Inferring the star-formation histories of massive quiescent galaxies with BAGPIPES: Evidence for multiple quenching mechanisms

Understand

We present Bayesian Analysis of Galaxies for Physical Inference and Parameter EStimation, or BAGPIPES, a new Python tool which can be used to rapidly generate complex model galaxy spectra and to fit these to arbitrary combinations of spectroscopic and photometric data using the MultiNest nested sampling algorithm.

• We extensively test our ability to recover realistic star-formation histories (SFHs) by fitting mock observations of quiescent galaxies from the MUFASA simulation.
• We then perform a detailed analysis of the SFHs of a sample of 9289 quiescent galaxies from UltraVISTA with stellar masses, $M_* > 10^{10}\ \mathrm{M_\odot}$ and redshifts $0.25 < z < 3.75$.
• The majority of our sample exhibit SFHs which rise gradually then quench relatively rapidly, over $1{-}2$ Gyr.