yoshihiro Ueda, Yuto Oikawa, Masaaki Otsuka, Keisuke Isogai, Shin Mineshige
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.13930
Pdf link: https://arxiv.org/pdf/2306.13930
Abstract
The physical origins of components in the unified model of quasars such as broad line region (BLR), dust torus, and narrow line region are unresolved. To learn more about them, we focus on studying Changing-State Quasars (also known as Changing-Look Quasars) as they offer the opportunity to observe structural changes associated with state transitions. This can give us insight into the origins of each quasar structure. We aimed to understand the central core structure of one of the most variable Changing-State Quasars, SDSS J125809.31+351943.0, and how it changes before and after the state transition. We performed reverberation mapping with optical spectroscopy to investigate the structure of the BLR and to measure the black hole mass. The results of the reverberation mapping show that the Eddington ratio crossed the value of 0.01 before and after state transition for the black hole mass of $10^{9.46^{+0.15}{-0.19}}\rm{M\odot}$. In addition, we compared optical to X-ray spectral indices ($\alpha_{\rm{ox}}$) before and after the state transition to investigate the structure difference of the accretion disk. These variations in $\alpha_{\rm{ox}}$ and the Eddington ratio were found to behave similarly to the state transition seen in X-ray binary systems. We also measured the time-lag between the mid-IR and the optical light curve to estimate the size of the dust torus. From all the acquired information about the BLR and dust torus, we confirmed the existence of two distinct rotating/inflowing BLR components located near the dust torus, probably generated by different processes, which are the origins of the BLRs.

Interacting Supernova Remnants: a population model for the Cherenkov Telescope Array

Authors: Crestan Silvia
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.14359
Pdf link: https://arxiv.org/pdf/2306.14359
Abstract
The work presented in this thesis is focused on the interacting supernova remnants (iSNRs), a class of gamma-ray emitting SNR where the radiation arise from the interaction of the SNR with a massive molecular cloud. At the moment only 16 iSNR are known. Before this work, there was not any population study of these sources. Here is proposed a model for the Galactic population of iSNRs which can be used in order to predict the number of these systems in the Galaxy and how many of these will be detectable by the next generation of {\gamma}-ray instruments. iSNRs are of particular interest for the particle acceleration study because these objects have been proved to be sites of acceleration of protons up to high energies. Furthermore, high-energy $\gamma$-ray emission can pinpoint the presence of energetic leptons or ions and help to constraint the acceleration efficiency and maximum energy of accelerated particles The model presented her was only achievable through the creation of a complete catalog of {\gamma}-ray (both GeV and TeV) supernova remnants that for each supernova remnants gives collect the physical and spectral information available in litterature. Simulating and analyzing the synthetic population, it was found that the Cherenkov Telescope Array (CTA) will be able to duplicate the number of detected interacting systems in its survey of the Galactic plane.

A Transiting Super-Earth in the Radius Valley and An Outer Planet Candidate Around HD 307842

Authors: Xinyan Hua, Sharon Xuesong Wang, Johanna K. Teske, Tianjun Gan, Avi Shporer, George Zhou, Keivan G. Stassun, Markus Rabus, Steve B. Howell, Carl Ziegler, Jack J. Lissauer, Joshua N. Winn, Jon M. Jenkins, Eric B. Ting, Karen A. Collins, Andrew W. Mann, Wei Zhu, Su Wang, R. Paul Butler, Jeffrey D. Crane, Stephen A. Shectman, Luke G. Bouma, Cesar Briceno, Diana Dragomir, William Fong, Nicholas Law, Jennifer V. Medina, Samuel N. Quinn, George R. Ricker, Richard P. Schwarz, Sara Seager, Ramotholo Sefako, Chris Stockdale, Roland Vanderspek, Joel Villasenor
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.14655
Pdf link: https://arxiv.org/pdf/2306.14655
Abstract
We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) measurements constrain the mass to be 9.67+0.83/-0.82 [Earth Masses]. We also report the discovery of an additional planet candidate on an outer orbit that is most likely non-transiting. The possible periods of the planet candidate are approximately 20 to 63 days, with the corresponding RV semi-amplitudes expected to range from 3.2 to 5.4 m/s and minimum masses from 12.6 to 31.1 [Earth Masses]. The radius of the transiting planet (planet b) is 1.93+0.11/-0.09 [Earth Radii], which results in a mean density of 7.4+1.4/-1.2 g/cm^3 suggesting that TOI-784b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784b is located at the lower edge of the so-called ``radius valley'' in the radius vs. insolation plane, which is consistent with the photoevaporation or core-powered mass loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60+0.84/-0.86 degrees and <= 88.3-89.2 degrees, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

ALMA-IMF VII -- First release of the full spectral line cubes:Core kinematics traced by DCN J=(3-2)

Authors: N. Cunningham, A. Ginsburg, R. Galván-Madrid, F. Motte, T. Csengeri, A. M. Stutz, M. Fernández-López, R. H. Álvarez-Gutiérrez, M. Armante, T. Baug, M. Bonfand, S. Bontemps, J. Braine, N. Brouillet, G. Busquet, D. J. Díaz-González, J. Di Francesco, A. Gusdorf, F. Herpin, H. Liu, A. López-Sepulcre, F. Louvet, X. Lu, L. Maud, T. Nony, F. A. Olguin, Y. Pouteau, R. Rivera-Soto, N. A. Sandoval-Garrido, P. Sanhueza, K. Tatematsu, A. P. M. Towner, M. Valeille-Manet
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.14710
Pdf link: https://arxiv.org/pdf/2306.14710
Abstract
ALMA-IMF is an Atacama Large Millimeter/submillimeter Array (ALMA) Large Program designed to measure the core mass function (CMF) of 15 protoclusters chosen to span their early evolutionary stages. It further aims to understand their kinematics, chemistry, and the impact of gas inflow, accretion, and dynamics on the CMF. We present here the first release of the ALMA-IMF line data cubes (DR1), produced from the combination of two ALMA 12m-array configurations. The data include 12 spectral windows, with eight at 1.3mm and four at 3mm. The broad spectral coverage of ALMA-IMF (~6.7 GHz bandwidth coverage per field) hosts a wealth of simple atomic, molecular, ionised, and complex organic molecular lines. We describe the line cube calibration done by ALMA and the subsequent calibration and imaging we performed. We discuss our choice of calibration parameters and optimisation of the cleaning parameters, and we demonstrate the utility and necessity of additional processing compared to the ALMA archive pipeline. As a demonstration of the scientific potential of these data, we present a first analysis of the DCN (3-2) line. We find that DCN traces a diversity of morphologies and complex velocity structures, which tend to be more filamentary and widespread in evolved regions and are more compact in the young and intermediate-stage protoclusters. Furthermore, we used the DCN (3-2) emission as a tracer of the gas associated with 595 continuum cores across the 15 protoclusters, providing the first estimates of the core systemic velocities and linewidths within the sample. We find that DCN (3-2) is detected towards a higher percentage of cores in evolved regions than the young and intermediate-stage protoclusters and is likely a more complete tracer of the core population in more evolved protoclusters. The full ALMA 12m-array cubes for the ALMA-IMF Large Program are provided with this DR1 release.

by olozhika (Xing Yuchen).

2023-06-27

New submissions for Tue, 6 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 7papers

Characterizing the Directionality of Gravitational Wave Emission from Matter Motions within Core-collapse Supernovae

Authors: Michael A. Pajkos, Steven J. VanCamp, Kuo-Chuan Pan, David Vartanyan, Nils Deppe, Sean M. Couch
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.01919
Pdf link: https://arxiv.org/pdf/2306.01919
Abstract
We analyze the directional dependence of the gravitational wave (GW) emission from 15 3D neutrino radiation hydrodynamic simulations of core-collapse supernovae. We develop a new analytic technique to characterize the distribution of GW emission over all angles. We use physics-informed toy models to provide closed form expressions for the distribution of GW emission for different CCSN phases. Using these toy models, we approximate the PNS dynamics during multiple CCSN stages and obtain similar GW distributions to simulation outputs. By applying this new technique throughout the supernova duration, we construct a distribution of preferred directions of GW emission. Our findings indicate CCSNe do not have a single `optimal' viewing angle along which the strongest GWs can be detected. For nonrotating cases, this dominant viewing angle drifts isotropically throughout the supernova, set by the dynamical timescale of the protoneutron star. For rotating cases, during core bounce and the following tens of ms, the strongest GW signal is observed along the equator. During the accretion phase, comparable -- if not stronger -- GW amplitudes are generated along the axis of rotation, which can be enhanced by the low T/|W| instability. We show two dominant factors influencing the directionality of GW emission are the degree of initial rotation and explosion morphology. Lastly, looking forward, we note the sensitive interplay between GW detector site and supernova orientation, along with its effect on detecting individual polarization modes.

In Search of Global 21-cm Signal using Artificial Neural Network in light of EDGES and ARCADE 2

Authors: Vivekanand Mohapatra, Johnny J, Pravin Kumar Natwariya, Jishnu Goswami, Alekha C. Nayak
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2306.02039
Pdf link: https://arxiv.org/pdf/2306.02039
Abstract
Understanding the astrophysical nature of the first stars still remains an unsolved problem in cosmology. The redshifted global 21-cm signal and power spectrum act as a treasure trove to probe the Cosmic Dawn era -- when the intergalactic medium was mostly neutral. Many experiments, like SARAS 3, SKA, EDGES, DARE, etc., have been proposed to probe the cosmic dawn era. However, extracting the faint cosmological signal buried inside the brighter foregrounds $\mathcal{O}(10^4)$ remains challenging. Considering the excess radio background, we have constructed all possible $T_{21}$ signals in the EDGES limit. We have used a single Artificial Neural Network for $T_{21}$ parameter extraction in the presence of the foreground and noise with Root Mean Square Error (RMSE) and R-Squared (R2) score of $(0.2 - 0.08)$ and $(0.66 - 0.94)$, respectively. Here, we also explore the parameter estimation in the presence of heating of intergalactic medium due to background radio radiation mediated by Ly$\alpha$ photons from first stars, and we found that the effect indeed has a significant impact on parameters correlation and their estimation.

The Orbital Structure and Selection Effects of the Galactic Center S-Star Cluster

Authors: Andreas Burkert, Stefan Gillessen, Douglas N.C. Lin, Xiaochen Zheng, Philipp Schoeller, Frank Eisenhauer, Reinhard Genzel
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.02076
Pdf link: https://arxiv.org/pdf/2306.02076
Abstract
The orbital distribution of the S-star cluster surrounding the supermassive black hole in the center of the Milky Way is analyzed. A tight, roughly exponential dependence of the pericenter distance r${p}$ on orbital eccentricity e${\star}$ is found, $\log ($r$p)\sim$(1-e${\star}$), which cannot be explained simply by a random distribution of semi-major axes and eccentricities. No stars are found in the region with high e${\star}$ and large log r${p}$ or in the region with low e${\star}$ and small log r${p}$. G-clouds follow the same correlation. The likelihood P(log r$p$,(1-e${\star}$)) to determine the orbital parameters of S-stars is determined. P is very small for stars with large e${\star}$ and large log r${p}$. S-stars might exist in this region. To determine their orbital parameters, one however needs observations over a longer time period. On the other hand, if stars would exist in the region of low log r${p}$ and small e${\star}$, their orbital parameters should by now have been determined. That this region is unpopulated therefore indicates that no S-stars exist with these orbital characteristics, providing constraints for their formation. We call this region, defined by $\log$ (r$p$/AU) $<$ 1.57+2.6(1-e${\star})$, the zone of avoidance. Finally, it is shown that the observed frequency of eccentricities and pericenter distances is consistent with a random sampling of log r${p}$ and e${\star}$. However, only if one takes into account that no stars exist in the zone of avoidance and that orbital parameters cannot yet be determined for stars with large r${p}$ and large e${\star}$.

Meterwavelength Single-pulse Polarimetric Emission Survey. VI. Towards understanding the Phenomenon of Pulsar Polarization in Partially Screened Vacuum Gap model

Authors: Dipanjan Mitra, George I. Melikidze, Rahul Basu
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.02537
Pdf link: https://arxiv.org/pdf/2306.02537
Abstract
We have observed 123 pulsars with periods longer than 0.1 seconds in the Meterwavelength Single-pulse Polarimetric Emission Survey. In this work a detailed study of polarization behaviour of these pulsars have been carried out. We were able to fit the rotating vector model to the polarization position angle sweeps in 68 pulsars, and in 34 pulsars the emission heights could be measured. In all cases the radio emission was constrained to arise below 10% of the light cylinder radius. In pulsars with low spindown energy loss, $\dot{E}<10^{34}$ ergs s$^{-1}$, we found the mean fractional linear polarization of the individual times samples in single pulses to be around 0.57 (57%) which is significantly larger than the fractional linear polarization of 0.29 (29%) obtained from the average profiles. On the other hand the mean fractional circular polarization of the individual time samples in single pulses is around 0.08 (8%), similar to the measurements from the average profiles. To explain the observed polarization features, we invoke the partially screened vacuum gap model of pulsars, where dense spark associated plasma clouds exist with high pair plasma multiplicity, with significant decrease of density in the regions between the clouds, that are dominated by iron ions. The coherent radio emission is excited by curvature radiation from charge bunches in these dense plasma clouds and escape as linearly polarized waves near cloud boundaries. We suggest that the circular polarization arises due to propagation of waves in the low pair multiplicity, ion dominated inter-cloud regions.

binary_c-python: A Python-based stellar population synthesis tool and interface to binary_c

Authors: D.D. Hendriks, R.G. Izzard
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.02779
Pdf link: https://arxiv.org/pdf/2306.02779
Abstract
We present the software package binary_c-python which provides a convenient and easy-to-use interface to the binary_c framework, allowing the user to rapidly evolve individual systems and populations of stars. binary_c-python is available on Pip and on GitLab. binary_c-python contains many useful features to control and process the output of binary_c, like by providing binary_c-python with logging statements that are dynamically compiled and loaded into binary_c. Moreover, we have recently added standardised output of events like Roche-lobe overflow or double compact-object formation to binary_c, and automatic parsing and managing of that output in binary_c-python. binary_c-python uses multiprocessing to utilise all the cores on a particular machine, and can run populations with HPC cluster workload managers like HTCondor and Slurm, allowing the user to run simulations on large computing clusters. We provide documentation that is automatically generated based on docstrings and a suite of Jupyter notebooks. These notebooks consist of technical tutorials on how to use binary_c-python and use-case scenarios aimed at doing science. Much of binary_c-python is covered by unit tests to ensure reliability and correctness, and the test coverage is continually increased as the package is improved.

FAUST X. Multi-band, multi-scale dust study of L1527 IRS. Evidence for dust properties variations within the envelope of a Class 0/I YSO

Authors: L. Cacciapuoti, E. Macias, A. J. Maury, C. J. Chandler, N. Sakai, Ł. Tychoniec, S. Viti, A. Natta, M. De Simone, A. Miotello, C. Codella, C. Ceccarelli, L. Podio, D. Fedele, D. Johnstone, Y. Shirley, B. J. Liu, E. Bianchi, Z. E. Zhang, J. Pineda, L. Loinard, F. Ménard, U. Lebreuilly, R. S. Klessen, P. Hennebelle, S. Molinari, L. Testi, S. Yamamoto
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.02852
Pdf link: https://arxiv.org/pdf/2306.02852
Abstract
Early dust grain growth in protostellar envelopes infalling on young discs has been suggested in recent studies, supporting the hypothesis that dust particles start to agglomerate already during the Class 0/I phase of young stellar objects (YSOs). If this early evolution were confirmed, it would impact the usually assumed initial conditions of planet formation, where only particles with sizes $\lesssim 0.25 \mu$m are usually considered for protostellar envelopes. We aim to determine the maximum grain size of the dust population in the envelope of the Class 0/I protostar L1527 IRS, located in the Taurus star-forming region (140 pc). We use Atacama Large millimetre/sub-millimetre Array (ALMA) and Atacama Compact Array (ACA) archival data and present new observations, in an effort to both enhance the signal-to-noise ratio of the faint extended continuum emission and properly account for the compact emission from the inner disc. Using observations performed in four wavelength bands and extending the spatial range of previous studies, we aim to place tight constraints on the spectral ($\alpha$) and dust emissivity ($\beta$) indices in the envelope of L1527 IRS. We find a rather flat $\alpha \sim$ 3.0 profile in the range 50-2000 au. Accounting for the envelope temperature profile, we derive values for the dust emissivity index, 0.9 < $\beta$ < 1.6, and reveal a tentative, positive outward gradient. This could be interpreted as a distribution of mainly ISM-like grains at 2000 au, gradually progressing to (sub-)millimetre-sized dust grains in the inner envelope, where at R=300 au, $\beta$ = 1.1 +/- 0.1. Our study supports a variation of the dust properties in the envelope of L1527 IRS. We discuss how this can be the result of in-situ grain growth, dust differential collapse from the parent core, or upward transport of disc large grains.

Searching for signatures of H $α$ spicule-like features in the solar transition region

Authors: Nived Vilangot Nhalil, Juie Shetye, J. Gerry Doyle
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.02945
Pdf link: https://arxiv.org/pdf/2306.02945
Abstract
New instrumental and telescopes covering the optical and ultra-violet spectral regions have revealed a range of small-scale dynamic features, many which may be related. For example, the range of spicule-like features hints towards a spectrum of features and not just two types; however, direct observational evidence in terms of tracking spicules across multiple wavelengths are needed in order to provide further insight into the dynamics of the Sun's outer atmosphere. This paper uses H $\alpha$ data obtained with the CRisp Imaging SpectroPolarimeter instrument on the Swedish 1-m Solar Telescope, and in the transition region using the Interface Region Imaging Spectrograph with the SJI 1400 {\AA} channel plus spectral data via the Si IV 1394 {\AA} line to track spicules termed Rapid Blue-shifted Excursions (RBEs). The RBEs as seen in the H $\alpha$ blue-wing images presented here can be sub-divided into two categories; a single or multi-threaded feature. Based on the H $\alpha$ spectra, the features can be divided into events showing broadening and line core absorption, events showing broadening and line core emission, events with a pure blue shifted H $\alpha$ profile without any absorption in the red wing, broadened line profile with the absorption in the blue stronger compared to the red wing. From the RBE-like events which have a Si IV 1394 {\AA} line profile, 78% of them show a Si IV line flux increase. Most of these features show a second broadened Si IV component which is slightly blue-shifted.

by olozhika (Xing Yuchen).

2023-06-06

New submissions for Mon, 22 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster']

Today: 15papers

Implementation of Rare Isotopologues into Machine Learning of the Chemical Inventory of the Solar-Type Protostellar Source IRAS 16293-2422

Authors: Zachary T.P. Fried, Kin Long Kelvin Lee, Alex N. Byrne, Brett A. McGuire
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11193
Pdf link: https://arxiv.org/pdf/2305.11193
Abstract
Machine learning techniques have been previously used to model and predict column densities in the TMC-1 dark molecular cloud. In interstellar sources further along the path of star formation, such as those where a protostar itself has been formed, the chemistry is known to be drastically different from that of largely quiescent dark clouds. To that end, we have tested the ability of various machine learning models to fit the column densities of the molecules detected in source B of the Class 0 protostellar binary IRAS 16293-2422. By including a simple encoding of isotopic composition in our molecular feature vectors, we also examine for the first time how well these models can replicate the isotopic ratios. Finally, we report the predicted column densities of the chemically relevant molecules that may be excellent targets for radioastronomical detection in IRAS 16293-2422B.

Fast Neutrino Flavor Conversions can Help and Hinder Neutrino-Driven Explosions

Authors: Jakob Ehring (1,2,3), Sajad Abbar (1), Hans-Thomas Janka (2), Georg Raffelt (1), Irene Tamborra (4) ((1) MPI Physik, (2) MPI Astrophysik, (3) TUM Garching, (4) Niels Bohr Institute)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2305.11207
Pdf link: https://arxiv.org/pdf/2305.11207
Abstract
We present the first simulations of core-collapse supernovae (CCSNe) in axial symmetry (2D) with feedback from fast neutrino flavor conversion (FFC). Our schematic treatment of FFCs assumes instantaneous flavor equilibration under the constraint of lepton-number conservation. Systematically varying the spatial domain where FFCs are assumed to occur, we find that they facilitate SN explosions in low-mass (9-12 solar masses) progenitors that otherwise explode with longer time delays, whereas FFCs weaken the tendency to explode of higher-mass (around 20 solar masses) progenitors.

Fitting Probability Distribution Functions in Turbulent Star-Forming Molecular Clouds

Authors: Avery Kiihne, Sabrina M. Appel, Blakesley Burkhart, Vadim A. Semenov, Christoph Federrath
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11218
Pdf link: https://arxiv.org/pdf/2305.11218
Abstract
We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution functions (PDFs). The first method fits a piecewise lognormal and power-law (PL) function to recover PDF parameters such as the PL slope and transition density. The second method fits a polynomial spline function and examines the first and second derivatives of the spline to determine the PL slope and the functional transition density. We demonstrate that fitting a spline allows us to directly determine if the data has multiple PL slopes. The first PL (set by the transition between lognormal and PL function) can also be visualized in the derivatives directly. In general, the two methods produce fits that agree reasonably well for volume density but vary for column density, likely due to the increased statistical noise in column density maps as compared to volume density. We test a well-known conversion for estimating volume density PL slopes from column density slopes and find that the spline method produces a better match (\c{hi}2 of 2.38 vs \c{hi}2 of 5.92), albeit with a significant scatter. Ultimately, we recommend the use of both fitting methods on column density data to mitigate the effects of noise.

Planetesimal formation via the streaming instability with multiple grain sizes

Authors: Josef Rucska, James Wadsley
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.11297
Pdf link: https://arxiv.org/pdf/2305.11297
Abstract
Kilometre-sized planetesimals form from pebbles of a range of sizes. We present the first simulations of the streaming instability that begin with a realistic, peaked size distribution, as expected from grain growth predictions. Our 3D numerical simulations directly form planetesimals via the gravitational collapse of pebble clouds. Models with multiple grain sizes show spatially distinct dust populations. The smallest grains in the size distribution do not participate in the formation of filaments or the planetesimals that are formed by the remaining ~80% of the dust mass. This implies a size cutoff for pebbles incorporated into asteroids and comets. Observations cannot resolve this dust clumping. However, we show that clumping, combined with optical depth effects, can cause significant underestimates of the dust mass, with 20%-80% more dust being present even at moderate optical depths if the streaming instability is active.

The JCMT BISTRO Survey: Studying the Complex Magnetic Field of L43

Authors: Derek Ward-Thompson, Janik Karoly, Kate Pattle, David Berry, Anthony Whitworth, Jason Kirk, Pierre Bastien, Tao-Chung Ching, Simon Coude, Jihye Hwang, Woojin Kwon, Archana Soam, Jia-Wei Wang, Tetsuo Hasegawa, Shih-Ping Lai, Keping Qiu, Doris Arzoumanian, Tyler L. Bourke, Do-Young Byun, Huei-Ru Vivien Chen, Wen Ping Chen, Mike Chen, Zhiwei Chen, Jungyeon Cho, Minho Choi, Youngwoo Choi, Yunhee Choi, Antonio Chrysostomou, Eun Jung Chung, Sophia Dai, Victor Debattista, James Di Francesco, Pham Ngoc Diep, Yasuo Doi, Hao-Yuan Duan, Yan Duan, Chakali Eswaraiah, Lapo Fanciullo, Jason Fiege, Laura M. Fissel, Erica Franzmann, Per Friberg, Rachel Friesen, Gary Fuller, Ray Furuya, Tim Gledhill, Sarah Graves, Jane Greaves, Matt Griffin, Qilao Gu, Ilseung Han, Thiem Hoang, Martin Houde, Charles L. H. Hull, et al. (104 additional authors not shown)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11306
Pdf link: https://arxiv.org/pdf/2305.11306
Abstract
We present observations of polarized dust emission at 850 $\mu$m from the L43 molecular cloud which sits in the Ophiuchus cloud complex. The data were taken using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope as a part of the BISTRO large program. L43 is a dense ($N_{\rm H_2}\sim 10^{22}$-10$^{23}$ cm$^{-2}$) complex molecular cloud with a submillimetre-bright starless core and two protostellar sources. There appears to be an evolutionary gradient along the isolated filament that L43 is embedded within, with the most evolved source closest to the Sco OB2 association. One of the protostars drives a CO outflow that has created a cavity to the southeast. We see a magnetic field that appears to be aligned with the cavity walls of the outflow, suggesting interaction with the outflow. We also find a magnetic field strength of up to $\sim$160$\pm$30 $\mu$G in the main starless core and up to $\sim$90$\pm$40 $\mu$G in the more diffuse, extended region. These field strengths give magnetically super- and sub-critical values respectively and both are found to be roughly trans-Alfv'enic. We also present a new method of data reduction for these denser but fainter objects like starless cores.

The role of grain size in AGN torus dust models

Authors: Omaira González-Martín, Cristina Ramos Almeida, Jacopo Fritz, Almudena Alonso-Herrero, Sebastian F. Hönig, Patrick F. Roche, Donaji Esparza-Arredondo, Ismael García-Bernete, Santiago García-Burillo, Natalia Osorio-Clavijo, Ulises Reyes-Amador, Marko Stalevski, César Victoria-Ceballos
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11331
Pdf link: https://arxiv.org/pdf/2305.11331
Abstract
Fits the infrared spectra from the nuclear regions of AGN can place constraints on the dust properties, distribution, and geometry by comparison with models. However, none of the currently available models fully describe the observations of AGN currently available. Among the aspects least explored, here we focus on the role of dust grain size. We offer the community a new spectral energy distribution (SED) library, hereinafter [GoMar23] model, which is based on the two-phase torus model developed before with the inclusion of the grain size as a model parameter, parameterized by the maximum grain size Psize or equivalently the mass-weighted average grain size < P >. We created 691,200 SEDs using the SKIRT code, where the maximum grain size can vary within the range Psize = 0.01 - 10.0um ( < P >= 0.007 - 3.41um). We fit this new and several existing libraries to a sample of 68 nearby and luminous AGNs with Spitzer/IRS spectra dominated by AGN-heated dust. We find that the [GoMar23] model can adequately reproduce up to 85-88% of the spectra. The dust grain size parameter significantly improves the final fit in up to 90% of these spectra. Statistical tests indicate that the grain size is the third most important parameter in the fitting procedure (after the size and half opening angle of the torus). The requirement of a foreground extinction by our model is lower compared to purely clumpy models. We find that 41% of our sample requires that the maximum dust grain size is as large as Psize =10um (< P >= 3.41um). Nonetheless, we also remark that disk+wind and clumpy torus models are still required to reproduce the spectra of a non-negligible fraction of objects, suggesting the need for several dust geometries to explain the infrared continuum of AGN. This work provides tentative evidence for dust grain growth in the proximity of the AGN.

Filling in the Gaps: Can Gravitationally Unstable Discs Form the Seeds of Gas Giant Planets?

Authors: Hans Baehr
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.11336
Pdf link: https://arxiv.org/pdf/2305.11336
Abstract
Circumstellar discs likely have a short window when they are self-gravitating and prone to the effects of disc instability, but during this time the seeds of planet formation can be sown. It has long been argued that disc fragmentation can form large gas giant planets at wide orbital separations, but its place in the planet formation paradigm is hindered by a tendency to form especially large gas giants or brown dwarfs. We instead suggest that planet formation can occur early in massive discs, through the gravitational collapse of dust which can form the seeds of giant planets. This is different from the usual picture of self-gravitating discs, in which planet formation is considered through the gravitational collapse of the gas disc into a gas giant precursor. It is familiar in the sense that the core is formed first, and gas is accreted thereafter, as is the case in the core accretion scenario. However, by forming a $\sim 1 M_{\oplus}$ seed from the gravitational collapse of dust within a self-gravitating disc there exists the potential to overcome traditional growth barriers and form a planet within a few times $10^5$ years. The accretion of pebbles is most efficient with centimetre-sized dust, but the accretion of millimetre sizes can also result in formation within a Myr. Thus, if dust can grow to these sizes, planetary seeds formed within very young, massive discs could drastically reduce the timescale of planet formation and potentially explain the observed ring and gap structures in young discs.

The origin of low-redshift event rate excess as revealed by the low-luminosity GRBs

Authors: X. F. Dong, Z. B. Zhang, Q. M. Li, Y. F. Huang, K. Bian
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Arxiv link: https://arxiv.org/abs/2305.11380
Pdf link: https://arxiv.org/pdf/2305.11380
Abstract
The relation between the event rate of long Gamma-Ray Bursts at low redshift and the star formation rate is still controversial, especially in the low-redshift end. Dong et al. confirmed that the Gamma-Ray Burst rate always exceeds the star formation rate at low-redshift of z < 1 in despite of the sample completeness. However, the reason of low-redshift excess is still unclear. Considering low-luminosity bursts with smaller redshift generally, we choose three Swift long burst samples and classify them into low- and high-luminosity bursts in order to check whether the low-redshift excess is existent and if the excess is biased by the sample size and completeness. To degenerate the redshift evolution from luminosity, we adopt the non-parametric method to study the event rate of the two types of long bursts in each sample. It is found that the high-luminosity burst rates are consistent with the star formation rate within the whole redshift range while the event rates of low-luminosity bursts exceed the star formation rate at low redshift of z < 1. Consequently, we conclude that the low-redshift excess is contributed by the low-luminosity bursts with possibly new origins unconnected with the star formation, which is also independent of the sample size and the sample completeness.

Properties and Asteroseismological analysis of a new ZZ ceti discovered by TMTS

Authors: Jincheng Guo, Yanhui Chen, Xiaofeng Wang, Jie Lin, Gaobo Xi, Jun Mo, Alexei V. Filippenko, Thomas Brink, Xiao-Yu Ma, Weikai Zong, Yong Yang, Jingkun Zhao, Xiangyun Zeng, Zhihao Chen, Ali Esamdin, Fangzhou Guo, Abdusamatjan Iskandar, Xiaojun Jiang, Wenxiong Li, Cheng Liu, Jianrong Shi, Xuan Song, Letian Wang, Danfeng Xiang, Shengyu Yan, Jicheng Zhang, Yonghui Yang
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.11585
Pdf link: https://arxiv.org/pdf/2305.11585
Abstract
Tsinghua university-Ma Huateng Telescope for Survey (TMTS) aims to discover rapidly evolving transients by monitoring the northern sky. The TMTS catalog is cross-matched with the white dwarf (WD) catalog of Gaia EDR3, and light curves of more than a thousand WD candidates are obtained so far. Among them, the WD TMTS J23450729+5813146 (hereafter J2345) is one interesting common source. Based on the light curves from the TMTS and follow-up photometric observations, periods of 967.113 s, 973.734 s, 881.525 s, 843.458 s, 806.916 s and 678.273 s are identified. In addition, the TESS observations suggest a 3.39 h period but this can be attributed to the rotation of a comoving M dwarf located within 3". The spectroscopic observation indicates that this WD is DA type with Teff = 11778+/-617K,log g = 8.38+/-0.31,mass=0.84+/-0.20Msun and age=0.704+/-0.377 Gyrs. Asteroseismological analysis reveals a global best-fit solution of Teff =12110+/-10K and mass=0.760+/-0.005Msun,consistent with the spectral fitting results, and Oxygen and Carbon abundances in the core center are 0.73 and 0.27, respectively. The distance derived from the intrinsic luminosity given by asteroseismology is 93 parsec, which is in agreement with the distance of 98 parsec from Gaia DR3. Additionally, kinematic study shows that this WD is likely a thick disk star. The mass of its zero-age main-sequence mass is estimated to be 3.08 Msun and has a main-sequence plus cooling age of roughly 900 Myrs.

Sapaki: Galactic O3If* star possibly born in isolation

Authors: M. S. Zarricueta Plaza, A. Roman-Lopes, D. Sanmartim
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11612
Pdf link: https://arxiv.org/pdf/2305.11612
Abstract
Context: The study of high-mass stars found to be isolated in the field of the Milky Way may help to probe the feasibility of the core-accretion mechanism in the case of massive star formation. The existence of truly isolated stars may efficiently probe the possibility that individual massive stars can be born in isolation. Aims: We observed WR67a (hereafter Sapaki), an O3If* star that appears to be isolated close to the center of a well-developed giant cavity that is aptly traced by 8.0 $\mu$m hot dust emission. Methods: We acquired medium-resolution ($R=4100$) and moderate signal-to-noise ($S/N = 95$ at 4500 \r{A}) spectra for Sapaki in the range of 3800-10500 \r{A} with the Magellan Echellette (MagE) at Las Campanas Observatory. We computed the line-of-sight total extinctions. Additionally, we restricted its heliocentric distance by using a range of different estimators. Moreover, we measured its radial velocity from several lines in its spectrum. Finally, we analyzed its proper motions from Gaia to examine its possible runaway status. Results: The star has been classified as having the spectral type O3If* given its resemblance to standard examples of the class. In addition, we found that Sapaki is highly obscured, reaching a line-of-sight extinction value of $A_{V} = 7.87$. We estimated the heliocentric distance to be in the range of $d = 4-7$ kpc. We also estimated its radial velocity to be $V_{r} = -34.2 \pm 15.6$ km/s. We may also discard its runaway status solely based on its 2D kinematics. Furthermore, by analyzing proper motions and parallaxes provided by Gaia, we found only one other star with compatible measurements. Conclusions: Given its apparent non-runaway status and the absence of clustering, Sapaki appears to be a solid candidate for isolated high-mass star formation in the Milky Way.

CN and CO Features: Key Indicators of Red Giant Evolutionary Phase in Moderate-Resolution X-Shooter Spectra

Authors: Kirsten A. Banks, Chantel Y. Y. Ho, Sarah L. Martell, Sven Buder, Dennis Stello, Sanjib Sharma, James Priest, Anaïs Gonneau, Keith Hawkins
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11620
Pdf link: https://arxiv.org/pdf/2305.11620
Abstract
Data-driven analysis methods can help to infer physical properties of red giant stars where "gold-standard" asteroseismic data are not available. The study of optical and infrared spectra of red giant stars with data-driven analyses has revealed that differences in oscillation frequencies and their separations are imprinted in said spectra. This makes it possible to confidently differentiate core-helium burning red clump stars (RC) from those that are still on their first ascent of the red giant branch (RGB). We extend these studies to a tenfold larger wavelength range of 0.33 to 2.5 microns with the moderate-resolution VLT/X-shooter spectrograph. Our analysis of 49 stars with asteroseismic data from the K2 mission confirms that CN, CO and CH features are indeed the primary carriers of spectroscopic information on the evolutionary stages of red giant stars. We report 215 informative features for differentiating the RC from the RGB within the range of 0.33 to 2.5 microns. This makes it possible for existing and future spectroscopic surveys to optimize their wavelength regions to deliver both a large variety of elemental abundances and reliable age estimates of luminous red giant stars.

Rotation-tunneling spectrum and astrochemical modeling of dimethylamine, CH$_3$NHCH$_3$, and searches for it in space

Authors: H. S. P. Müller, R. T. Garrod, A. Belloche, V. M. Rivilla, K. M. Menten, I. Jiménez-Serra, J. Martín-Pintado, F. Lewen, S. Schlemmer
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); Atomic and Molecular Clusters (physics.atm-clus)
Arxiv link: https://arxiv.org/abs/2305.11656
Pdf link: https://arxiv.org/pdf/2305.11656
Abstract
Methylamine has been the only simple alkylamine detected in the interstellar medium for a long time. With the recent secure and tentative detections of vinylamine and ethylamine, respectively, dimethylamine has become a promising target for searches in space. Its rotational spectrum, however, has been known only up to 45 GHz until now. Here we investigate the rotation-tunneling spectrum of dimethylamine in selected regions between 76 and 1091 GHz using three different spectrometers in order to facilitate its detection in space. The quantum number range is extended to $J = 61$ and $K_a = 21$, yielding an extensive set of accurate spectroscopic parameters. To search for dimethylamine, we refer to the spectral line survey ReMoCA carried out with the Atacama Large Millimeter/submillimeter Array toward the high-mass star-forming region Sagittarius B2(N) and a spectral line survey of the molecular cloud G+0.693$-$0.027 employing the IRAM 30 m and Yebes 40 m radio telescopes. We report nondetections of dimethylamine toward the hot molecular cores Sgr B2(N1S) and Sgr B2(N2b) as well as G+0.693$-$0.027 which imply that dimethylamine is at least 14, 4.5 and 39 times less abundant than methylamine toward these sources, respectively. The observational results are compared to computational results from a gas-grain astrochemical model. The modeled methylamine to dimethylamine ratios are compatible with the observational ratios. However, the model produces too much ethylamine compared with methylamine which could mean that the already fairly low levels of dimethylamine in the models may also be too high.

EUV fine structure and variability associated with coronal rain revealed by Solar Orbiter/EUI HRIEUV and SPICE

Authors: P. Antolin, A. Dolliou, F. Auchère, L. P. Chitta, S. Parenti, D. Berghmans, R. Aznar Cuadrado, K. Barczynski, S. Gissot, L. Harra, Z. Huang, M. Janvier, E. Kraaikamp, D. M. Long, S. Mandal, H. Peter, L. Rodriguez, U. Schühle, P. J. Smith, S. K. Solanki, K. Stegen, L. Teriaca, C. Verbeeck, M. J. West, A. N. Zhukov, T. Appourchaux, G. Aulanier, E. Buchlin, F. Delmotte, J. M. Gilles, M. Haberreiter, J.-P. Halain, K. Heerlein, J.-F. Hochedez, M. Gyo, S. Poedts, P. Rochus
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11691
Pdf link: https://arxiv.org/pdf/2305.11691
Abstract
Coronal rain is the most dramatic cooling phenomenon of the solar corona and an essential diagnostic tool for the coronal heating properties. A puzzling feature of the solar corona, besides the heating, is its EUV filamentary structure and variability. We aim to identify observable features of the TNE-TI scenario underlying coronal rain at small and large spatial scales, to understand the role it plays in the solar corona. We use EUV datasets at unprecedented spatial resolution of ~240 km from EUI/HRIEUV and SPICE of Solar Orbiter from the spring 2022 perihelion. EUV absorption features produced by coronal rain are detected at scales as small as 260 km. As the rain falls, heating and compression is produced immediately downstream, leading to a small EUV brightening accompanying the fall and producing a "fireball" phenomenon. Just prior to impact, a flash-like EUV brightening downstream of the rain, lasting a few minutes is observed for the fastest events. For the first time, we detect the atmospheric response to the rain's impact on the chromosphere and consists of upward propagating rebound shocks and flows partly reheating the loop. The observed widths of the rain clumps are 500 +- 200 km. They exhibit a broad velocity distribution of 10 - 150 km s^-1, peaking below 50 km s^-1. Coronal strands of similar widths are observed along the same loops co-spatial with cool filamentary structure, which we interpret as the CCTR. Matching with the expected cooling, prior to the rain appearance sequential loop brightenings are detected in gradually cooler lines from corona to chromospheric temperatures. Despite the large rain showers, most cannot be detected in AIA 171 in quadrature, indicating that LOS effects play a major role in coronal rain visibility. Still, AIA 304 and SPICE observations reveal that only a small fraction of the rain can be captured by HRIEUV.

Alpha-Meteoroids then and now: Unearthing an overlooked micrometeoroid population

Authors: Maximilian Sommer
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.11698
Pdf link: https://arxiv.org/pdf/2305.11698
Abstract
The term $\alpha$-meteoroid' was introduced to describe a group of micrometeoroids with certain dynamical properties, which -- alongside the group of the $\beta$-meteoroids -- had been identified by the first generation of reliable in-situ dust detectors in interplanetary space. In recent years, use of the term $\alpha$-meteoroid has become more frequent again, under a subtly but crucially altered definition. This work shall bring attention to the discrepancy between the term's original and newly established meaning, and spotlight the now-overlooked group of particles that the term used to describe. We review past and present pertinent literature around the term $\alpha$-meteoroid, and assess the dynamics of the originally referred-to particles with respect to possible sources, showing that their formation is the expected consequence of collisional grinding of the zodiacal cloud at short heliocentric distances. The abundance of the original $\alpha$-meteoroids, which are essentially bound $\beta$-meteoroids', makes them relevant to all in-situ dust experiments in the inner solar system. Due to the change of the term's meaning, however, they are not considered by contemporary studies. The characterization of this particle population could elucidate the processing of the innermost zodiacal cloud, and should thus be objective of upcoming in-situ dust experiments. The attained ambiguity of the term $\alpha$-meteoroid is not easily resolved, warranting great care and clarity going forward.

Constraints on star formation in Orion A from Gaia

Authors: Jairo A. Alzate, Gustavo Bruzual, Marina Kounkel, Gladis Magris, Lee Hartmann, Nuria Calvet, Lyra Cao
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.11823
Pdf link: https://arxiv.org/pdf/2305.11823
Abstract
We develop statistical methods within a Bayesian framework to infer the star formation history from photometric surveys of pre-main sequence populations. Our procedures include correcting for biases due to extinction in magnitude-limited surveys, and using distributions from subsets of stars with individual extinction measurements. We also make modest corrections for unresolved binaries. We apply our methods to samples of populations with Gaia photometry in the Orion A molecular cloud. Using two well-established sets of evolutionary tracks, we find that, although our sample is incomplete at youngest ages due to extinction, star formation has proceeded in Orion A at a relatively constant rate between ages of about 0.3 and 5 Myr, in contrast to other studies suggesting multiple epochs of star formation. Similar results are obtained for a set of tracks that attempt to take the effects of strong magnetic fields into account. We also find no evidence for a well-constrained "birthline" that would result from low-mass stars appearing first along the deuterium-burning main sequence, especially using the magnetic evolutionary tracks. While our methods have been developed to deal with Gaia data, they may be useful for analyzing other photometric surveys of star-forming regions.

by olozhika (Xing Yuchen).

2023-05-22

New submissions for Mon, 3 Jul 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

阅读 Usage.md了解如何使用此repo实现个性化的Arxiv论文推送

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Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 6papers

Calibrating angular momentum transport in intermediate-mass stars from gravity-mode asteroseismology

Authors: Joey S. G. Mombarg
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.17211
Pdf link: https://arxiv.org/pdf/2306.17211
Abstract
The physical mechanisms driving the transport of angular momentum in stars are not fully understood, as current models cannot explain the observed stellar rotation profiles across all stages of evolution. By making use of pulsating F-type dwarfs, this work aims at (i) observationally calibrating the efficiency of angular momentum transport, assuming a constant uniform viscosity, and (ii) testing how well state-of-the-art rotating stellar models with angular momentum (AM) transport by rotationally-induced processes can explain observed rotation profiles. In both cases, the aim is to simultaneously reproduce the measured near-core rotation and core-to-surface rotation ratio. Asteroseismic modelling is applied to a sample of seven slowly rotating pulsators, to derive (core) masses and ages from their gravity-mode oscillations. This work focuses on the main sequence, using models that start with an initial uniform rotation frequency at the start of core-hydrogen burning that is a free parameter. Two treatments of AM transport are considered: (i) a constant uniform viscosity, and (ii) rotationally-induced processes. Next, the initial rotation frequency of each star is derived from the observed present-day near-core rotation frequency for both treatments. To explain the near-core rotation rate at the inferred age, initial rotation frequencies at the zero-age main sequence need to be below 10 percent of the initial critical break-up frequency. A diffusive approximation of angular momentum transport can in general explain the observed rotation profiles of the six slowly-rotating F-type dwarfs, for average values of the viscosity between 2x10^5 and 5x10^7 cm^2/s or when the viscosity is computed from rotationally-induced mechanisms. Yet, for three stars in the sample, the core-to-surface rotation fraction from rotationally-induced mechanisms is predicted to be higher than observed.

Using the motion of S2 to constrain scalar clouds around SgrA*

Authors: GRAVITY Collaboration: A. Foschi, R. Abuter, N. Aimar, P. Amaro Seoane, A. Amorim, M. Bauböck, J.P. Berger, H. Bonnet, G. Bourdarot, W. Brandner, V. Cardoso, Y. Clénet, Y. Dallilar, R. Davies, P.T. de Zeeuw, D. Defrère, J. Dexter, A. Drescher, A. Eckart, F. Eisenhauer, M.C. Ferreira, N.M. Förster Schreiber, P.J.V. Garcia, F. Gao, E. Gendron, R. Genzel, S. Gillessen, T. Gomes, M. Habibi, X. Haubois, G. Heißel, T. Henning, S. Hippler, S.F. Hönig, M. Horrobin, L. Jochum, L. Jocou, A. Kaufer, P. Kervella, L. Kreidberg, S. Lacour, V. Lapeyrère, J.B. Le Bouquin, P. Léna, D. Lutz, F. Millour, T. Ott, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, S. Rabien, D.C. Ribeiro, M. Sadun Bordoni, S. Scheithauer, J. Shangguan, T. Shimizu, J. Stadler, O. Straub, C. Straubmeier, et al. (10 additional authors not shown)
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc)
Arxiv link: https://arxiv.org/abs/2306.17215
Pdf link: https://arxiv.org/pdf/2306.17215
Abstract
The motion of S2, one of the stars closest to the Galactic Centre, has been measured accurately and used to study the compact object at the centre of the Milky Way. It is commonly accepted that this object is a supermassive black hole but the nature of its environment is open to discussion. Here, we investigate the possibility that dark matter in the form of an ultralight scalar field ``cloud'' clusters around Sgr~A*. We use the available data for S2 to perform a Markov Chain Monte Carlo analysis and find the best-fit estimates for a scalar cloud structure. Our results show no substantial evidence for such structures. When the cloud size is of the order of the size of the orbit of S2, we are able to constrain its mass to be smaller than $0.1%$ of the central mass, setting a strong bound on the presence of new fields in the galactic centre.

Critical accretion rates for rapidly growing massive Population III stars

Authors: Devesh Nandal, John A. Regan, Tyrone E. Woods, Eoin Farrell, Sylvia Ekström, Georges Meynet
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.17223
Pdf link: https://arxiv.org/pdf/2306.17223
Abstract
Efforts to understand the origin and growth of massive black holes observed in the early Universe have spurred a strong interest in the evolution and fate of rapidly-accreting primordial (metal-free) stars. Here, we investigate the evolution of such Population III stars under variable accretion rates, focusing on the thermal response and stellar structure, the impact of the luminosity wave encountered early in the pre-main sequence phase, and the influence of accretion on their subsequent evolution. We employ the Geneva stellar evolution code and simulate ten models with varying accretion histories, covering a final mass range from 491 M${\odot}$ to 6127 M${\odot}$. Our findings indicate that the critical accretion rate delineating the red and blue supergiant regimes during the pre-main sequence evolution is approximately $2.5\times10^{-2} $M${\odot}$/yr. Once core hydrogen burning commences, the value of this critical accretion rate drops to $7.0\times10^{-3}$M${\odot}$/yr. Moreover, we also confirm that the Kelvin-Helmholtz timescale in the outer surface layers is the more relevant timescale for determining the transition between red and blue phases. Regarding the luminosity wave, we find that it affects only the early pre-main sequence phase of evolution and does not directly influence the transition between red and blue phases, which primarily depends on the accretion rate. Finally, we demonstrate that variable accretion rates significantly impact the lifetimes, surface enrichment, final mass and time spent in the red phase. Our study provides a comprehensive understanding of the intricate evolutionary patterns of Population III stars subjected to variable accretion rates.

Galactic Diffuse Neutrino Emission from Sources beyond the Discovery Horizon

Authors: Antonio Ambrosone, Kathrine Mørch Groth, Enrico Peretti, Markus Ahlers
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.17285
Pdf link: https://arxiv.org/pdf/2306.17285
Abstract
The IceCube Neutrino Observatory has recently reported strong evidence for neutrino emission from the Galactic plane. The signal is consistent with model predictions of diffuse emission from cosmic ray propagation in the interstellar medium. However, due to IceCube's limited potential of identifying individual neutrino sources, it is also feasible that unresolved Galactic sources could contribute to the observation. We investigate the contribution of this quasi-diffuse emission and show that the observed Galactic diffuse flux at 100~TeV could be dominated by hard emission of unresolved sources. Particularly interesting candidate sources are young massive stellar clusters that have been considered as cosmic-ray PeVatrons. We examine whether this hypothesis can be tested by the upcoming KM3NeT detector or the planned future facility IceCube-Gen2 with about five times the sensitivity of IceCube.

Reconstructing the mid-infrared environment in the stellar merger remnant V838 Monocerotis

Authors: Muhammad Zain Mobeen, Tomasz Kamiński, Alexis Matter, Markus Wittkowski, John D. Monnier, Stefan Kraus, Jean-Baptiste Le Bouquin, Narsireddy Anugu, Theo Ten Brummelaar, Claire L. Davies, Jacob Ennis, Tyler Gardner, Aaron Labdon, Cyprien Lanthermann, Gail H. Schaefer, Benjamin R. Setterholm, Nour Ibrahim, Steve B. Howell
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.17586
Pdf link: https://arxiv.org/pdf/2306.17586
Abstract
V838 Mon is a stellar merger remnant that erupted in 2002 in a luminous red novae event. Although it is well studied in the optical, near infrared and submillimeter regimes, its structure in the mid-infrared wavelengths remains elusive. We observed V838 Mon with the MATISSE (LMN bands) and GRAVITY (K band) instruments at the VLTI and also the MIRCX/MYSTIC (HK bands) instruments at the CHARA array. We geometrically modelled the squared visibilities and the closure phases in each of the bands to obtain constraints on physical parameters. Furthermore, we constructed high resolution images of V838 Mon in the HK bands, using the MIRA and SQUEEZE algorithms to study the immediate surroundings of the star. Lastly, we also modelled the spectral features seen in the K and M bands at various temperatures. The image reconstructions show a bipolar structure that surrounds the central star in the post merger remnant. In the K band, the super resolved images show an extended structure (uniform disk diameter $\sim 1.94$ mas) with a clumpy morphology that is aligned along a north-west position angle (PA) of $-40^\circ$. Whereas in the H band, the extended structure (uniform disk diameter $\sim 1.18$ mas) lies roughly along the same PA. However, the northern lobe is slightly misaligned with respect to the southern lobe, which results in the closure phase deviations. The VLTI and CHARA imaging results show that V838 Mon is surrounded by features that resemble jets that are intrinsically asymmetric. This is also confirmed by the closure phase modelling. Further observations with VLTI can help to determine whether this structure shows any variation over time, and also if such bipolar structures are commonly formed in other stellar merger remnants.

Deep Search for Glycine Conformers in Barnard 5

Authors: Tadeus Carl, Eva Wirström, Per Bergman, Steven Charnley, Yo-Ling Chuang, Yi-Jehng Kuan
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.17713
Pdf link: https://arxiv.org/pdf/2306.17713
Abstract
One of the most fundamental hypotheses in astrochemistry and astrobiology states that crucial biotic molecules like glycine (NH$_2$CH$2$COOH) found in meteorites and comets are inherited from early phases of star formation. Most observational searches for glycine in the interstellar medium have focused on warm, high-mass molecular cloud sources. However, recent studies suggest that it might be appropriate to shift the observational focus to cold, low-mass sources. We aim to detect glycine towards the so-called methanol hotspot in the Barnard 5 dark cloud. The hotspot is a cold source ($T\mathrm{gas}\approx 7.5$ K) with yet high abundances of complex organic molecules (COMs) and water in the gas phase. We carried out deep, pointed observations with the Onsala 20m telescope, targeting several transitions of glycine conformers I and II (Gly-I and Gly-II) in the frequency range $70.2$-$77.9$ GHz. No glycine lines are detected towards the targeted position, but we use a line stacking procedure to derive sensitive abundance upper limits w.r.t. H$_2$ for Gly-I and Gly-II, i.e. $\leq(2$-$5)\times10^{-10}$ and $\leq(0.7$-$3)\times10^{-11}$, respectively. The obtained Gly-II upper limits are the most stringent for a cold source, while the Gly-I upper limits are mostly on the same order as previously measured limits. The measured abundances w.r.t. H$_2$ of other COMs at the B5 methanol hotspot range from $2\times10^{-10}$ (acetaldehyde) to $2\times10^{-8}$ (methanol). Hence, based on a total glycine upper limit of $(2$-$5)\times10^{-10}$, we cannot rule out that glycine is present but undetected.

by olozhika (Xing Yuchen).

2023-07-03

New submissions for Fri, 30 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

阅读 Usage.md了解如何使用此repo实现个性化的Arxiv论文推送
See Usage.md for instructions on how to personalize the repo.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 8papers

As Simple as Possible but No Simpler: Optimizing the Performance of Neural Net Emulators for Galaxy SED Fitting

Authors: Elijah P. Mathews, Joel Leja, Joshua S. Speagle, Benjamin D. Johnson, Justus Gibson, Erica J. Nelson, Katherine A. Suess, Sandro Tacchella, Katherine E. Whitaker, Bingjie Wang
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Arxiv link: https://arxiv.org/abs/2306.16442
Pdf link: https://arxiv.org/pdf/2306.16442
Abstract
Artificial neural network emulators have been demonstrated to be a very computationally efficient method to rapidly generate galaxy spectral energy distributions (SEDs), for parameter inference or otherwise. Using a highly flexible and fast mathematical structure, they can learn the nontrivial relationship between input galaxy parameters and output observables. However, they do so imperfectly, and small errors in flux prediction can yield large differences in recovered parameters. In this work, we investigate the relationship between an emulator's execution time, uncertainties, correlated errors, and ability to recover accurate posteriors. We show that emulators can recover consistent results to traditional fits, with precision of $25!-!40%$ in posterior medians for stellar mass, stellar metallicity, star formation rate, and stellar age. We find that emulation uncertainties scale with an emulator's width $N$ as $\propto N^{-1}$ while execution time scales as $\propto N^2$, resulting in an inherent tradeoff between execution time and emulation uncertainties. We also find that emulators with uncertainties smaller than observational uncertaities are able to recover accurate posteriors for most parameters without a significant increase in catastrophic outliers. Furthermore, we demonstrate that small architectures can produce flux residuals that have significant correlations, which can create dangerous systematic errors in colors. Finally, we show that the distributions chosen for generating training sets can have a large effect on emulators' ability to accurately fit rare objects. Selecting the optimal architecture and training set for an emulator will minimize the computational requirements for fitting near-future large-scale galaxy surveys.

Light and colour of cirrus, translucent and opaque dust in the high-latitude area of LDN 1642

Authors: K. Mattila (1), P. Väisänen (2 and 3), K. Lehtinen (1), L. Haikala (4), M. Haas (5) ((1) Department of Physics, University of Helsinki, (2) South African Astronomical Observatory, Cape Town, (3) Southern African Large Telescope, Cape Town, (4) Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copiapo, (5) Astronomisches Institut, Ruhr-Universität Bochum)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.16467
Pdf link: https://arxiv.org/pdf/2306.16467
Abstract
We have performed a 5-colour surface photometric study of the high-galactic-latitude area of dark nebula LDN 1642. Scattered light properties are presented of diffuse, translucent and opaque dust over the range of 3500 -- 5500 A. Far infrared absolute photometry at 200 um improves the precision of and provides a zero point to the extinction. The intensity of the scattered light depends on dust column density in a characteristic way: for optically thin dust the intensity first increases linearly, then turns to a saturation value; at still larger extinctions the intensity turns down to a slow decrease. The $A_V$ value of the saturated intensity maximum shifts in a systematic way, from $A_V\approx$ 1.5 mag at 3500 A, to $\sim 3$ mag at 5500 A. The intensity curves offer a straight-forward explanation for the behaviour of the scattered-light colours. At the intensity peak the colour agrees with the integrated starlight colour, while it is bluer at the low- and redder at the high-column-density side of the peak, respectively. These colour changes are a direct consequence of the wavelength dependence of the extinction. We have compared the colours of the LDN 1642 area with other relevant observational studies: high-latitude diffuse/translucent clouds, wide-field cirrus dust; and externally illuminated AGB-star envelopes. For extragalactic low-surface-brightness sources cirrus is an unwanted foreground contaminant. Our results for cirrus colours can help to distinguish cases where a diffuse plume or stream, apparently associated with a galaxy or a group or cluster, is more likely a local cirrus structure. Keywords: ISM: dust, extinction -- ISM: clouds, individual LDN 1642 -- Galaxy: solar neighbourhood -- Astronomical instruments, methods and techniques: methods -- Physical data and processes: scattering

Spectroscopic comparative study of the red giant binary system gamma Leonis A and B

Authors: Yoichi Takeda
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.16723
Pdf link: https://arxiv.org/pdf/2306.16723
Abstract
Gamma~Leo is a long-period visual binary system consisting of K0III (A) and G7III (B) giants, in which particular interest is attracted by the brighter A since the discovery of a planet around it. While detailed spectroscopic comparative study of both components would be worthwhile (e.g., for probing any impact of planet formation on chemical abundances), such a research seems to have been barely attempted as most available studies tend to be biased toward A. Given this situation, the physical properties of A and B along with their differences were investigated based on high-dispersion spectra in order to establish their stellar parameters, evolutionary status, and surface chemical compositions. The following results were obtained. (1) The masses were derived as ~1.7Msun and ~1.6Msun for A and B, respectively, both of which are likely to be in the stage of red clump giants after He-ignition. The mass of the planet around A has also been revised as m*sin(i) = 10.7M_Jupiter (increased by ~~20%). (2) These are normal giants of subsolar metallicity ([Fe/H]~~-0.4) belonging to the thin-disk population. (3) A as well as B show moderate C deficiency and N enrichment, which are in compatible with the prediction from the standard stellar evolution theory. (4) The chemical abundances of 26 elements are practically the same within <~0.1dex for both components, which implies that the surface chemistry is not appreciably affected by the existence of a planet in A.

A Dynamically Distinct Stellar Population in the Leading Arm of the Sagittarius Stream

Authors: Gwibong Kang, Young Sun Lee, Young Kwang Kim, Timothy C. Beers
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.16748
Pdf link: https://arxiv.org/pdf/2306.16748
Abstract
We present a chemical and dynamical analysis of the leading arm (LA) and trailing arm (TA) of the Sagittarius (Sgr) stream, as well as for the Sgr dwarf galaxy core (SC), using red giant branch, main sequence, and RR Lyrae stars from large spectroscopic survey data. The different chemical properties among the LA, TA, and SC generally agree with recent studies, and can be understood by radial metallicity gradient established in the progenitor of the Sgr dwarf, followed by preferential stellar stripping from the outer part of the Sgr progenitor. One striking finding is a relatively larger fraction of low-eccentricity stars (e < 0.4) in the LA than in the TA and SC. The TA and SC exhibit very similar distributions. Considering that a tidal tail stripped off from a dwarf galaxy maintains the orbital properties of its progenitor, we expect that the e-distribution of the LA should be similar to that of the TA and SC. Thus, the disparate behavior of the e-distribution of the LA is of particular interest. Following the analysis of Vasiliev et al., we attempt to explain the different e-distribution by introducing a time-dependent perturbation of the Milky Way by the Large Magellanic Cloud (LMC)'s gravitational pull, resulting in substantial evolution of the angular momentum of the LA stars to produce the low-e stars. In addition, we confirm from RR Lyrae stars with high eccentricity (e > 0.6) that the TA stars farther away from the SC are also affected by disturbances from the LMC.

Neutrino flares of radio blazars observed from TeV to PeV

Authors: Alisa Suray, Sergey Troitsky
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.16797
Pdf link: https://arxiv.org/pdf/2306.16797
Abstract
Radio blazars have been linked both to individual high-energy neutrino events and to excesses in likelihood sky maps constructed from lower-energy neutrino data. However, the exact mechanism by which neutrinos are produced in these sources is still unknown. Here, we demonstrate that IceCube neutrinos with energies over 200 TeV, which were previously associated with bright radio blazars, are significantly more likely to be accompanied by flares of lower-energy events, compared to those lacking blazar counterparts. The parsec-scale core radio flux of blazars positioned within the error regions of energetic events is strongly correlated with the likelihood of a coincident day-scale lower-energy neutrino flare reported by IceCube. The probability of a chance correlation is 3.6*10^{-4}. This confirms the neutrino-blazar connection in a new and independent way, and provides valuable clues to understanding the origin of astrophysical neutrinos.

Gravitational collapse and accretion flows in the hub filament system G323.46-0.08

Authors: Yingxiu Ma, Jianjun Zhou, Jarken Esimbek, Willem Baan, Dalei Li, Xindi Tang, Yuxin He, Weiguang Ji, Dongdong Zhou, Gang Wu, Kadirya Tursun, Toktarkhan Komesh
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.16875
Pdf link: https://arxiv.org/pdf/2306.16875
Abstract
We studied the hub filament system G323.46-0.08 based on archival molecular line data from the SEDIGISM 13CO survey and infrared data from the GLIMPSE, MIPS, and Hi-GAL surveys. G323.46-0.08 consists of three filaments, F-north, F-west, and F-south, that converge toward the central high_mass clump AGAL 323.459-0.079. F-west and Part 1 of the F-south show clear large-scale velocity gradients 0.28 and 0.44 km s-1 pc-1, respectively. They seem to be channeling materials into AGAL 323.459-0.079. The minimum accretion rate was estimated to be 1216 M Myr-1. A characteristic V-shape appears around AGAL 323.459-0.079 in the PV diagram, which traces the accelerated gas motions under gravitational collapse. This has also been supported by model fitting results. All three filaments are supercritical and they have fragmented into many dense clumps. The seesaw patterns near most dense clumps in the PV diagram suggests that mass accretion also occurs along the filament toward the clumps. Our results show that filamentary accretion flows appear to be an important mechanism for supplying the materials necessary to form the central high-mass clump AGAL 323.459-0.079 and to propel the star forming activity taking place therein.

Cross section for supernova axion observation in neutrino water Cherenkov detectors

Authors: Pierluca Carenza, Giampaolo Co', Maurizio Giannotti, Alessandro Lella, Giuseppe Lucente, Alessandro Mirizzi, Thomas Rauscher
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
Arxiv link: https://arxiv.org/abs/2306.17055
Pdf link: https://arxiv.org/pdf/2306.17055
Abstract
Axions coupled to nucleons might be copiously emitted from core-collapse supernovae (SNe). If the axion-nucleon coupling is strong enough, axions would be emitted from the SN as a burst and, reaching Earth, may excite the oxygen nuclei in water Cherenkov detectors (${}^{16}{\rm O} + a \to {}^{16}{\rm O}^{}$). This process will be followed by radiative decay(s) of the excited state (${}^{16}{\rm O}^ \rightarrow {}^{16}{\rm O}+\gamma $) providing a strategy for a direct detection of axions from a Galactic SN in large underground neutrino Cherenkov detectors. Motivated by this possibility, we present an updated calculation of axion-oxygen cross section obtained by using self-consistent continuum Random Phase Approximation. We calculate the branching ratio of the oxygen nucleus de-excitation into gamma-rays, neutrons, protons and $\alpha$-particles. These results are used to revisit the detectability of axions from SN 1987A in Kamiokande-II.

A rare outburst from the stealthy BeXRB system Swift J0549.7-6812

Authors: M.J. Coe (Southampton), J.A. Kennea (PSU), I.M. Monageng (UCT), D.A.H. Buckley (SAAO), A. Udalski (Warsaw), P.A. Evans (Leicester)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.17098
Pdf link: https://arxiv.org/pdf/2306.17098
Abstract
Swift J0549.7-6812 is an Be/X-ray binary system (BeXRB) in the Large Magellanic Cloud (LMC) exhibiting a 6s pulse period. Like many such systems the variable X-ray emission is believed to be driven by the underlying behaviour of the mass donor Be star. In this paper we report on X-ray observations of the brightest known outburst from this system which reached a luminosity of 8 x 10^37 erg/s. These observations are supported by contemporaneous optical photometric observations, the first reported optical spectrum, as well as several years of historical data from OGLE and GAIA. The latter strongly suggest a binary period of 46.1d. All the observational data indicate that Swift J0549.7-6812 is a system that spends the vast majority of its time in X-ray quiescence, or even switched off completely. This suggests that occasional observations may easily miss it, and many similar systems, and thereby underestimate the massive star evolution numbers for the LMC.

by olozhika (Xing Yuchen).

2023-06-30

New submissions for Thu, 11 May 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.
2023-05-11

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Today: 12papers

(433) Eros and (25143) Itokawa surface properties from reflectance spectra

Authors: David Korda, Tomáš Kohout, Kateřina Flanderová, Jean-Baptiste Vincent, Antti Penttilä
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.05700
Pdf link: https://arxiv.org/pdf/2305.05700
Abstract
Context. Upcoming space missions will provide us with surface-resolved NEA reflectance spectra. Neural networks are useful tools for analysing reflectance spectra and determining material composition with high precision and low processing time. Aims. We applied neural-network models on disk-resolved spectra of the Eros and Itokawa asteroids observed by the NEAR Shoemaker and Hayabusa spacecraft. With this approach, the mineral variations or intensity of space weathering can be mapped. Methods. We tested two types of convolutional neural networks. The first one was trained using asteroid reflectance spectra with known taxonomy classes. The other one used silicate reflectance spectra with assigned mineral abundances and compositions. Results. The reliability of the classification model depends on the resolution of reflectance spectra. Typical F1 score and Cohen's ${\kappa}_C$ values decrease from about 0.90 for high-resolution spectra to about 0.70 for low-resolution spectra. The predicted silicate composition does not strongly depend on spectrum resolution and coverage of the 2${\mu}$m band of pyroxene. The typical root mean square error is between 6 and 10 percentage points. For the Eros and Itokawa asteroids, the predicted taxonomy classes favour the S-type and the predicted surface compositions are homogeneous and correspond to the composition of L/LL and LL ordinary chondrites, respectively. On the Itokawa surface, the model identified fresh spots that were connected with craters or coarse-grain areas. Conclusions. The neural network models trained with measured spectra of asteroids and silicate samples are suitable for deriving surface silicate mineralogy with a reasonable level of accuracy. The predicted surface mineralogy is comparable to the mineralogy of returned samples measured in the laboratory. Moreover, the taxonomical predictions can point out locations of fresher areas.

NGC 1436: the making of a lenticular galaxy in the Fornax cluster

Authors: Alessandro Loni, Paolo Serra, Marc Sarzi, Gyula I. G. Józsa, Pablo M. Galán-de Anta, Nikki Zabel, Dane Kleiner, Filippo M. Maccagni, Daniel Molnár, Mpati Ramatsoku, Francesca Loi, Enrico M. Corsini, D. J. Pisano, Peter Kamphuis, Timothy A. Davis, W. J. G. de Blok, Ralf J. Dettmar, Jesus Falcon-Barroso, Enrichetta Iodice, Maritza A. Lara-López, S. Ilani Loubser, Kana Morokuma-Matsui, Reynier Peletier, Francesca Pinna, Adriano Poci, Matthew W. L. Smith, Scott C. Trager, Glenn van de Ven
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.05709
Pdf link: https://arxiv.org/pdf/2305.05709
Abstract
We study the evolutionary path of the Fornax cluster galaxy NGC$$1436, which is known to be currently transitioning from a spiral into a lenticular morphology. This galaxy hosts an inner star-forming disc and an outer quiescent disc, and we analyse data from the MeerKAT Fornax Survey, ALMA, and the Fornax3D survey to study the interstellar medium and the stellar populations of both disc components. Thanks to the combination of high resolution and sensitivity of the MeerKAT data, we find that the $\textrm{H}\scriptstyle\mathrm{I}$ is entirely confined within the inner star-forming disc, and that its kinematics is coincident with that of the CO. The cold gas disc is now well settled, which suggests that the galaxy has not been affected by any environmental interactions in the last $\sim1$Gyr. The star formation history derived from the Fornax3D data shows that both the inner and outer disc experienced a burst of star formation $\sim5$ Gyr ago, followed by rapid quenching in the outer disc and by slow quenching in the inner disc, which continues forming stars to this day. We claim that NGC$~~$1436 has begun to effectively interact with the cluster environment 5$~~$Gyr ago, when a combination of gravitational and hydrodynamical interactions caused the temporary enhancement of the star-formation rate. Furthermore, due to the weaker gravitational binding $\textrm{H}\scriptstyle\mathrm{I}$ was stripped from the outer disc, causing its rapid quenching. At the same time, accretion of gas onto the inner disc stopped, causing slow quenching in this region.

Physics and Chemistry of Radiation Driven Cloud Evolution. [C II] Kinematics of IC 59 and IC 63

Authors: Miranda Caputo, Archana Soam, B-G Andersson, Remy Dennis, Ed Chambers, Rolf Güsten, Lewis B.G. Knee, Jürgen Stutzki
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.05719
Pdf link: https://arxiv.org/pdf/2305.05719
Abstract
We used high-resolution [C II] 158 $\mu$m mapping of two nebulae IC 59 and IC 63 from SOFIA/upGREAT in conjunction with ancillary data on the gas, dust, and polarization to probe the kinematics, structure, and magnetic properties of their photo-dissociation regions (PDRs). The nebulae are part of the Sh 2-185 H II region illuminated by the B0 IVe star $\gamma$ Cas. The velocity structure of each PDR changes with distance from $\gamma$ Cas, consistent with driving by the radiation. Based on previous FUV flux measurements of, and the known distance to $\gamma$ Cas along with the predictions of 3D distances to the clouds, we estimated the FUV radiation field strength (G0) at the clouds. Assuming negligible extinction between the star and clouds, we find their 3D distances from $\gamma$ Cas. For IC 63, our results are consistent with earlier estimates of distance from Andersson et al. (2013), locating the cloud at 2 pc from $\gamma$ Cas, at an angle of 58 to the plane of the sky, behind the star. For IC 59, we derive a distance of 4.5 pc at an angle of 70 in front of the star. We do not detect any significant correlation between the orientation of the magnetic field (Soam et al. 2017) and the velocity gradients of [C II] gas, indicating a moderate magnetic field strength. The kinetic energy in IC 63 is estimated to be order of ten higher than the magnetic energies. This suggests that kinetic pressure in this nebula is dominant.

Case A or Case B? The effective recombination coefficient in gas clouds of arbitrary optical thickness

Authors: Olof Nebrin
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2305.05764
Pdf link: https://arxiv.org/pdf/2305.05764
Abstract
In calculations of the ionization state, one is often forced to choose between the Case A recombination coefficient $\alpha_{\rm A}$ (sum over recombinations to all hydrogen states) or the Case B recombination coefficient $\alpha_{\rm B}$ (sum over all hydrogen states except the ground state). If the cloud is optically thick to ionizing photons, $\alpha_{\rm B}$ is usually adopted on the basis of the "on-the-spot" approximation, wherein recombinations to the ground state are ignored because they produce ionizing photons absorbed nearby. In the opposite case of an optically thin cloud, one would expect the Case A recombination coefficient to better describe the effective recombination rate in the cloud. In this paper, I derive an analytical expression for the effective recombination coefficient in a gas cloud of arbitrary optical thickness which transitions from $\alpha_{\rm A}$ to $\alpha_{\rm B}$ as the optical thickness increases. The results can be readily implemented in numerical simulations and semi-analytical calculations.

Inferences from surface brightness fluctuations of Zwicky 3146 via the Sunyaev-Zeldovich effect and X-ray observations

Authors: Charles E. Romero, Massimo Gaspari, Gerrit Schellenberger, Tanay Bhandarkar, Mark Devlin, Simon R. Dicker, William Forman, Rishi Khatri, Ralph Kraft, Luca Di Mascolo, Brian S. Mason, Emily Moravec, Tony Mroczkowski, Paul Nulsen, John Orlowski-Scherer, Karen Perez Sarmiento, Craig Sarazin, Jonathan Sievers, Yuanyuan Su
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Arxiv link: https://arxiv.org/abs/2305.05790
Pdf link: https://arxiv.org/pdf/2305.05790
Abstract
The galaxy cluster Zwicky 3146 is a sloshing cool core cluster at $z{=}0.291$ that in SZ imaging does not appear to exhibit significant pressure substructure in the intracluster medium (ICM). We perform a surface brightness fluctuation analysis via Fourier amplitude spectra on SZ (MUSTANG-2) and X-ray (XMM-Newton) images of this cluster. These surface brightness fluctuations can be deprojected to infer pressure and density fluctuations from the SZ and X-ray data, respectively. In the central region (Ring 1, $r < 100^{\prime\prime} = 440$ kpc, in our analysis) we find fluctuation spectra that suggest injection scales around 200 kpc ($\sim 140$ kpc from pressure fluctuations and $\sim 250$ kpc from density fluctuations). When comparing the pressure and density fluctuations in the central region, we observe a change in the effective thermodynamic state from large to small scales, from isobaric (likely due to the slow sloshing) to adiabatic (due to more vigorous motions). By leveraging scalings from hydrodynamical simulations, we find an average 3D Mach number $\approx0.5$. We further compare our results to other studies of Zwicky 3146 and, more broadly, to other studies of fluctuations in other clusters.

1100 Days in the Life of the Supernova 2018ibb -- the Best Pair-Instability Supernova Candidate, to date

Authors: Steve Schulze, Claes Fransson, Alexandra Kozyreva, Ting-Wan Chen, Ofer Yaron, Anders Jerkstrand, Avishay Gal-Yam, Jesper Sollerman, Lin Yan, Tuomas Kangas, Giorgos Leloudas, Conor M. B. Omand, Stephen J. Smartt, Yi Yang, Matt Nicholl, Nikhil Sarin, Yuhan Yao, Thomas G. Brink, Amir Sharon, Andrea Rossi, Ping Chen, Zhihao Chen, Aleksandar Cikota, Kishalay De, Andrew J. Drake, Alexei V. Filippenko, Christoffer Fremling, Laurane Freour, Johan P. U. Fynbo, Anna Y. Q. Ho, Cosimo Inserra, Ido Irani, Hanindyo Kuncarayakti, Ragnhild Lunnan, Paolo Mazzali, Eran O. Ofek, Eliana Palazzi, Daniel A. Perley, Miika Pursiainen, Barry Rothberg, Luke J. Shingles, Ken Smith, Kirsty Taggart, Leonardo Tartaglia, WeiKang Zheng, Joseph P. Anderson, Letizia Cassara, Eric Christensen, S. George Djorgovski, Lluis Galbany, et al. (16 additional authors not shown)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.05796
Pdf link: https://arxiv.org/pdf/2305.05796
Abstract
Abridged - Stars with ZAMS masses between 140 and $260 M_\odot$ are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up to several tens of solar masses of radioactive nickel, resulting in luminous transients similar to some superluminous supernovae (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN2018ibb is a H-poor SLSN at $z=0.166$ that evolves extremely slowly compared to the hundreds of known SLSNe. Between mid 2018 and early 2022, we monitored its photometric and spectroscopic evolution from the UV to the NIR with 2-10m class telescopes. SN2018ibb radiated $>3\times10^{51} \rm erg$ during its evolution, and its bolometric light curve reached $>2\times10^{44} \rm erg,s^{-1}$ at peak. The long-lasting rise of $>93$ rest-frame days implies a long diffusion time, which requires a very high total ejected mass. The PISN mechanism naturally provides both the energy source ($^{56}$Ni) and the long diffusion time. Theoretical models of PISNe make clear predictions for their photometric and spectroscopic properties. SN2018ibb complies with most tests on the light curves, nebular spectra and host galaxy, potentially all tests with the interpretation we propose. Both the light curve and the spectra require 25-44 $M_\odot$ of freshly nucleosynthesised $^{56}$Ni, pointing to the explosion of a metal-poor star with a He-core mass of 120-130 $M_\odot$ at the time of death. This interpretation is also supported by the tentative detection of [Co II]$\lambda$1.025$\mu$m, which has never been observed in any other PISN candidate or SLSN before. Powering by a central engine, such as a magnetar or a black hole, can be excluded with high confidence. This makes SN2018ibb by far the best candidate for being a PISN, to date.

A 3D physico-chemical model of a pre-stellar core. I. Environmental and structural impact on the distribution of CH$_3$OH and $c$-C$_3$H$_2$

Authors: S. S. Jensen, S. Spezzano, P. Caselli, T. Grassi, T. Haugbølle
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.05932
Pdf link: https://arxiv.org/pdf/2305.05932
Abstract
Pre-stellar cores represent the earliest stage of the star- and planet-formation process. By characterizing the physical and chemical structure of these cores we can establish the initial conditions for star and planet formation and determine to what degree the chemical composition of pre-stellar cores is inherited to the later stages. A 3D MHD model of a pre-stellar core embedded in a dynamic star-forming cloud is post-processed using sequentially continuum radiative transfer, a gas-grain chemical model, and a line-radiative transfer model. Results are analyzed and compared to observations of CH$_3$OH and $c$-C$_3$H$_2$ in L1544. Nine different chemical models are compared to the observations to determine which initial conditions are compatible with the observed chemical segregation in the prototypical pre-stellar core L1544. The model is able to reproduce several aspects of the observed chemical differentiation in L1544. Extended methanol emission is shifted towards colder and more shielded regions of the core envelope while $c$-C$_3$H$_2$ emission overlaps with the dust continuum, consistent with the observed chemical structure. Increasing the strength of the interstellar radiation field or the cosmic-ray ionization rate with respect to the typical values assumed in nearby star-forming regions leads to synthetic maps that are inconsistent with the observed chemical structure. Our model shows that the observed chemical dichotomy in L1544 can arise as a result of uneven illumination due to the asymmetrical structure of the 3D core and the environment within which the core has formed. This highlights the importance of the 3D structure at the core-cloud transition on the chemistry of pre-stellar cores.

Temperature and density dependence of line profiles of sodium perturbed by helium

Authors: N. F. Allard, K. Myneni, J. N. Blakely, G. Guillon
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.06079
Pdf link: https://arxiv.org/pdf/2305.06079
Abstract
Ultracool stellar atmospheres show absorption by alkali resonance lines severely broadened by collisions with neutral perturbers. In the coolest and densest atmospheres, such as those of T dwarfs, Na I and K I broadened by molecular hydrogen and helium can come to dominate the entire optical spectrum. The effects of NaHe collision broadening are also central to understanding the opacity of cool DZ white dwarf stars. In order to be able to construct synthetic spectra of brown dwarfs and cool DZ white dwarfs, where helium density can reach several 10^21cm-3 NaHe line profiles of the resonance lines have been computed over a wide range of densities and temperatures. Unified line profiles that are valid from the core to the far wings at high densities are calculated in the semiclassical approach using up-to-date molecular data including in particular electronic spin-orbit coupling from the sodium atom. We present a comprehensive study of Na-He collisional profiles at high density, and temperatures from 5000K, the temperature prevailing in the atmosphere of ultra-cool DZ white dwarf stars, down to 1~K, the temperature in liquid helium clusters. Collision broadening and shift parameters within the impact approximation obtained in the semiclassical and quantum theory using our new accurate molecular data are presented.

Multi-Messenger Diagnostics of the Engine behind Core-Collapse Supernovae

Authors: Christopher L. Fryer, Eric Burns, Aimee Hungerford, Samar Safi-Harb, R.T. Wollaeger, Richard S. Miller, Michela Negro, Samalka Anandagoda, Dieter H. Hartmann
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.06134
Pdf link: https://arxiv.org/pdf/2305.06134
Abstract
Core-collapse supernova explosions play a wide role in astrophysics by producing compact remnants (neutron stars, black holes) and the synthesis and injection of many heavy elements into their host Galaxy. Because they are produced in some of the most extreme conditions in the universe, they can also probe physics in extreme conditions (matter at nuclear densities and extreme temperatures and magnetic fields). To quantify the impact of supernovae on both fundamental physics and our understanding of the Universe, we must leverage a broad set of observables of this engine. In this paper, we study a subset of these probes using a suite of 1-dimensional, parameterized mixing models: ejecta remnants from supernovae, ultraviolet, optical and infra-red lightcurves, and transient gamma-ray emission. We review the other diagnostics and show how the different probes tie together to provide a more clear picture of the supernova engine.

A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

Authors: Eliza M.-R. Kempton, Michael Zhang, Jacob L. Bean, Maria E. Steinrueck, Anjali A. A. Piette, Vivien Parmentier, Isaac Malsky, Michael T. Roman, Emily Rauscher, Peter Gao, Taylor J. Bell, Qiao Xue, Jake Taylor, Arjun B. Savel, Kenneth E. Arnold, Matthew C. Nixon, Kevin B. Stevenson, Megan Mansfield, Sarah Kendrew, Sebastian Zieba, Elsa Ducrot, Achrène Dyrek, Pierre-Olivier Lagage, Keivan G. Stassun, Gregory W. Henry, Travis Barman, Roxana Lupu, Matej Malik, Tiffany Kataria, Jegug Ih, Guangwei Fu, Luis Welbanks, Peter McGill
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2305.06240
Pdf link: https://arxiv.org/pdf/2305.06240
Abstract
There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars. Population statistics show that close-in planets in this size range bifurcate into two classes based on their radii. It is hypothesized that the group with larger radii (referred to as "sub-Neptunes") is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet's atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with JWST in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 $\pm$ 9 and 437 $\pm$ 19 K, respectively) each show >3$\sigma$ evidence of absorption features, with H$_2$O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b's Bond albedo is 0.51 $\pm$ 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.

Jet-powered turbulence in common envelope evolution

Authors: Shlomi Hillel, Ron Schreier, Noam Soker (Technion, Israel)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2305.06266
Pdf link: https://arxiv.org/pdf/2305.06266
Abstract
We conduct a three-dimensional hydrodynamical simulation of a common envelope evolution (CEE) where a neutron star (NS) spirals-in inside the envelope of a red supergiant (RSG) star in a predetermined orbit. We find that the jets shed pairs of vortices in an expanding spiral pattern, inflate two expanding spirally-shaped low-density bubbles, one above and one below the equatorial plane, and deposit angular momentum to the envelope. In the simulation we do not include the gravity of the NS such that all effects we find are solely due to the jets that the spiralling-in NS launches. The angular momentum that the jets deposit to the envelope is of the same order of magnitude as the orbital angular momentum and has the same direction. The turbulence that the jets induce in the common envelope might play a role in transporting energy and angular momentum. The jet-deposited energy that is radiated away (a process not studied here) leads to a transient event that is termed common envelope jets supernova (CEJSN) and might mimic an energetic core collapse supernova. The turbulence and the spiral pattern that we explore here might lead to bumps in the late light curve of the CEJSN when different segments of the ejected envelope collide with each other. This study emphasises the roles that jets can play in CEE (including jets launched by black hole companions) and adds to the rich variety of processes in CEJSN events.

3D evolution of neutron star magnetic-fields from a realistic core-collapse turbulent topology

Authors: Clara Dehman, Daniele Viganò, Stefano Ascenzi, Jose A. Pons, Nanda Rea
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2305.06342
Pdf link: https://arxiv.org/pdf/2305.06342
Abstract
We present the first 3D fully coupled magneto-thermal simulations of neutron stars (including the most realistic background structure and microphysical ingredients so far) applied to a very complex initial magnetic field topology in the crust, similar to what recently obtained by proto-neutron star dynamo simulations. In such configurations, most of the energy is stored in the toroidal field, while the dipolar component is a few percent of the mean magnetic field. This initial feature is maintained during the long-term evolution (1e6 yr), since the Hall term favours a direct cascade (compensating for Ohmic dissipation) rather than a strong inverse cascade, for such an initial field topology. The surface dipolar component, responsible for the dominant electromagnetic spin-down torque, does not show any increase in time, when starting from this complex initial topology. This is at contrast with the timing properties of young pulsars and magnetars which point to higher values of the surface dipolar fields. A possibility is that the deep-seated magnetic field (currents in the core) is able to self-organize in large scales (during the collapse or in the early life of a neutron star). Alternatively, the dipolar field might be lower than is usually thought, with magnetosphere substantially contributing to the observed high spin-down, via e.g., strong winds or strong coronal magnetic loops, which can also provide a natural explanation to the tiny surface hotspots inferred from X-ray data.

New submissions for Thu, 22 Jun 23

Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.

Forked from zhuhu00/Paper-Daily-Notice.

Keyword list: ['star formation', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']

Excluded: ['galaxies', 'galaxy cluster', 'AGN']

Today: 12papers

A calibration point for stellar evolution from massive star asteroseismology

Authors: Siemen Burssens, Dominic M. Bowman, Mathias Michielsen, Sergio Simón-Díaz, Conny Aerts, Vincent Vanlaer, Gareth Banyard, Nicolas Nardetto, Richard H. D. Townsend, Gerald Handler, Joey S. G. Mombarg, Roland Vanderspek, George Ricker
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.11798
Pdf link: https://arxiv.org/pdf/2306.11798
Abstract
Massive stars are progenitors of supernovae, neutron stars and black holes. During the hydrogen-core burning phase their convective cores are the prime drivers of their evolution, but inferences of core masses are subject to unconstrained boundary mixing processes. Moreover, uncalibrated transport mechanisms can lead to strong envelope mixing and differential radial rotation. Ascertaining the efficiency of the transport mechanisms is challenging because of a lack of observational constraints. Here we deduce the convective core mass and robustly demonstrate non-rigid radial rotation in a supernova progenitor, the $12.0^{+1.5}{-1.5}$ solar-mass hydrogen-burning star HD 192575, using asteroseismology, TESS photometry, high-resolution spectroscopy, and Gaia astrometry. We infer a convective core mass ($M{\rm cc} = 2.9^{+0.5}_{-0.8}$ solar masses), and find the core to be rotating between 1.4 and 6.3 times faster than the stellar envelope depending on the location of the rotational shear layer. Our results deliver a robust inferred core mass of a massive star using asteroseismology from space-based photometry. HD 192575 is a unique anchor point for studying interior rotation and mixing processes, and thus also angular momentum transport mechanisms inside massive stars.

A Venus in the Making? Predictions for JWST Observations of the Ultracool M-Dwarf planet LP 890-9 c

Authors: Jonathan Gomez Barrientos, Lisa Kaltenegger, Ryan J. MacDonald
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.11826
Pdf link: https://arxiv.org/pdf/2306.11826
Abstract
The recently discovered transiting super-Earth LP 890-9 c is potentially one of the best rocky exoplanets for atmospheric characterization. Orbiting an ultracool M-dwarf at the inner edge of the habitable zone, LP 890-9 c offers a new opportunity to study the climate of rocky planets at the inner edge of the habitable zone. We investigate the molecular detectability with simulated JWST transmission spectra for five potential atmospheres of LP 890-9 c. We find that a small three-transit JWST program can infer evidence of H2O (at 3$\sigma$ confidence) for a full runaway greenhouse scenario. Alternatively, CO2-dominated atmospheres resembling Venus without high-altitude terminator clouds can be identified with eight transits. However, these predictions could be complicated by the impact of clouds and/or unocculted starspots. Nevertheless, JWST observations of LP 890-9 c could provide critical insights and potentially distinguish between models of rocky planets at the inner edge of the habitable zone.

Evidence for a gamma-ray molecular target in the enigmatic PeVatron candidate LHAASO J2108+5157

Authors: E. de la Fuente, I. Toledano-Juárez, K. Kawata, M. A. Trinidad, M. Yamagishi, S. Takekawa, D. Tafoya, M. Ohnishi, A. Nishimura, S. Kato, T.Sako, M. Takita, H. Sano, R. K. Yadav
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.11921
Pdf link: https://arxiv.org/pdf/2306.11921
Abstract
To determine the nature of the PeVatron's emission (hadronic or leptonic), it is essential to characterize the physical parameters of the environment from where it originates. We unambiguously confirm the association of molecular gas with the PeVatron candidate LHAASO J2108+5157 using unprecedented high angular-resolution (17$^{\prime \prime}$) $^{12,13}$CO($J$=1$\rightarrow$0) observations carried out with the Nobeyama 45m radio telescope. We characterize a molecular cloud in the vicinity of the PeVatron candidate LHAASO J2108+5157 by determining its physical parameters from our $^{12,13}$CO($J$=1$\rightarrow$0) line observations. We use an updated estimation of the distance to the cloud, which allows us to obtain a more reliable result. The molecular emission is compared with excess gamma-ray images obtained with Fermi--LAT at energies above 2 GeV to search for spatial correlations and test a possible hadronic ($\pi^0$ decay) origin for the gamma-ray emission. We find that the morphology of the spatial distribution of the CO emission is strikingly similar to that of the Fermi--LAT excess gamma-ray. By combining our observations with archival 21cm HI line data, the nucleons (HI + H$_2$) number density of the target molecular cloud is found to be 133.0 $\pm$ 45.0 cm$^{-3}$, for the measured angular size of 0.55 $\pm$ 0.02$^\circ$ at a distance of 1.6 $\pm$ 0.1 kpc. The resulting total mass of the cloud is M(HI +H$2$) = 7.5$\pm$2.9$\times$10$^3$ M${\odot}$. Under a hadronic scenario, we obtain a total energy of protons of W$_p$ = 4.3$\pm$1.5 $\times$ 10$^{46}$ erg with a cutoff of 700$\pm$300 TeV, which reproduces the sub-PeV gamma-ray emission. We identified a molecular cloud in the vicinity of LHAASO J2107+5157 as the main target where cosmic rays from an unknown PeVatron produce the observed gamma-ray emission via $\pi^0$ decay.

Modeling of the nebular-phase spectral evolution of stripped-envelope supernovae. New grids from 100 to 450 days

Authors: Luc Dessart, D. John Hillier, S. E. Woosley, Hanindyo Kuncarayakti
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Arxiv link: https://arxiv.org/abs/2306.12092
Pdf link: https://arxiv.org/pdf/2306.12092
Abstract
We present an extended grid of multi-epoch 1D nonlocal thermodynamic equilibrium radiative transfer calculations for nebular-phase Type Ibc supernovae (SNe) from He-star explosions. Compared to Dessart+21, we study the spectral evolution from 100 to about 450d and augment the model set with progenitors that were evolved without wind mass loss. Models with the same final, preSN mass have similar yields and produce essentially the same emergent spectra. Hence, the uncertain progenitor mass loss history compromises the inference of the initial, main sequence mass. This shortcoming does not affect Type IIb SNe. However, our 1D models with a different preSN mass tend to yield widely different spectra, as seen through variations in the strong emission lines due to [NII]6548-6583, [OI]6300-6364, [CaII]7291-7323, [NiII]7378, and the forest of FeII lines below 5500A. At the lower mass end, the ejecta are He rich and at 100d cool through HeI, NII, CaII, and FeII lines, with NII and FeII dominating at 450d. These models, associated with He giants, conflict with observed SNe Ib, which typically lack strong NII emission. Instead they may lead to SNe Ibn or, because of additional stripping by a companion star, ultra-stripped SNe Ic. In contrast, for higher preSN masses, the ejecta are progressively He poor and cool at 100d through OI, CaII, and FeII lines, with OI and CaII dominating at 450d. Nonuniform, aspherical, large-scale mixing rather than composition differences likely determines the SN type at intermediate preSN masses. Variations in clumping, mixing, as well as departures from spherical symmetry would increase the spectral diversity but also introduce additional degeneracies. More robust predictions from spectral modeling require a careful attention to the initial conditions informed by physically-consistent 3D explosion models [abridged].

Generation of high circular polarization of interstellar Lyman $α$ radiation triggering biological homochirality

Authors: Hajime Fukushima, Hidenobu Yajima, Masayuki Umemura
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12101
Pdf link: https://arxiv.org/pdf/2306.12101
Abstract
The homochirality of biological molecules on the Earth is a long-standing mystery regarding the origin of life. Circularly polarized ultraviolet (UV) light could induce the enantiomeric excess of biological molecules in the interstellar medium, leading to the homochirality on the earth. By performing 3D radiation transfer simulations with multiple scattering processes in interstellar dusty slabs, we study the generation of circular polarization (CP) of ultraviolet light at Lyman $\alpha$ ($\lambda = 0.1216~{\rm \mu m}$) as well as in the near-infrared (NIR, $\lambda = 2.14~{\rm \mu m}$) wavelengths. Our simulations show that the distributions of CP exhibit a symmetric quadrupole pattern, regardless of wavelength and viewing angle. The CP degree of scattered light from a dusty slab composed of aligned grains is $\sim 15$ percent for Ly$\alpha$ and $\sim 3$ percent at NIR wavelengths in the case of oblate grains with an MRN size distribution. We find that the CP degree of Ly$\alpha$ is well correlated with that in the NIR regardless of viewing angles, whilst being a factor of $\sim 5$ higher. Thus, high CP of Ly$\alpha$ is expected in sites where NIR CP is detected. We suggest that such circularly polarized Ly$\alpha$ may initiate the enantiomeric excess of biological molecules in space.

Spatial distributions and kinematics of shocked and ionized gas in M17

Authors: Feng-Yao Zhu, Junzhi Wang, Yaoting Yan, Qing-Feng Zhu, Juan Li
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12128
Pdf link: https://arxiv.org/pdf/2306.12128
Abstract
Massive stars are formed in molecular clouds, and produce H II regions when they evolve onto the main sequence. The expansion of H II region can both suppress and promote star formation in the vicinity. M17 H II region is a giant cometary H II region near many massive clumps containing starless and protostellar sources. It is an appropriate target to study the effect of feedback from previously formed massive stars on the nearby star-forming environments. Observations of SiO 2-1, HCO$^+$ 1-0, H$^{13}$CO$^+$ 1-0, HC$_3$N 10-9, and H41$\alpha$ lines are performed toward M17 H II region with ambient candidates of massive clumps. In the observations, the widespread shocked gas surrounding M17 H II region is detected: it probably originates from the collision between the expanding ionized gas and the ambient neutral medium. Some massive clumps are found in the overlap region of the shock and dense-gas tracing lines while the central velocities of shocked and high-density gases are similar. This suggests that part of massive clumps are located in the shell of H II region, and may be formed from the accumulated neutral materials in the shell. In addition, by comparing the observations toward M17 H II region with the simulation of cometary H II region, we infer the presence of one or more massive stars travelling at supersonic velocity with respect to the natal molecular cloud in the H II region.

Origins of the shocks in high-mass starless clump candidates

Authors: Feng-Yao Zhu, Junzhi Wang, Yaoting Yan, Qing-Feng Zhu, Juan Li
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12135
Pdf link: https://arxiv.org/pdf/2306.12135
Abstract
Shocks are abundant in star-forming regions, and are often related with star formation. In our previous observations toward 100 starless clump candidates (SCCs) in the Galaxy, a sample of 34 SCCs associated with shocks is identified. In this work, we perform mapping observations of the SiO 2-1, 3-2, HC$_3$N 10-9, HCO$^+$ 1-0, H$^{13}$CO$^+$ 1-0, and H41$\alpha$ lines toward 9 out of the detected sources by using IRAM 30-m radio telescope to study the origins of the shocks in the SCCs. We find shocks in three sources (BGPS 3110, 3114, and 3118) are produced by collisions between the expanding ionized gas and ambient molecular gas, instead of by the star formation activity inside SCCs. On the other hand, shocks in the other six sources are related to star formation activity of SCCs. The signatures of protostellar outflows are clearly shown in the molecular lines toward BGPS 4029, 4472, 5064. Comparing our results with the previous ALMA observations performed in the same region, the shocks in BGPS 3686 and 5114 are also likely to be due to protostellar activity. The origin of shock in BGPS 5243 is still unclear although some features in the SiO spectra imply the presence of protostellar activity.

Cloud Behaviour on Tidally Locked Rocky Planets from Global High-resolution Modeling

Authors: Jun Yang, Yixiao Zhang, Zuntao Fu, Mingyu Yan, Xinyi Song, Mengyu Wei, Jiachen Liu, Feng Ding, Zhihong Tan
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Arxiv link: https://arxiv.org/abs/2306.12186
Pdf link: https://arxiv.org/pdf/2306.12186
Abstract
Determining the behaviour of convection and clouds is one of the biggest challenges in our understanding of exoplanetary climates. Given the lack of in situ observations, one of the most preferable approaches is to use cloud-resolving or cloud-permitting models (CPM). Here we present CPM simulations in a quasi-global domain with high spatial resolution (4$\times$4 km grid) and explicit convection to study the cloud regime of 1 to 1 tidally locked rocky planets orbiting around low-mass stars. We show that the substellar region is covered by deep convective clouds and cloud albedo increases with increasing stellar flux. The CPM produces relatively less cloud liquid water concentration, smaller cloud coverage, lower cloud albedo, and deeper H2O spectral features than previous general circulation model (GCM) simulations employing empirical convection and cloud parameterizations. Furthermore, cloud streets--long bands of low-level clouds oriented nearly parallel to the direction of the mean boundary-layer winds--appear in the CPM and substantially affect energy balance and surface precipitation at a local level.

Near infrared view on the photodissociation regions S255, S257, NGC7538 and S140

Authors: M. S. Kirsanova, A. M. Tatarnikov, P. A. Boley, D. S. Wiebe, N. A. Maslennikova, A. A. Tatarnikov
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Arxiv link: https://arxiv.org/abs/2306.12264
Pdf link: https://arxiv.org/pdf/2306.12264
Abstract
We performed photometric observations of the S255, S257, S140, NGC7358 and the Orion~Bar photo-dissociation regions (PDRs) at 2 micron using narrow-band filters centered on the Br-gamma, H2 and [FeII] lines, as well as the narrow-band Kcont and the broad-band H filters for continuum subtraction. The observations were done with the 2.5-m telescope of the SAI Caucasian Mountain Observatory and the near-infrared camera and spectrograph ASTRONIRCAM. We find several high-density arc-like structures in the Br-gamma and [FeII] images of the ionized gas in NGC7538 and extended shells and arcs visible through the H2 emission. The H ionization front and H2 dissociation front are merged in NGC7538. In S255 and S257 we detected only Br-gamma emission from the HII regions and bright H2 emission from the PDRs. The projected distance between the H ionization and H2 dissociation fronts are approx. 0.3-0.4 pc, which cannot be explained using models of a uniform medium. Most probably, the ionized and neutral gas in these PDRs is clumpy. The H-to-H2 transitions in the NGC7538, S255, S257 and S140 PDRs are gradual with no sharp borders. This conclusion also confirms the suggestion of a clumpy medium.

RomAndromeda: The Roman Survey of the Andromeda Halo

Authors: Arjun Dey, Joan Najita, Carrie Filion, Jiwon Jesse Han, Sarah Pearson, Rosemary Wyse, Adrien C. R. Thob, Borja Anguiano, Miranda Apfel, Magda Arnaboldi, Eric F. Bell, Leandro Beraldo e Silva, Gurtina Besla, Aparajito Bhattacharya, Souradeep Bhattacharya, Vedant Chandra, Yumi Choi, Michelle L. M. Collins, Emily C. Cunningham, Julianne J. Dalcanton, Ivanna Escala, Hayden R. Foote, Annette M. N. Ferguson, Benjamin J. Gibson, Oleg Y. Gnedin, Puragra Guhathakurta, Keith Hawkins, Danny Horta, Rodrigo Ibata, Nitya Kallivayalil, Eric W. Koch, Sergey Koposov, Geraint F. Lewis, Lucas Macri, Kevin A. McKinnon, David L. Nidever, Knut A.G. Olsen, Ekta Patel, Michael S. Petersen, Andreea Petric, Adrian M. Price-Whelan, R. Michael Rich, Alexander H. Riley, Abhijit Saha, Robyn E. Sanderson, Sanjib Sharma, et al. (7 additional authors not shown)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.12302
Pdf link: https://arxiv.org/pdf/2306.12302
Abstract
As our nearest large neighbor, the Andromeda Galaxy provides a unique laboratory for investigating galaxy formation and the distribution and substructure properties of dark matter in a Milky Way-like galaxy. Here, we propose an initial 2-epoch ($\Delta t\approx 5$yr), 2-band Roman survey of the entire halo of Andromeda, covering 500 square degrees, which will detect nearly every red giant star in the halo (10$\sigma$ detection in F146, F062 of 26.5, 26.1AB mag respectively) and yield proper motions to $\sim$25 microarcsec/year (i.e., $\sim$90 km/s) for all stars brighter than F146 $\approx 23.6$ AB mag (i.e., reaching the red clump stars in the Andromeda halo). This survey will yield (through averaging) high-fidelity proper motions for all satellites and compact substructures in the Andromeda halo and will enable statistical searches for clusters in chemo-dynamical space. Adding a third epoch during the extended mission will improve these proper motions by $\sim t^{-1.5}$, to $\approx 11$ km/s, but this requires obtaining the first epoch in Year 1 of Roman operations. In combination with ongoing and imminent spectroscopic campaigns with ground-based telescopes, this Roman survey has the potential to yield full 3-d space motions of $>$100,000 stars in the Andromeda halo, including (by combining individual measurements) robust space motions of its entire globular cluster and most of its dwarf galaxy satellite populations. It will also identify high-velocity stars in Andromeda, providing unique information on the processes that create this population. These data offer a unique opportunity to study the immigration history, halo formation, and underlying dark matter scaffolding of a galaxy other than our own.

The OH Megamaser Emission in Arp,220: the rest of the story

Authors: W. A. Baan, J.N.H.S. Aditya, T. An, H-R. Klöckner
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.12353
Pdf link: https://arxiv.org/pdf/2306.12353
Abstract
The OH Megamaser emission in the merging galaxy Arp220 has been re-observed with the Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). Imaging results of the OH line emission at the two nuclei are found to be consistent with earlier observations and confirm additional extended emission structures surrounding the nuclei. Detailed information about the distributed emission components around the two nuclei has been obtained using a concatenated MERLIN and EVN database with intermediate (40 mas) spatial resolution. Continuum imaging shows a relatively compact West nucleus and a more extended East nucleus in addition to an extended continuum ridge stretching below and beyond the two nuclei. Spectral line imaging show extended emission regions at both nuclei together with compact components and additional weaker components north and south of the West nucleus. Spectral line analysis indicates that the dominant OH line emission originates in foreground molecular material that is part of a large-scale molecular structure that engulfs the whole nuclear region. Compact OH components are representative of star formation regions within the two nearly edge-on nuclei and define the systemic velocities of East and West as 5425 km/s and 5360 km/s. The foreground material at East and West has a 100 km/s lower velocity at 5314 and 5254 km/s. These emission results confirm a maser amplification scenario where the background continuum and the line emission of the star formation regions are amplified by foreground masering material that is excited by the FIR radiation field originating in the two nuclear regions.

Exploring the Evolution of Massive Clumps in Simulations that Reproduce the Observed Milky Way α-element Abundance Bimodality

Authors: Bethany R. Garver, David L. Nidever, Victor P. Debattista, Leandro Beraldo e Silva, Tigran Khachaturyants
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Arxiv link: https://arxiv.org/abs/2306.12388
Pdf link: https://arxiv.org/pdf/2306.12388
Abstract
The Milky Way stellar disk has both a thin and a thick component. The thin disk is composed mostly of younger stars ($\lesssim$8 Gyr) with a lower abundance of $\alpha$ elements, while the thick disk contains predominantly older stars ($\gtrsim$8--12 Gyr) with a higher $\alpha$ abundance, giving rise to an $\alpha$-bimodality most prominent at intermediate metallicities. A proposed explanation for the bimodality is an episode of clumpy star formation, where high-$\alpha$ stars form in massive clumps that appear in the first few Gyrs of the Milky Way's evolution, while low-$\alpha$ stars form throughout the disk and over a longer time span. To better understand the evolution of clumps, we track them and their constituent stars in two clumpy Milky Way simulations that reproduce the $\alpha$-abundance bimodality, one with 10% and the other with 20% supernova feedback efficiency. We investigate the paths that these clumps take in the chemical space ([O/Fe]--[Fe/H]) as well as their mass, star formation rate (SFR), formation location, lifetime, and merger history. The clumps in the simulation with lower feedback last longer on average, with several lasting hundreds of Myr. Some of the clumps do not reach high-$\alpha$, but the ones that do on average had a higher SFR, longer lifetime, greater mass, and form closer to the galactic center than the ones that do not. Most clumps that reach high-$\alpha$ merge with others and eventually spiral into the galactic center, but shed stars along the way to form most of the thick disk component.

by olozhika (Xing Yuchen).

2023-06-22