Does "SubhaloBHMass" mean SMBH mass?

Suin Matsui
  • 2
  • 20 Sep '23

Thank you for allowing us to use TNG.

I would like to plot the mass of SMBHs in the galaxy's center using your data, but is it OK to use "SubhaloBHMass" in the group catalog?

The "SubhaloBHMass" description says "Sum of the masses of all black holes in this subhalo." Is it the sum of all the BH masses in the subhalo?
What should I use when I want only the mass of the SMBH in the center?

Dylan Nelson
  • 28 Sep '23

You are right, in general this field is not the best. Rarely would you care about the sum of all SMBH masses in a subhalo. But, thankfully, it is very rare that there is more than 1 SMBH in a subhalo (except for high-mass halos e.g. groups and clusters).

We often compute, by hand, a new quantity "SubhaloMostMassiveBHMass" which is self-explanatory. I would suggest you compute such a quantity, at least for the subhalos you are interested in, and then you can compare with the subhalo catalog quantity, and see if there are any differences.

Suin Matsui
  • 10 Oct '23

Thank you for your clear reply!
The other threads about MBH in this forum also help me to understand.

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