Evolution of the Galaxy Luminosity Function at z < 0.3

Abstract

We measure the redshift-dependent luminosity function and the comoving radial density of galaxies in the Sloan Digital Sky Survey Data Release 1 (SDSS DR1). Both measurements indicate that the apparent number density of bright galaxies increases by a factor ~3 as redshift increases from z=0 to z=0.3. This result is robust to the assumed cosmology, to the details of the K-correction and to direction on the sky. These observations are most naturally explained by significant evolution in the luminosity and/or number density of galaxies at redshifts z < 0.3. Such evolution is also consistent with the steep number-magnitude counts seen in the APM Galaxy Survey, without the need to invoke a local underdensity in the galaxy distribution distribution or magnitude scale errors.