galaxy_merger.py ask

[mahengrui1]

Describe the bug
Hello I'm in a project and your galaxy_merger.py is my main code to simulate the collision of Milkyway and Andromeda. I'm new to AMUSE. I think your code can't change the value, otherwise the galaxy will break by expansion.

To Reproduce
Here is my group's achievement about galaxy_merger.py:

1 fix the wrong default value about function plot gas, the v, from about 10 to 1e25. So the plot is visible.
line29
pynbody_column_density_plot(temp.gas_particles, width=300|units.kpc, units = 'm_p cm^-2', vmin=1e12, vmax=1e25)

2 create an one galaxy model but nothing changes about principles. still expansion

Here is un achivement, maybe a bug, maybe I can't handle it:

1 use galaxy.rotate properly

2 control the diameter of galaxy

3 input mass without breaking plot

For example, if I change total mass:

line46, converter = nbody_system.nbody_to_si(1.0e11|units.MSun, 1.|units.kpc)

then an ultimate expansion is expected. No way to avoid it. I want to input real data of Milkyway and Andromeda but no way.
Expected behavior
real data running Milkyway and Andromeda but no way

Environment (please complete the following information):

• Fedora 17.
• the version of your code is Oct. 2017
  

[ipelupessy]

my apologies, I did not see this earlier! Please consider reporting this at the https://github.com/amusecode/amuse (the main development repository), more people will notice and comment..

[ipelupessy]

its difficult to say what goes wrong - it may be the plotting - if I use the plots w/o pynbody, I get as the final state for the disk particles:

what are the red dots in your plot?