2002/08/31 by C. Wolf, K. Meisenheimer, H. -W. Rix +3 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021513
published as Astron.Astrophys. 401 (2003) 73-98 · 35 pages, 32 figures, submitted to Astronomy & Astrophysics
arxiv created 2002/10/17 · arxiv updated 2009/12/01
We present a detailed empirical assessment of how the galaxy luminosity function and stellar luminosity density evolves over the last half of the universe's age (0.2<z<1.2) for galaxies of different spectral energy distributions (SED). The results are based on ~25,000 galaxies (R<24) with redshift measurements (sigmaz~0.03) and SEDs across 350..930 nm, derived from medium-band photometry in 17 filters, observed as part of the COMBO-17 survey (``Classifying Objects by Medium-Band Observations in 17 Filters'') over three disjoint fields with a total area of 0.78 square degrees. Luminosity functions (LF), binned in redshift and SED-type, are presented in the restframe passbands of the SDSS r-band, the Johnson B-band and a synthetic UV continuum band at 280 nm. We find that the luminosity function depends strongly on SED-type at all redshifts covered. The shape of the LF, i.e. the faint-end power-law slope, does depend on SED type, but not on redshift. However, the redshift evolution of the characteristic luminosity M* and density phi* depends strongly on SED-type: (1) Early-type galaxies, defined as redder than a present-day reference Sa spectrum, become drastically more abundant towards low redshift, by a factor of 10 in the number density phi* from z=1.1 to now, and by a factor of 4 in their contribution to the co-moving r-band luminosity density, jr. (2) Galaxies resembling present-day Sa- to Sbc-colours show a co-moving number density and contribution to jr that does not vary much with redshift. (3) Galaxies with blue spectra reflecting strong star formation decrease towards low redshift both in luminosity and density, and by a factor of 4 in their jr contribution. (abridged)