I’m having a hard time finding the spatial resolution for when two black holes merge in IllustrisTNG 50-1. I found an article which says in section 2.2 “A merger is defined when two BHs come within a softening length of 1 kpc” but this is for the Illustris simulation (https://arxiv.org/pdf/2507.11813). My question is, does this apply for the TNG50-1 simulation?
Dylan Nelson
18 Aug
This is roughly correct, but not exactly.
This will be about 2.5x smaller in TNG50-1 than TNG100-1 (or Illustris-1), as this is the ratio of the gravitational softening lengths, given the resolution differences.
In addition, this value is just approximate, not exact. In practice two SMBHs will merge if they enter each others "neighborhoods", that are defined in terms of the radius containing the N nearest gas cells (so this varies in time somewhat).
Hello,
I’m having a hard time finding the spatial resolution for when two black holes merge in IllustrisTNG 50-1. I found an article which says in section 2.2 “A merger is defined when two BHs come within a softening length of 1 kpc” but this is for the Illustris simulation (https://arxiv.org/pdf/2507.11813). My question is, does this apply for the TNG50-1 simulation?
This is roughly correct, but not exactly.
This will be about 2.5x smaller in TNG50-1 than TNG100-1 (or Illustris-1), as this is the ratio of the gravitational softening lengths, given the resolution differences.
In addition, this value is just approximate, not exact. In practice two SMBHs will merge if they enter each others "neighborhoods", that are defined in terms of the radius containing the N nearest gas cells (so this varies in time somewhat).