Early results from GLASS-JWST. XI: Stellar masses and mass-to-light ratio of z>7 galaxies

Understand

We exploit James Webb Space Telescope (JWST) NIRCam observations from the GLASS-JWST-Early Release Science program to investigate galaxy stellar masses at z>7.

• We first show that JWST observations reduce the uncertainties on the stellar mass by a factor of at least 5-10, when compared with the highest quality data sets available to date.
• We then study the UV mass-to-light ratio, finding that galaxies exhibit a two orders of magnitude range of M/L_UV values for a given luminosity, indicative of a broad variety of physical conditions and star formation histories.
• As a consequence, previous estimates of the cosmic star stellar mass density - based on an average correlation between UV luminosity and stellar mass - can be biased by as much as a factor of ~6.