Dr. Vicente Estrada-Carpenter

Using a forward modeling technique, we fit the stellar populations of a sample of 31 massive quiescent galaxies in the CLEAR survey, in a redshift range of 1 < z < 1.8. Our measurements indicate that massive quiescent galaxies in this redshift range have ~ solar stellar metallicities. Thus, there is no evolution in the stellar metallicity - mass relation, up to a redshift of z ~ 1.8. We also show that many of these galaxies had formed ~70% of their stellar mass by z ~ 2-3.

Combining photometric, G102 grism, and G141 grism data, we constrain the stellar populations and derive "non-parametric" star-formation histories for a sample of 97 massive quiescent galaxies in the CLEAR survey, in a redshift range of 0.8 < z < 2.5. By comparing formation redshifts (where the galaxy formed half its mass) to stellar surface mass densities within 1 kiloparsec we see that the most compact galaxies are biased to form early (z>2.5), while less compact galaxies show a wide range of formation redshifts. Our results favor a scenario where compact galaxies formed rapidly at high redshift, then go through subsequent evolution through minor mergers.