The evolution of the luminosity functions in the FORS deep field from low to high redshift

Abstract

Received -; accepted - Abstract. We present the redshift evolution of the restframe galaxy luminosity function (LF) in the red r', i', and z' bands as derived from the FORS Deep Field (FDF), thus extending the results published in Gabasch et al. (2004a) to longer wavelengths. Using the deep and homogeneous I-band selected dataset of the FDF we are able to follow the red LFs over the redshift range 0.5 < z < 3.5. The results are based on photometric redshifts for 5558 galaxies derived from the photometry in 9 filters achieving an accuracy ofz/(zspec + 1) ≤ 0.03 with only ∼ 1% outliers. A comparison with results from the literature shows the reliability of the derived LFs. Because of the depth of the FDF we can give relatively tight constraints on the faint-end slopeof the LF: The faint-end of the red LFs does not show a large redshift evolution and is compatible within 1� to 2� with a constant slope over the redshift range 0.5 ∼ < z ∼ < 2.0. Moreover, the slopes in r', i', and z' are very similar with a best fitting value of � = −1.33 ± 0.03 for the combined bands. There is a clear trend ofto steepen with increasing wavelength: �UV &u' = −1.07 ± 0.04 → �g'&B = −1.25 ± 0.03 → �r'&i'&z' = −1.33 ± 0.03. We subdivide our galaxy sample into four SED types and determine the contribution of a typical SED type to the overall LF. We show that the wavelength dependence of the LF slope can be explained by the relative contribution of different SED-type LFs to the overall LF, as different SED types dominate the LF in the blue and red bands. Furthermore we also derive and analyze the luminosity density evolution of the different SED types up to z ∼ 2. We investigate the evolution of Mand � � by means of the redshift parametrization M � (z) = M �