mclindner / galcollide Goto Github PK

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Combining galaxy models to create an initial condition for a collision:
Run "python GalCollide.py" to produce initial condition of two galaxies in a Keplerian orbit.
Place galaxy models in InitialConditions directory and specify file name in Parameters.py
The output file name is specified along with orbital parameters in Parameters.py

Example Parameters.py file:
########################################
#!/usr/bin/env python

import pynbody

# Paths to tipsy files for galaxy models
Gal1 = pynbody.load('./InitialConditions/initMW')
Gal2 = pynbody.load('./InitialConditions/initMW2')

# dDelta for changa param file
dDelta = .01

# Perigalactic distance in kpc
d_perigalactic = 14.8

# Initial separation distance in kpc
initial_separation = 10**2

# Eccentricity of system
eccentricity = 0.99

# Time in Myr since first perigalacticon passage of desired output snapshot
time = 250

# Dynamical mass of the system in kg
mDyn =  1.312687200755e+42

# Output file name
writename = "TheMice.tipsy"

# Euler angles to transform each galaxy by
Omega1, w1, i1 = 0, 4.10152, 0.261799
Omega2, w2, i2 = 0, 3.49066, 0.436332

# Transform galaxies by Euler angles
transform = True
########################################

Outputs:
writename.tipsy
writename.tipsy.param
writename.tipsy.director
writename.tipsy.info

Copy outputs (writename*) to your ChaNGa working directory and run!

The final tipsy snapshot that is output is at the time since first perigalacticon passage specified in the Parameters.py file.

Once finished, you can place the ChaNGa output files into the data directory and run MakeMovie to create a .gif of the collision, which will be saved in the Animations directory.

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Transforming to observation frame:
Move your changa outputs to the Data directory. To transform a tipsy snapshot 
(writename.tipsy) into the observation frame of reference, specify viewing angles and scaling factors in ObservationParameters.py. 

Example ObservationParameters.py file:
########################################
#!/usr/bin/env python

import pynbody

# Tipsy snapshot to transform into observation frame
snapshot = pynbody.load('./Data/TheMice.tipsy.005000')

# Length scale factor
L = 39.5

# Velocity scale factor
V = 165

# Viewing angle relative to orbital plane
w = 1.36136
i = -0.767945
Omega = -2.26893
########################################

Next, run ObservationFrame.py, which will output the final product, scaled.tipsy.

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Making a movie using ChaNGa outputs:
Copy .ppm files to Data directory, then run MakeMovie.py