Tracking down subhalos

Elisa Tau
  • 13 Dec '20

Hello!

I have studied some specific subhalos at z=0 using IllustrisTNG-100 and I am now trying to track them down to higher redshifts, but I am not completely sure about how to properly do that.
I have tried using their merger trees information following the JupiterLab tutorial, but what I actually want is to know their IDs corresponding to different snapshots in order to be able to study the same propperties at different redshifts, and also study their evolution. How can I do this?
Many thanks in advance!

Kind regards,
Elisa.

Dylan Nelson
  • 15 Dec '20

Hi Elisa,

You should load the MPB from the merger tree, then use the fields SnapNum and SubfindID, which go together as pairs to tell you the progenitor at all previous times.

Elisa Tau
  • 15 Dec '20

Hi Dylan,

Thank you very much for the help!
Do these fields also work to track down halos instead of subhalos? Or should I use the LHaloTree available fields in order to do that?

Dylan Nelson
  • 15 Dec '20

All merger trees, including LHaloTree, work on (Subfind) subhalos, not (FoF) halos.

So if you want to track a halo through time, you should find its central subhalo (GroupFirstSub), then use a merger tree, at each snapshot going from the tracked subhalo back to its parent halo (SubhaloGrNr).

Elisa Tau
  • 15 Dec '20

Oh I see, I will try to do that when it comes to tracking FoF halos then.
Thank you again for the information!

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