meeting 2025 10 28 gw - JacobPilawa/TriaxSchwarzschild_wiki_6 GitHub Wiki

Doing some follow-ups from the meeting at the end of last week on a variety of different questions.

Most importantly, I think I managed to figure out a way to easily query the the various WISE data, which should in theory allow us to figure out what W1/W2 Zou (and others) were exactly using in their SED fitting.

A note on the WISE2MBH Sample:

• In the last meeting, we had some discussion on what went into creating the WISE2MBH sample of black hole estimates, and I want to outline that briefly here. The two most relevant papers are the ETHER description paper and WISE2MBH.

In short, the sample of MBHs was determined by:

• First compiling a list of ~3.8 million extragalactic sources from HyperLeda/the Million Quasar Catalog/Veron-Cetty AGN catalog/2M++ redshift survey/ROMA BZCat Blazar catalog/2MRS sample/and the ~1 million galaxies from Chang+15
• Roughly ~1.7 million of those have existing Mbh measurements or estimates
• For the galaxies which do not have an existing measurement, WISE2MBH goes to the AllWISE catalog and cross-matches their soures (with 3'' radius), and they find roughly ~95% of matches in allWISE, leaving roughly ~2 million sources for which they use their algorithm to determine the Mbh mass estimates

Some important things so that I don't forget:

• I don't have full agreement yet, but I think I understand some of the differences between WISE2MBH vs. Zou; I need to be extra careful about which magnitude system they're adopting.
• I also need to be careful about which WISE catalog they use; WISE2MBH appears to use AllWISE (and WXSC when available), whereas Zou appears to use unWISE throughout.
  • unWISE assumes everything is a point source; in particular for the MASSIVE galaxies, this is likely significantly biasing magntiudes for our galaxies since they are so large as noted here.

I've been struggling to reproduce the magnitudes that are listed in Zou+22 (and reported in the DESI DR9 data) from either the UNWISE or the ALLWISE data. For reference, last time we met, I had been computing my own M* from the W1 and W2 channels reported in Zou+22. These (allegedly) came from DESI DR9, which Zou+19/Zou+22 come from unWISE, but there's also some vague statements in these works about using the "ALLWISE" data, so I queried both databases for a comparison of the magntiudes.

DESI DR9:

• The magntiudes here are reported simply as the W1 and W2 magntiudes, so I just simply grab those.

ALLWISE:

• ALLWISE has two columns "w1mpro" and "w2mpro" which are the "instrumental profile-fit photometry magnitude, band 1/2", which I'm assuming to be the final W1 and W2 magntiudes.

unWISE:

• as noted here, the unWISE catalog reports fluxes rather than magnitudes, and says to use 22.5-2.5*log10(flux) to get the magnitudes.
• Note that this catalog models everything as a point source, which is likely not the best approach for our use case.

It's also noteworthy that the Zou+22 paper says that they used SFD+98 for the extinction correction, which isn't necessarily true for the raw WISE data.