Follow subhalos forward in time

Houda Haidar
  • 9 Dec '22

Dear TNG team,

I wish to study the forward in time evolution of subhalos, starting at z=1 (snap=50 in TNG simulations). But I wish to stop the evolution when either:

1) the subhalo is merged with a more massive one
2) its group is merged with a more massive one. Is there a simple way of doing this without looping over the snapnums?

Furthermore, I noticed that some of the trees appear to be broken, apparently because when a subhalo goes deep into a halo, the subhalo finder gets confused and mixes the satellite with the central. Is there any quick way to find such behaviours without looping over snapnums?

Thank you,

Dylan Nelson
  • 11 Dec '22

The information you need is in the tree, i.e. the "full descendant tree" of the z=1 subhalo. You will need to write a script to determine when conditions (1) and (2) occur.

The "subhalo switching" problem you mention is important here, and I would suggest to carefully design your script to identify such cases and handle them appropriately.

I am not entirely sure what you mean by "looping over snapnums", but you will definitely need to consider the full merger trees. These can each be loaded with one load command, so any looping will be instantaneous.

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