The Sloan Digital Sky Survey u-band Galaxy Survey: luminosity functions and evolution

We construct and analyse a u-band selected galaxy sample from the Sloan Digital Sky Survey (SDSS) Southern Survey, which covers 275 deg^2. The sample includes 43223 galaxies with spectroscopic redshifts in the range 0.005 < z < 0.3 and with 14.5 < u < 20.5. The signal-to-noise (S/N) ratio in the u-band Petrosian aperture is improved by co-adding multiple epochs of imaging data and by including sky-subtraction corrections. Luminosity functions for the near-UV 0.1u band (λ≈ 322 ± 26 nm) are determined in redshift slices of width 0.02, which show a highly significant evolution in M* of −0.8 ± 0.1 mag between z= 0 and 0.3; with M*−5 log h₇₀=−18.84 ± 0.05 (AB mag), log φ*=−2.06 ± 0.03 (h³₇₀ Mpc⁻³) and log ρ_L= 19.11 ± 0.02 (h₇₀ WHz⁻¹ Mpc⁻³) at z= 0.1. The faint-end slope determined for z < 0.06 is given by =−1.05 ± 0.08. This is in agreement with recent determinations from the Galaxy Evolution Explorer at shorter wavelengths. Comparing our z < 0.3 luminosity density measurements with 0.2 < z < 1.2 from Classifying Objects by Medium Band Observations in 17 Filters (COMBO-17), we find that the 280-nm density evolves as ρ_L^∝ (1 +z)^β with β= 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.