I am studying the dynamics of interacting galactic pairs. I am hoping to run a simulation which treats the galaxies as isolated particles from z = 3 until the present day. My goal is to use the Illustris-3 simulation as the source of my initial conditions, could anyone advise on the most efficient way to extract the mass, velocity and position of such pairs from the database using Python please?

Dylan Nelson

2 Feb '18

Hi James,

Best if you can define a sample of what you would like the z=0 descendants to look like (i.e. stellar mass range).

Then, you can look over all of the central galaxies at z=0 which satisfy this, and examine their SubLink merger trees, to see if they had a merger at z=3 (plus/minus some tolerance).

Perhaps see the very bottom of this thread for an idea. I.e., try to use the `simple.json' return, which gives you back a list of mergers that subhalo experienced. If one happens at a snapshot you are interested in, you can go get more information about it at that point in time, or just prior, e.g. mass, velocity, position.

I am studying the dynamics of interacting galactic pairs. I am hoping to run a simulation which treats the galaxies as isolated particles from z = 3 until the present day. My goal is to use the Illustris-3 simulation as the source of my initial conditions, could anyone advise on the most efficient way to extract the mass, velocity and position of such pairs from the database using Python please?

Hi James,

Best if you can define a sample of what you would like the z=0 descendants to look like (i.e. stellar mass range).

Then, you can look over all of the central galaxies at z=0 which satisfy this, and examine their SubLink merger trees, to see if they had a merger at z=3 (plus/minus some tolerance).

Perhaps see the very bottom of this thread for an idea. I.e., try to use the `simple.json' return, which gives you back a list of mergers that subhalo experienced. If one happens at a snapshot you are interested in, you can go get more information about it at that point in time, or just prior, e.g. mass, velocity, position.

Brilliant - thanks for your help Dylan!