Early Results from GLASS-JWST. XI. Stellar Masses and Mass-to-light Ratio of <i>z</i> &gt; 7 Galaxies

Santini, P.; Fontana, A.; Castellano, M.; Leethochawalit, N.; Trenti, M.; Treu, T.; Belfiori, D.; Birrer, S.; Bonchi, A.; Merlin, E.; Mason, C.; Morishita, T.; Nonino, M.; Paris, D.; Polenta, G.; Rosati, P.; Yang, L.; Boyett, K.; Bradac, M.; Calabro, A.; Dressler, A.; Glazebrook, K.; Marchesini, D.; Mascia, S.; Nanayakkara, T.; Pentericci, L.; Roberts-Borsani, G.; Scarlata, C.; Vulcani, B.; Wang, Xin
2023
ASTROPHYSICAL JOURNAL LETTERS
DOI
10.3847/2041-8213/ac9586
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 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 stellar-mass density-based on an average correlation between UV luminosity and stellar mass-can be biased by as much as a factor of similar to 6. Our first exploration demonstrates that JWST represents a new era in our understanding of stellar masses at z > 7 and, therefore, of the growth of galaxies prior to cosmic reionization.