Constraints on the Evolution of the Galaxy Stellar Mass Function. II. The Quenching Timescale of Galaxies and Its Implication for Their Star Formation Rates

Abstract

Abstract We study the connection between the observed star formation rate–stellar mass (SFR–M *) relation and the evolution of the stellar mass function (SMF) by means of a subhalo abundance matching technique coupled to merger trees extracted from an N-body simulation. Our approach consists of forcing the model to match the observed SMF at redshift , and letting it evolve down to according to a τ model, an exponentially declining functional form that describes the star formation rate decay of both satellite and central galaxies. In this study, we use three different sets of SMFs: ZFOURGE data from Tomczak et al., UltraVISTA data from Ilbert et al., and COSMOS data from Davidzon et al. We also build a mock survey combining UltraVISTA with ZFOURGE. Our modeling of quenching timescales is consistent with the evolution of the SMF down to , with different accuracy depending on the particular survey used for calibration. We tested our model against the observed SMFs at low redshift, and it predicts residuals (observation versus model) within observed scatter along most of the stellar mass range investigated, and with mean residuals below 0.1 dex in the range . We then compare the SFR–M * relation predicted by the model with the observed one at different redshifts. The predicted SFR–M * relation underpredicts the median SFR at fixed stellar mass relative to observations at all redshifts. Nevertheless, the shapes are consistent with the observed relations up to intermediate-mass galaxies, followed by a rapid decline for massive galaxies.