Pure luminosity evolution models: too few massive galaxies at intermediate and high redshift

Abstract

We compare pure luminosity evolution (PLE) models with recent data at low and high redshift. These models assume that massive galaxies were assembled and formed most of their stars at high redshift (z > 3) and have evolved without merging or substantial dust obscuration since then. Our models span the full range of plausible metallicities, initial mass functions (IMF's) and star formation histories. We require them to reproduce the abundance of galaxies by colour and luminosity in the Sloan Digital Sky Survey and we investigate whether they can simultaneously fit (i) the observed galaxy counts as a function of redshift in magnitude limited surveys with K < 20, and (ii) the colour and M/L ratio evolution of red sequence galaxies in clusters. All models that are consistent with (ii) predict galaxy counts at 1.5 < z < 3 which lie above the observations. Models with an IMF slope similar to the Salpeter value lie far above the data. We conclude that the majority of massive galaxies were either assembled relatively late in this redshift interval or were substantially obscured by dust at these redshifts.