meeting 2025 09 23 gw - JacobPilawa/TriaxSchwarzschild_wiki_6 GitHub Wiki

Context

  • I've started digging into some of the catalog data and have some diagnostics!

  • I started by reading these two papers, and downloading the catalogs associated with the 2022 paper (nearly ~400 GB of data!).

  • Here are some stats I computed from the raw data, which match Table 2 from the Zou+22 paper

Catalog Name Number of Galaxies Number of Galaxies with Spec Z
HSCPDR3 133,554,787 620,627
DESDR2 292,636,425 469,460
DESIDR9 320,060,206 2,712,683
TOTAL 746,251,418 3,802,770

Diagnostics

  • With the data in hand, I've created a number of diagnostics following the suggestions from Chung-Pei's email:

Photo-z vs. spec-z Diagnostics

  • First, here's a plot comparing the specz and photoz's reported in each catalog:
specz vs. photoz
images/250923/spec_z_photo_z.png
  • And I've also recreated their Figure 2, which I'll put next to my version (note that my y-axis reads "Counts" but I've actually normalized my histogram to integrate to 1 as does Zou):
Zou+22 Figure 2 My Figure 2
[images/250923/zou_figure2.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/spec_z_distribution_figure_2.png)

Stellar Mass Diagnostics

  • I've created a bunch of diagnostics related to the stellar masses reported in the catalogs. As a first pass, here are two plots showing the stellar mass distribution across all galaxies (between 1e7 and 1e12 Msun). On the left, I'm plotting only the galaxies which have a specz measurement; on the right, I'm plotting all of the galaxies.
    • For galaxies that have both a specz and a photoz measurement, I take the specz to be the "truth." When there is no specz measurement, I use the photoz that's reported.
Galaxies with Spec Z All Galaxies
[images/250923/mstar_with_zspec_distributions.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/full_mstar_distributions.png)

Breaking into redshift bins for specz galaxies only

  • I've taken the histograms above and broken them into both redshift bins AND splitting by catalog. Note that for this first set of plots, I'm selecting only galaxies which have a specz measurement.
    • The left set of plots (labelled "Mstar in spec-z bins for the three catalogs") is showing the Mstar distributions for galaxies with specz measurements, broken down into both redshift bins and broken down by catalog. Note that the left and right columns are showing the same data, but have different y-axis scales (linear vs log).
    • The right set of plots (labelled "Mstar in spec-z bins for ALL catalogs") combines the three catalogs together to make one "master" set of plots. Again, this is only showing galaxies which have specz measurements.
Mstar in spec-z bins for the three catalogs Mstar in spec-z bins for ALL catalogs
[images/250923/mstar_distributions_3x2.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/mstar_allcatalogs_linear_vs_log.png)

Breaking into redshift bins for ALL galaxies

  • I also created a set of plots using ALL galaxies, but we have to make a choice about which redshift to use in that case (photo-z vs. spec-z). In this plot below, I'm taking the specz if it exists, otherwise I take the photoz measurement.
Mstar for ALL galaixes for the three catalogs Mstar bins for ALL catalogs
[images/250923/mstar_distributions_all_galaxies.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/mstar_distributions_all_catalogs_1x2.png)

Cumulative Distribution Functions

  • I've also created CDF's of the mass function in different redshift bins.
    • The top row of plots shows the CDF for galaxies which have specz measurements only. Again, the left set of plots shows this broken down by catalog, and the right set of plots is showing all three catalogs together.
    • The bottom row of plots shows the same but using ALL galaxies. In this case, I'm taking the specz if it exists; otherwise I take the photoz.
All Catalogs Broken out by catalog
only specz [images/250923/cumulative_all_catalogs_with_specz.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/mstar_cumulative_3x1.png)
all redshifts (specz > photoz) [images/250923/cumulative_all_catalogs_with_allz_hist.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_6/wiki/[[images/250923/mstar_cumulative_3x1_allz_hist.png)

Value Added Catalog Cross Matching

  • The value added catalog from Siduek+24 contains 1337250 additional galaxies, and currently trying to match the full DESI DR9 with this value-added catalog. I've done some preliminary matching of the two catalogs, and at least for the targets I'm reasonably confident for so far, there appears to be quite decent agreement between the DESI reported logMstar and the value added logMstar. Working to quantify this now, but here's a comparison of the two:
    • Note that there are a few issues coming up in the matching of targets, so this shows only galaxies which have a much within 0.1 arcsec between the two catalogs (about 70% of targets)
Value Added Comparison
images/250923/value_added_versus_desi_stellar_masses.png