Stellar Populations and Formation Histories of Massive Galaxies Derived from Deep Hubble Space Telescope Grism Data

Vince Estrada-Carpenter(Texas A&M University)

Oct 26, 2020

Understanding the correlations between mass, morphology, stellar populations, and formation history in galaxies is difficult, primarily due to the uncertainties in galaxy star-formation histories. Star-formation histories are better constrained for higher redshift galaxies, observed closer to their formation and quenching epochs. These properties in high redshift galaxies can be difficult to do from ground-based telescopes, as they are subject to higher backgrounds and a high density of telluric (night-sky) emission lines. The HST/WFC3 grism grant us access to (low-resolution) restframe optical spectrum for galaxies at 1 < z < 2. The age and metallicity features present at these wavelengths, along with the sample sizes provided by grism surveys, allow us to better constrain stellar populations and star-formation histories. In my talk, I will discuss research using a forward modeling technique to fit deep HST grism data from the CLEAR (CANDELS Lyα Emission at Reionization) survey. Work which includes studying the mass - stellar metallicity relationship, where we find that massive quiescent galaxies up to a redshift of ~ 1.8 have ~ solar stellar metallicities. As well as a study on the relationship between morphology and formation redshift (when the galaxy formed ~ 50% of their mass) using “non-parametric” star-formation histories, where we find that quiescent galaxies with the highest stellar-mass surface density, log(Σ1) > 10.25, show a minimum formation redshift.

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