TheB‐Band Luminosity Function of Red and Blue Galaxies up toz= 3.5

We have explored the redshift evolution of the luminosity function of red andblue galaxies up to $z=3.5$. This was possible joining a deep I band compositegalaxy sample, which includes the spectroscopic K20 sample and the HDFssamples, with the deep $H_{AB}=26$ and $K_{AB}=25$ samples derived from thedeep NIR images of the Hubble Deep Fields North and South, respectively. About30% of the sample has spectroscopic redshifts and the remaining fractionwell-calibrated photometric redshifts. This allowed to select and measuregalaxies in the rest-frame blue magnitude up to $z\sim 3$ and to derive theredshift evolution of the B-band luminosity function of galaxies separated bytheir rest-frame $U-V$ color or specific (i.e. per unit mass) star-formationrate. The class separation was derived from passive evolutionary tracks or fromtheir observed bimodal distributions. Both distributions appear bimodal atleast up to $z\sim 2$ and the locus of red/early galaxies is clearly identifiedup to these high redshifts. Both luminosity and density evolutions are neededto describe the cosmological behaviour of the red/early and blue/latepopulations. The density evolution is greater for the early population with adecrease by one order of magnitude at $z\sim 2-3$ with respect to the value at$z\sim 0.4$. The luminosity densities of the early and late type galaxies with$M_B<-20.6$ appear to have a bifurcation at $z>1$. Indeed while star-forminggalaxies slightly increase or keep constant their luminosity density, "early"galaxies decrease in their luminosity density by a factor $\sim 5-6$ from$z\sim 0.4$ to $z\sim 2.5-3$. A comparison with one of the latest versions ofthe hierarchical CDM models shows a broad agreement with the observed numberand luminosity density evolutions of both populations.Comment: 41 pages, 14 figures, accepted for publication in Ap