Detection of strong evolution in the population of early-type galaxies

Abstract

The standard picture holds that giant elliptical galaxies formed in a single burst at high redshift. Ageing of their stellar populations subsequently caused them to fade and become redder. The Canada-France Redshift Survey provides a sample of about 125 galaxies with the luminosities and colours of passively evolving early-type galaxies and with 0.1 <z < 1. This sample is inconsistent with the standard evolutionary picture for elliptical galaxies with better than 99.9 per cent confidence.