meeting 2025 09 08 n57 - JacobPilawa/TriaxSchwarzschild_wiki_6 GitHub Wiki

Finalizing remaining environment questions and cleaning up the past few bullets.

Important notes/details about the environment calculations below:

• I wasn't able to find Abell1836 BCG in the HDC or LDC catalogs, nor the 2MRS++ survey so that is currently left off from this. If we want to add this, I can try to track down a larger spectroscopic survey and attempt the same calculation as I did for H15, but I'm not sure it's that important.
• Mrk1216 and NGC 6086 do not appear to be in Crook+07's HDC or LDC, so I don't have member numbers or halo estimates for those galaxies. They do appear in 2MRS++ though, so I was able to compute nu10 for these galaxies.
• I haven't gotten around to tracking down the sigma/Rb/Rsoi for these galaxies, but I do have that on the to-do list.

Other random notes/things to double check on Jacob's end:

• Ensure that the distances I'm using here are consistent with the distances assumed in the nu10 calculation. There may be slight differences depending on when I updated the distances/switched to group distances. I think they're the same right now but I need to double check.

To determine the number of group members:

• Started by retrieving the data from both the HDC and LDC for the galaxies that I could find.
• For each galaxy in each group, take the K mag reported in Crook+07 and convert to absolute K-band with Mk = k - 5*log10(D) - 25, where D is the "best" measurement I can find (will elaborate below).
• After getting the absolute K-bands, I find only those with Mk<=-23.0. This is the final number I report:
• Note that N57 and N4751 only have entries in the LDC; H15/A1836BCG/N6086/MRK1216 are not in the Crook catalog, so these entries are missing.

Note that N3706 is in this table but isn't actually included; Remco+16 reported the mass incorrectly, so while it initially made my mass cut, it's actually below 3 billion solar masses and gets dropped.

Things to decide:

• Do we want to mix LDC and HDC here? Maybe report LDC alone since that exists for everything except for N57? My primary concern is for N4751.
• Do we just want to leave off the galaxies which aren't in either HDC or LDC and put a note in the text?

In general, the halo masses are taken from the Crook catalogs (specifically the logMp projected mass estimate parameter in their catalogs). There are a number of galaxies for which we take "better" measurements of the halo, either from MASSIVE/other paper (for H15)/for N57 we do our own M200 calculation.

Things to decide:

• What to do about Mrk1216/A6086/A1836? On one hand I can try to compute a similar number like I did for H15; on the other hand it definitely opens up a large can of words and need of description in the text for not much additional information, I think.

I also wanted to briefly summarize the nu10 calculation here, as well as any important caveats or notes:

• Throughout this, I'm setting nubar = 2.8e8, taken from the MASSIVE environment paper.

Nu10 Calculation:

• I start a list of our target galaxies and their accompanying HDC or LDC groups.
• For the majority of our target galaxies, there are >= 10 members in the HDC or LDC groups, which means I do not have to search through 2MRS++ for additional neighbors. In this case, I prioritize neighbors in the HDC over the LDC, and only go into the LDC if I need to.
• Once I have 10 neighbors for a galaxy from the HDC/LDC, I flatten the galaxies in the groups to the same distance (our "best" distance for the different galaxies).
  • There are some galaxies which don't have 10 identified group members across the HDC/LDC, and in these cases, I need to find additional neighbors from the HDC/LDC catalogs. To do this, I search the 2MRS++ for additional galaxies near our target until we reach 10 neighbors which make the magntiude cut. I also "flatten" the distance of these additional neighbors to the group distance, with the caveat that I am preserving the absolute separation. For example, NGC57's SBF distance is 66.9; the Crook+07 distance is 74.47 MPC. N57 has a few neighbors in its LDC, but it's next neighbor from 2MRS++ is listed at 77.38 MPC, meaning there is a 2.91 Mpc separation. When I flatten N57's group to the "correct" 66.9 Mpc distance, I preserve this separation 2.91 Mpc and place the next galaxy at 69.81.
• After I have the updated set of 10 neighbors with the K-band magnitudes, I re-compute the 3d separations with the updated distances, and compute absolute K-band magnitudes using their apparent K band magnitudes and the updated distances. I then convert from magnitude to luminosity assuming solar mag of 3.29.
• The last step is to sum the luminosities out to the 10th neighbor (excluding the target galaxy), and divide by the enclosed volume out to that neighor. This gives nu10, which we divide by 2.8e8 to get the normalized scale.

We wanted to start somewhat formally collecting supermassive black hole mass measurements. I basically have been doing ADS searches for "dynamical black hole mass measurements" or some variation of that search, and have assumed that the Remco+16 "Unification..." paper is complete, and filling in the black hole measurements since then.

Notes about my search:

• Likely missed some of the reverberation/non-stellar/non-CO based dynamical mass measurements just from the nature of my search. There are definitely a few papers I have found, but I paid most attention to stellar or gas based measurements.

Useful larger references:

• Remco+16 "Unification..." paper
• Davis+17 compilation of 44 spiral galaxy Mbh's: paper
• Zhang+19 compilation of Mbh/spin measurements via X-ray reflection spectroscopy: paper
• Sahu+19: compilation of 84 early-type galaxies (42 of which are "new"): paper
• Baldassare+20: Eight new low mass points on M-sigma with virial masses: paper
• Mejia-Restrepo+22: 689 broad line region Mbh estimates: paper
• Sahu+22: Appears to be a follow up/set of updates to the Sahu+19 paper. This source contains ~104 objects: paper
• Winkel+25: Compilationof CARAMEL/GRAVITY/cRM masses for AGN: paper
• Farrah+23b: Compilation of low redshift ETG MBHs: paper
  • Slight addition to this work here: paper

• N3706 is Remco's paper is 1 dex too large. Should be log10(Mbh)~8.77 instead of 9.77; likely just a typo.
• N997's mass is quoted in a strange way, and is thus incorrect in the Big Galaxies + Big Black Holes paper; two galaxies are reported in the original work, one reported in units of 1e8 solar masses; the other reported in log10(Mbh) units, leading to this incorrect Mbh measurement.