The build‐up of the colour–magnitude relation in galaxy clusters since z∼ 0.8

School of Physics and Astronomy, University of Nottingham, Nottigham, England, United Kingdom
Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.11). 01/2007; 374(3):809 - 822. DOI: 10.1111/j.1365-2966.2006.11199.x
Source: arXiv


Using galaxy clusters from the ESO Distant Cluster Survey, we study how the distribution of galaxies along the colour–magnitude relation has evolved since z∼ 0.8. While red-sequence galaxies in all these clusters are well described by an old, passively evolving population, we confirm our previous finding of a significant evolution in their luminosity distribution as a function of redshift. When compared to galaxy clusters in the local Universe, the high-redshift EDisCS clusters exhibit a significant deficit of faint red galaxies. Combining clusters in three different redshift bins, and defining as ‘faint’ all galaxies in the range 0.4 ≳L/L*≳ 0.1, we find a clear decrease in the luminous-to-faint ratio of red galaxies from z∼ 0.8 to ∼0.4. The amount of such a decrease appears to be in qualitative agreement with predictions of a model where the blue bright galaxies that populate the colour–magnitude diagram of high-redshift clusters, have their star formation suppressed by the hostile cluster environment. Although model results need to be interpreted with caution, our findings clearly indicate that the red-sequence population of high-redshift clusters does not contain all progenitors of nearby red-sequence cluster galaxies. A significant fraction of these must have moved on to the red sequence below z∼ 0.8.

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