CANDELS passive and massive early-type galaxies

We study the evolution of the number density, as a function of the size, of passive early-type galaxies (ETGs) with a wide range of stellar masses (10^10^M_{sun}_<M_*_<~10^11.5^M_{sun}_) from z~3 to z~1, exploiting the unique data set available in the GOODS-South field, including the recently obtained WFC3 images as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). In particular, we select a sample of ~107 massive (M_*_>10^10^M_{sun}_), passive (SSFR<10^-2^/Gyr), and morphologically spheroidal galaxies at 1.2<z<3, taking advantage of the panchromatic data set available for GOODS, including VLT, CFHT, Spitzer, Chandra, and HST ACS+WFC3 data.

We find that at 1<z<3 the passively evolving ETGs are the reddest and most massive objects in the universe, and we prove that a correlation between mass, morphology, color, and star formation activity is already in place at that epoch. We measure a significant evolution in the mass-size relation of passive ETGs from z~3 to z~1, with galaxies growing on average by a factor of two in size in a 3Gyr timescale only. We also witness an increase in the number density of passive ETGs of 50 times over the same time interval.