LOGMSTAR values 0.5 dex higher than SDSS MPA-JHU

[dirkscholte]

When comparing the FastSpec stellar mass measurements to SDSS MPA-JHU I noticed a pretty large constant offset between the two measurements. Whether this is due to an issue or just the result of different modelling it might be worth a warning to users out there to keep this in mind when comparing to SDSS results. (Fig below).

This figure is for BGS iron at z< 0.06, however using the mass challenge sample yields similar results. This result is after matching the h values of both catalogs.

For the sample used for the stellar mass challenge I also compared the mass challenge sample to the NSA catalog Sersic stellar masses:

And r-band absolute magnitudes:

As well as the synthesized absolute magnitudes of the ugriz-bands in the FastSpec catalog:

[moustakas]

Pulling in some additional discussion from the Slack/fastspecfit channel:

Here is a comparison of ~13k Fuji sv3-bright galaxies using fastspec (simultaneous fitting of the DESI spectroscopy and photometry) against the GSWLC-2 catalog (https://salims.pages.iu.edu/gswlc). The overall median offset is ~0.28 dex (same H0 and IMF), or ~0.23 dex above ~10^10.5 Msun:

For comparison, here are my fastphot stellar masses, based on just fitting the broadband photometry (but using the DESI redshift, of course). The median offset is +0.19 dex and the scatter is significantly smaller:

[ecylchang]

Hi, I tried to compare the stellar mass with respect to the color (g-r and g-z) for DESI LRGs. I used the stellar mass values obtained from fastspecfit, the UM PCA DR12 sample, and the UVISTA sample. It seems that the trend in stellar mass from fastspecfit differs from that observed in the DR12 and UVISTA samples. Despite the offsets, the stellar mass with respect to g-r/g-z is increasing in the fastspecfit sample, unlike the decrease observed in other samples. All samples are cut with z from 0.6 to 0.7. ![Uploading Screenshot 2023-11-28 at 8.41.15 PM.png…]()

[moustakas]

See discussion in #166.