Star formation histories of LEGA-C galaxies

We present individual star formation histories (SFHs) of ~3000 massive galaxies (log(M*/M_{sun}_)>10.5) from the Large Early Galaxy Astrophysics Census spectroscopic survey at a lookback time of ~7 billion yr and quantify the population trends leveraging 20hr deep-integrated spectra of these ~1800 star-forming and ~1200 quiescent galaxies at 0.6<z<1.0. Essentially all galaxies at this epoch contain stars of age <3Gyr, in contrast with older massive galaxies today, facilitating better recovery of previous generations of star formation at cosmic noon and earlier.

We conduct spectrophotometric analysis using parametric and nonparametric Bayesian stellar population synthesis modeling tools-Bagpipes and Prospector-to constrain the median SFHs of this mass complete sample and characterize population trends. A consistent picture arises for the late-time stellar mass growth when quantified as t50 and t90, corresponding to the age of the Universe when galaxies formed 50% and 90% of their total stellar mass, although the two methods disagree at the earliest formation times (e.g., t10).