SQuIGGLE: Studying Quenching in Intermediate-z Galaxies -- Gas, AnguLar Momentum, and Evolution

Abstract

We describe the SQuIGG LE survey of intermediate-redshift post-starburst galaxies. We leverage the large sky coverage of the SDSS to select ∼1300 recently-quenched galaxies at 0.5 < z ≤ 0.9 based on their unique spectral shapes. These bright, intermediate-redshift galaxies are ideal laboratories to study the physics responsible for the rapid quenching of star formation: they are distant enough to be useful analogs for high-redshift quenching galaxies, but low enough redshift that multi-wavelength follow-up observations are feasible with modest telescope investments. We use the Prospector code to infer the stellar population properties and non-parametric star formation histories of all galaxies in the sample. We find that SQuIGG LE galaxies are both very massive (M * ∼ 10 11.25 M ) and quenched, with inferred star formation rates 1M yr −1 , more than an order of magnitude below the star-forming main sequence. The best-fit star formation histories confirm that these galaxies recently quenched a major burst of star formation: > 75% of SQuIGG LE galaxies formed at least a quarter of their total stellar mass in the recent burst, which ended just ∼ 200 Myr before observation. We find that SQuIGG LE galaxies are on average younger and more burst-dominated than most other z 1 poststarburst galaxy samples. This large sample of bright post-starburst galaxies at intermediate redshift opens a wide range of studies into the quenching process. In particular, the full SQuIGG LE survey will investigate the molecular gas reservoirs, morphologies, kinematics, resolved stellar populations, AGN incidence, and infrared properties of this unique sample of galaxies in order to place definitive constraints on the quenching process.