Further constraints on the evolution of Ks-selected galaxies in the GOODS/CDFS field

We have selected and analysed the properties of a sample of 2905 K-s < 21.5 galaxies in similar to 131 arcmin(2) of the Great Observatories Origins Deep Survey (GOODS) Chandra Deep Field South (CDFS), to obtain further constraints on the evolution of K-s-selected galaxies with respect to the results already obtained in previous studies. We made use of the public deep multiwavelength imaging from the optical B through the infrared (IR) 4.5-mu m bands, in conjunction with available spectroscopic and COMBO17 data in the CDFS, to construct an optimized redshift catalogue for our galaxy sample. We computed the K-s-band luminosity function and determined that its characteristic magnitude has a substantial brightening kand a decreasing total density from z= 0 to < z >= 2.5. We also analysed the colours and number density evolution of galaxies with different stellar masses. Within our sample, and in contrast to what is observed for less massive systems, the vast majority (similar to 85-90 per cent) of the most massive (M > 2.5 x 10(11) M-circle dot) local galaxies appear to be in place before redshift z similar to 1. Around 65-70 per cent of the total assemble between redshifts z= 1 and 3 and most of them display extremely red colours, suggesting that plausible star formation in these very massive systems should mainly proceed in obscured, short-time-scale bursts. The remaining fraction (up to similar to 20 per cent) could be in place at even higher redshifts z= 3-4, pushing the first epoch of formation of massive galaxies beyond the limits of current near-IR surveys.