The SDSS u-band Galaxy Survey: Luminosity functions and evolution

Abstract

We construct and analyze a u-band selected galaxy sample from the SDSS Southern Survey, which covers 275 sq. deg. The sample includes 43223 galaxies with spectroscopic redshifts in the range 0.005<z<0.3 and with 14.5<u<20.5. The S/N in the u-band Petrosian aperture is improved by coadding multiple epochs of imaging data and by including sky-subtraction corrections. Luminosity functions for the near-UV ^{0.1}u band (322+-26 nm) are determined in redshift slices of width 0.02, which show a highly significant evolution in M^{star} of -0.8+-0.1 mag between z=0 and 0.3; with M^{star} = -18.84+-0.05 (AB mag), log phi^{star} = -2.06+-0.03 (Mpc^{-3}) and log rho_L = 19.11+-0.02 (W Hz^{-1} Mpc^{-3}) at z=0.1. The faint-end slope determined for z<0.06 is given by alpha=-1.05+-0.08. This is in agreement with recent determinations from GALEX at shorter wavelengths. Comparing our z<0.3 luminosity density measurements with 0.2<z<1.2 from COMBO-17, we find that the 280-nm density evolves as rho_L proportional to (1+z)^{beta} with beta=2.1+-0.2; and find no evidence for any change in slope over this redshift range. By comparing with other measurements of cosmic star formation history, we estimate that the effective dust attenuation at 280 nm has increased by 0.8+-0.3 mag between z=0 and 1.