Match fof halos between baryonic and gravity-only runs TNG300

Sebastian Bocquet
  • 20 Feb '20

I'd need the hydro counterparts for the fof halos in the Dark runs. I'm aware of the subhalo_matching_to_dark.hdf5 files but these seem to be for the subhalo catalogs. Should I cross-match fof and subhalo catalogs first? Alternatively, can I also cross-match by position (i.e., the question is whether the IC are identical between the baryonic and Dark runs?)

Dylan Nelson
  • 20 Feb '20

Hello Sebastian,

The ICs are indeed identical (more importantly, the IDs of the dark matter particles are identical). So yes you can either cross-match by position (I would restrict to a delta_mass tolerance e.g. < 0.3 dex) and/or by ID.

The catalog you mention is by ID, which in general will be more robust, and also work for satellites.

I would suggest you use it, by simply taking the answer for the central subhalo of each FoF. (To cross-match from the FoF catalog to the subhalo catalog, you need only use GroupFirstSub).

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