The ALHAMBRA survey(star) : B-band luminosity function of quiescent and star-forming galaxies at 0.2 <= z < 1 by PDF analysis

Aims. Our goal is to study the evolution of the B-band luminosity function (LF) since z similar to 1 using ALHAMBRA data. Methods. We used the photometric redshift and the I-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I <= 24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift - magnitude - galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also included in our analysis. Results. We modelled the LF with a redshift-dependent Schechter function affected by the same selection effects than the data. The measured ALHAMBRA LF at 0.2 <= z < 1 and the evolving Schechter parameters both for quiescent and star-forming galaxies agree with previous results in the literature. The estimated redshift evolution of M-B(star) alpha Qz is Q(SF) = -1.03 +/- 0.08 and Q(Q) = -0.80 +/- 0.08, and of log(10) phi(star) alpha Pz is P-SF = -0.01 +/- 0.03 and P-Q = -0.41 +/- 0.05. The measured faint-end slopes are alpha(SF) = -1.29 +/- 0.02 and alpha(Q) = -0.53 +/- 0.04. We find a significant population of faint quiescent galaxies with M-B greater than or similar to 18, modelled by a second Schechter function with slope beta = -1.31 +/- 0.11. Conclusions. We present a robust methodology to compute LFs using multi-filter photometric data. The application to ALHAMBRA shows a factor 2.55 +/- 0.14 decrease in the luminosity density j(B) of star-forming galaxies, and a factor 1.25 +/- 0.16 increase in the jB of quiescent ones since z = 1, confirming the continuous build-up of the quiescent population with cosmic time. The contribution of the faint quiescent population to jB increases from 3% at z = 1 to 6% at z = 0. The developed methodology will be applied to future multi-filter surveys such as J-PAS.