Astronomy and Astrophysics, volume 334, 99-109 (1998/6-1)
Evolution of the colour-magnitude relation of early-type galaxies in distant clusters.
KODAMA T., ARIMOTO N., BARGER A.J. and ARAGON-SALAMANCA A.
Abstract (from CDS):
We present a thorough quantitative analysis of the evolution of the colour-magnitude relation for early-type galaxies in 17 distant clusters with redshifts 0.31<z<1.27 using the Kodama & Arimoto (1997A&A...320...41K) evolutionary model for elliptical galaxies. The model is calibrated to reproduce the colour-magnitude relation for Coma ellipticals at z∼0 and gives the evolution of the slope and zero-point as a function of redshift. We find no significant differences between the colour-magnitude relations of the clusters in our sample. The slopes can be reproduced by a single model sequence in which all elliptical galaxies are assumed to be equally old (the maximum age difference allowed for the brightest 3 magnitudes is only 1Gyr) and to have mean stellar metallicities which vary as a function of galaxy luminosity. The zero-points of the colour-magnitude relations constrain the epoch of major star formation in early-type galaxies to zf>2-4. This study provides two important constraints for any model of the formation of rich clusters: the uniformity of the ages of the stellar populations in the early-type galaxies and the universality of the metallicity sequence of these galaxies as a function of galaxy mass.
galaxies: active - galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: photometry - galaxies: stellar content