Connection between Stellar Mass Distributions within Galaxies and Quenching Since z=2

Abstract

We study the history from z similar to 2 to z similar to 0 of the stellar mass assembly of quiescent and star-forming galaxies in a spatially resolved fashion. For this purpose, we use multi-wavelength imaging data from the Hubble Space Telescope (HST) over the GOODS fields and the Sloan Digital Sky Survey (SDSS) for the local population. We present the radial stellar mass surface density profiles of galaxies with M-* > 10(10) M-circle dot, corrected for mass-to-light ratio (M-*/L) variations, and derive the half-mass-radius (R-m), central stellar mass surface density within 1 kpc (Sigma(1)) and surface density at R-m (Sigma(m)) for star-forming and quiescent galaxies and study their evolution with redshift. At fixed stellar mass, the half-mass sizes of quiescent galaxies increase from z similar to 2 to z similar to 0 by a factor of similar to 3-5, whereas the half-mass sizes of star-forming galaxies increase only slightly, by a factor of similar to 2. The central densities Sigma(1) of quiescent galaxies decline slightly (by a factor of less than or similar to 1.7) from z similar to 2 to z similar to 0, while for star-forming galaxies Sigma(1) increases with time, at fixed mass. We show that the central density Sigma(1) has a tighter correlation with specific star-formation rate (sSFR) than Sigma(m) and for all masses and redshifts galaxies with higher central density are more prone to be quenched. Reaching a high central density (Sigma(1) greater than or similar to 10(10) M-circle dot kpc(2)) seems to be a prerequisite for the cessation of star formation, though a causal link between high Sigma(1) and quenching is difficult to prove and their correlation can have a different origin.