finding halo centers, displaying numerical values of subhalos on plots

Daniel McKeown
  • 22 Feb '16

Hello, I am really enjoying my past few days working on illustris. My goal is to plot the evolution of dark matter, stars, gas, and black holes across redshifts and track galaxy evolution. I was wondering if there is a simple way to find the center of the subhalo for dm, gas, and stars, and also, if there is a simple way to display the numerical values associated with these fields on the plot similar to the one shown in the example. This was a very nice script which I have used to make many other histograms by the way. Finally, I will absolutely be sure to cite everything before I publish any work. This is a very fascinating project and I am enjoying it greatly.



Dylan Nelson
  • 29 Feb '16

Hi Daniel,

There is nothing available pre-computed for individual subhalo centers for the different particle types (DM, gas, stars, BHs).

The SubhaloPos field will correspond to the position of a particle of some type, but it could be any, and this is the "most bound" position.

If you want a center for each component separately, you'll have to calculate it from the particle data - the subhalo particles alone should do fine, and a "shrinking sphere" type approach is probably a good start.

Daniel McKeown
  • 24 Mar '16

Hello, I have a plot of the mass densities of gas, dm, stars, and the black hole, (though it's of course a little spike that's hard to see in the scale). I was wondering if you could take a look at my plot and give some feedback. My main question concerns normalizing the plots. Do I need to divide the calculated totalmasses of each type by a particular value for each type? (it looked like something like this was done for the example of calculating solar metallicity with a certain radii. Thanks for all the help, this simulation is fantastic.!

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