Cosmic evolution of the galaxy mass and luminosity functions by morphological type from multi-wavelength data in the CDF-South

Abstract

We constrain the evolution of the galaxy mass and luminosity functions from the analysis of (public) multi-wavelength data in the Chandra Deep Field South (CDFS) area, obtained from the GOODS and other projects, and including very deep high-resolution imaging by HST/ACS. Our reference catalogue of faint high-redshift galaxies, which we have thoroughly tested for completeness and reliability, comes from a deep (S(3.6micron)>1 microJy) image by IRAC on the Spitzer Observatory. These imaging data in the field are complemented with extensive optical spectroscopy by the ESO VLT/FORS2 and VIMOS spectrographs, while deep K-band VLT/ISAAC imaging is also used to derive further complementary statistical constraints and to assist the source identification and SED analysis. We have selected a highly reliable IRAC 3.6micron sub-sample of 1478 galaxies with S(3.6)>10microJy, 47% of which have spectroscopic redshift, while for the remaining objects both COMBO-17 and Hyperz are used to estimate the photometric redshift. This very extensive dataset is exploited to assess evolutionary effects in the galaxy luminosity and stellar mass functions, while luminosity/density evolution is further constrained with the number counts and redshift distributions. The deep ACS imaging allows us to differentiate these evolutionary paths by morphological type, which our simulations show to be reliable at least up to z=1.5 for the two main early- (E/S0) and late-type (Sp/Irr) classes. These data, as well as our direct estimate of the stellar mass function above M=10^(10)M_sun for the spheroidal subclass, consistently evidence a progressive dearth of such objects to occur starting at z=0.7, paralleled by an increase in luminosity. (abridged)