Early Results from GLASS-JWST. XI. Stellar Masses and Mass-to-light Ratio of z > 7 Galaxies

January 2023 • 2023ApJ...942L..27S

Authors • 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. • CalabrĂ², A. • Dressler, A. • Glazebrook, K. • Marchesini, D. • Mascia, S. • Nanayakkara, T. • Pentericci, L. • Roberts-Borsani, G. • Scarlata, C. • Vulcani, B. • Wang, Xin

Abstract • 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 ~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.


IPAC Authors


Takahiro Morishita

Assistant Scientist