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

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 I-AB <= 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 (alpha = -1.19 +/- 0.07) compared to the bulge- dominated population (alpha = -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-I)(AB) > 0.9 and bright galaxies showing a strongly decreasing LF slope alpha = +0.55 +/- 0.21, and 32% of blue (B-I) 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 similar or equal to 1, but the volume density of this population is increasing by a factor 2.7 between z similar to 1 and z similar to 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 similar to 1 and z similar to 0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.