Supplementary, angular momentum

Hamidreza Mahani
  • 1
  • 14 Feb '22

Dear all,

I have a question regarding angular momentum in Illustris, angular_momentum.hdf5 file.

I did not find instructions on linking this file to the group catalog. Would you please let me know how I should use it? For example, if I want to study subhalos without dark matter, this is my code:

subhalo_fields =['SubhaloMass','SubhaloMassType',]
subhalos = gc.loadSubhalos(basePath,135, fields=subhalo_fields)

SubHalo_mass = subhalos['SubhaloMassType']*(10**10)/0.704
S_dm_mass = SubHalo_mass[:,1]
S_stellar_mass = SubHalo_mass[:,4]

DMF= np.where((S_stellar_mass>0)&(S_dm_mass==0.0))[0]

How can I access the angular momentum and kinetic energy of those subhalos? Are the variables GroupEkin{SO} and GroupJstars{SO}?

Thank you very much.

Dylan Nelson
  • 14 Feb '22

Dear Hamid,

The angular_momentum catalog is "complete", meaning that all the datasets in that file have one entry per group (or subhalo). That is, the datasets have the same size as the actual datasets in the group catalog, such as SubhaloMass.

Therefore you can load and use them directly, just don't mix between the groups and subhalos, e.g.

with h5py.File('angular_momentum.hdf5','r') as f:
    SubhaloEkin = f['SubhaloEkin'][()]
    Subhalo_Jstars = f['Subhalo_Jstars'][()]

assert SubhaloEkin.size == S_stellar_mass.size
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