The VIMOS-VLT Deep Survey: Galaxy luminosity function per morphological type up to z = 1.2

Abstract

Aims. We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z = 1.2. Methods. We use a sample of 605 spectroscopic redshifts with IAB ≤24 in the Chandra Deep Field South from the VIMOS-VLT Deep Survey, 3555 galaxies with photometric redshifts from the COMBO-17 multi-color data, coupled with multi-color HST/ACS images from the Great Observatories Origin Deep Survey. We split the sample in bulge- and disk-dominated populations on the basis of asymmetry and concentration parameters measured in the rest-frame B-band. Results. We find that at z = 0.4-0.8, the LF slope is significantly steeper for the disk-dominated population (α = -1.19 ±0.07) compared to the bulge-dominated population (α = -0.53 ±0.13). The LF of the bulge-dominated population is composed of two distinct populations separated in rest-frame color: 68% of red (B - 1)AB > 0.9 and bright galaxies showing a strongly decreasing LF slope α = +0.55 ± 0.21, and 32% of blue (B - 1)AB < 0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z - 1, but the volume density of this population is increasing by a factor 2.7 between z - 1 and z - 0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 mag between z - 1 and z - 0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies. © ESO 2006.