Stellar populations of galaxies in the ALHAMBRA survey up to \(z \sim 1\). IV. Properties of quiescent galaxies on the stellar mass-size plane

Abstract

We aim at performing a comprehensive study of the stellar population properties of quiescent galaxies as a function of their sizes, stellar masses and redshifts, to constrain their driver and the most plausible evolutive scenarios that explain their growth in size. After selecting all the quiescent galaxies from the ALHAMBRA survey, we built a shared sample of \(\sim850\) quiescent galaxies with reliable measurements of sizes from HST. This sample is complete in stellar mass and luminosity, \(I\le23\), whose stellar population properties were retrieved using the SED-fitting code MUFFIT with various SSP model sets (BC03 and EMILES). Ages, metallicities, extinctions, SFR, and sSFR are studied on the stellar mass--size plane as function of size through a bidimensional and locally weighted regression method, LOESS, and a Monte Carlo approach to reduce the impact of uncertainties. Our results reveal that there are correlations between the stellar population properties of quiescent galaxies and both their stellar masses and sizes since \(z\sim1\). At fixed stellar mass, the more compact the quiescent galaxy, the older and more rich in metals (up to \(2\)--\(3\) Gyr and \(0.2\) dex, respectively). There are also hints pointing out that more compact galaxies may present slight lower SFR, sSFR, and extinctions respect their more extended counterparts at same stellar mass (up to \(0.5\) dex and \(<0.1\) mag, respectively). We obtain an empirical relation for the driver of the stellar populations expressed as \(M_\star \propto r_\mathrm{c}^\alpha\), where \(\alpha={0.58 \pm 0.07,\ 0.52 \pm 0.07,\ 0.64 \pm 0.09}\) for BC03 and EMILES SSP models, respectively. There are hints to support that velocity dispersion are tightly correlated to the stellar content of galaxies, and therefore, the driver can be partly linked to the dynamical properties of galaxies and to their gravitational potential.