Characterizing the satellites of massive galaxies up to z2: young populations to build the outskirts of nearby massive galaxies

Abstract

The accretion of minor satellites is currently proposed as the most likely mechanism to explain the significant size evolution of the massive galaxies during the last 10 Gyr. In this paper, we investigate the rest-frame colours and the average stellar ages of satellites found around massive galaxies (Mstar 1011 M) since z2. We find that the satellites have bluer colours than their central galaxies. When exploring the stellar ages of the galaxies, we find that the satellites have similar ages to the massive galaxies that host them at high redshifts, while at lower redshifts they are, on average, 1.5 Gyr younger. If our satellite galaxies create the envelope of nearby massive galaxies, our results would be compatible with the idea that the outskirts of those galaxies are slightly younger, metal-poorer and with lower [a/Fe] abundance ratios than their inner regions ©2012 The Authors.