The cosmic star formation rate evolution from z = 5 to z = 0 from the VIMOS VLT deep survey

Abstract

Context. The VIMOS VLT Deep Survey (VVDS) was undertaken to map the evolution of galaxies, large scale structures, and active galaxy nuclei from the redshift spectroscopic measurements of ∼105 objects down to an apparent magnitude IAB = 24, in combination with a multi-wavelength acquisition for radio, infrared, optical, ultraviolet, and X-rays data. Aims. We present the evolution of the comoving star formation rate (SFR) density in the redshift range 0 < z < 5 using the first epoch data release of the VVDS, that is 11564 spectra over 2200 arcmin2 in two fields of view, the VVDS-0226-04 and the VVDS-CDFS-0332-27, and the cosmological parameters (ΩM, ΩΛ, h) = (0.3, 0.7,0.7). Methods. We study the multi-wavelength non dust-corrected luminosity densities at 0 < z < 2 from the rest-frame far ultraviolet to the optical passbands, and the rest-frame 1500 Åluminosity functions and densities at 2.7 < z < 5. Results. They evolve from z = 1.2 to z = 0.05 according to (1 + z)x with x = 2.05, 1.94, 1.92, 1.14, 0.73, 0.42, and 0.30 in the FUV-1500, NUV-2800, U-3600, B-4400, V-5500, R-6500, and I-7900 passbands, respectively. From z = 1.2 to z = 0.2 the B-band density for the irregularlike galaxies decreases markedly by a factor 3.5 while it increases by a factor 1.7 for the elliptical-like galaxies. We identify several SFR periods; from z = 5 to 3.4 the FUV-band density increases by at most 0.5 dex, from z = 3.4 to 1.2 it decreases by 0.08 dex, from z = 1.2 to z = 0.05 it declines steadily by 0.6 dex. For the most luminous MAB(1500 Å) < -21 galaxies the FUV-band density drops by 2 dex from z = 3.9 to z = 1.2, and for the intermediate -21 < M AB(1500 Å) < -20 galaxies it drops by 2 dex from z = 0.2 to z = 0. Comparing with dust corrected surveys, at 0.4 ≲ z ≲ 2 the FUV seems obscured by a constant factor of ∼ 1.8-2 mag, while at z < 0.5 it seems progressively less obscured by up to ∼0.9-l mag when the dust-deficient early-type population is increasingly dominating the 5-band density. Conclusions. The VVDS results agree with a downsizing picture where the most luminous sources cease to efficiently produce new stars 12 Gyrs ago (at z ≃4), while intermediate luminosity sources keep producing stars until 2.5 Gyrs ago (at z ≃ 0.2). A modest contribution of dry mergers and morphologies evolving towards early-type galaxies might contribute to increase the number density of the bright early types at z < 1.5. Our observed SFR density is not in agreement with a continuous smooth decrease since z ∼ 4. © ESO 2007.