Evolution of galaxy size–stellar mass relation from the Kilo-Degree Survey

Abstract

We have obtained structural parameters of about 340,000 galaxies from the\nKilo Degree Survey (KiDS) in 153 square degrees of data release 1, 2 and 3. We\nhave performed a seeing convolved 2D single S\\'ersic fit to the galaxy images\nin the 4 photometric bands (u, g, r, i) observed by KiDS, by selecting high\nsignal-to-noise ratio (S/N > 50) systems in every bands.\n We have classified galaxies as spheroids and disc-dominated by combining\ntheir spectral energy distribution properties and their S\\'ersic index. Using\nphotometric redshifts derived from a machine learning technique, we have\ndetermined the evolution of the effective radius, \\Re\\ and stellar mass, \\mst,\nversus redshift, for both mass complete samples of spheroids and disc-dominated\ngalaxies up to z ~ 0.6.\n Our results show a significant evolution of the structural quantities at\nintermediate redshift for the massive spheroids ($\\mbox{Log}\\ M_*/M_\\odot>11$,\nChabrier IMF), while almost no evolution has found for less massive ones\n($\\mbox{Log}\\ M_*/M_\\odot < 11$). On the other hand, disc dominated systems\nshow a milder evolution in the less massive systems ($\\mbox{Log}\\ M_*/M_\\odot <\n11$) and possibly no evolution of the more massive systems. These trends are\ngenerally consistent with predictions from hydrodynamical simulations and\nindependent datasets out to redshift z ~ 0.6, although in some cases the\nscatter of the data is large to drive final conclusions.\n These results, based on 1/10 of the expected KiDS area, reinforce precedent\nfinding based on smaller statistical samples and show the route toward more\naccurate results, expected with the the next survey releases.\n