Hello: What does the "mass_bhs" field in the …/subhalos/subhalo_id/ endpoint of the API mean? Presumably, it contains the sum of masses of all black holes in this subhalo. But its value differs from that of the "SubhaloBHMass" field in the Subfind subhalo catalogs. For instance, /api/Illustris-3/snapshots/41/subhalos/0/ has mass_bhs = 0.008207 but this subhalo has SubhaloBHMass = 0.00059755036 in the subhalo catalog. Thanks!
There are two black hole masses floating around, the BH_Mass field of PartType5, which the docs describe as "Actual mass of the BH; does not include gas reservoir. Monotonically increases with time according to the accretion prescription, starting from the seed mass." And the Masses field of PartType5 which would be the mass used directly in the simulation (e.g. for gravity).
As you say the SubhaloBHMass field is the sum of these first BH_Mass values for all BHs in the subhalo.
But, the mass_* fields in the API (e.g. when searching, or in the subhalo endpoint) are the entries of SubhaloMassType split out, and so mass_bhs is SubhaloMassType, i.e. the second.
Re-opening this old thread... just to be sure: if I want to extract the profile of the total halo mass then I want to use Masses (and not BH_Mass) is that correct? Thanks!
Yes this would be consistent for e.g. a circular velocity curve.
On the other hand, the BH contribution to the total halo mass profile should be negligible at any appreciable distance.