meeting 2024 03 25 n57 - JacobPilawa/TriaxSchwarzschild_wiki_5 GitHub Wiki

• Note that O'Sullivan assumes a distance of 72.53, whereas we assume 66.8. I've rescaled O'Sullivan's distance to ours in the plot below.
• At the outermost point of our data, we want a halo with enclosed mass M = 7.45e11 Msun; O'Sullivan wants something like 9.75e11 Msun
• Note that the errors on the plot below are ~20%; I wasn't able to extract the uncertainties from the O'Sullivan paper efficiently.

• I've been working with the black hole mass measurement from 2016: https://ui.adsabs.harvard.edu/abs/2016MNRAS.462.2847M/abstract
• However, there was a 2020 study which claimed a binary with a total mass of 10 billion Msun, in contrast to the ~7 billion Msun black hole before: https://iopscience.iop.org/article/10.3847/1538-4357/accffa

• Note that in today's version, I've removed NGC5516 so the color for NGC7619 is different. Everything else is the same, though.

There are just a few lingering issues that I think I have sorted out, but still need to implement. This essentially leads to:

• I currently am finding one additional neighbor in the HDC for NGC3091 and NGC7619.
• I currently have 7 neighbors out of 130 total which fall below the -23.0 cutoff.

The source of these remaining discrepencies is very subtle, but I think I tracked it down (I still need to verify). The long story short is that:

• HDC/LDC catalogs on their own store the default K-band magnitude from 2MASS along with the group information.
• However, when we compute nu10, we aren't using the default 2MASS K-band magnitude, but rather one of the modified magntiudes present in the full data release of the 2MASS survey. Specifically, we compute Mk from the "k_m_ext" paramter in the 2MASS survey, which should be the "total extinction corrected magnitude."
• In general, the default K-Band magnitude is slightly different than the k_m_ext magnitude, often by ~0.1 mag or so (small but present).
• When counting the number of galaxies in HDC or LDC, I am using the default K mag associated with the neighbors since that is what is present directly in HDC/LDC; the result is that there are two galaxies (N3091 and N7619) which, when using the extinction-corrected magntiude, have one less/one more neighbor than the HDC/LDC would suggest.
• This also impacts a few neighbors which, after updating the distances of the full groups, now give magntiudes fainter than our cutoff of -23.0. This impacts 1 4486 neighbor, 4 4649 neighbors, 1 1550 neighbor, and 1 3091 neighbor.
• Long story short: HDC and LDC reports magnitudes not corrected for extinction; my calculations are using magnitudes which HAVE been extinction corrected.

Despite the remaining, minor changes, the results from last week are remarkably consistent with those from this week.