The XMM Cluster Survey: The build up of stellar mass in Brightest Cluster Galaxies at high redshift

Understand

We present deep J and Ks band photometry of 20 high redshift galaxy clusters between z=0.8-1.5, 19 of which are observed with the MOIRCS instrument on the Subaru Telescope.

• By using near-infrared light as a proxy for stellar mass we find the surprising result that the average stellar mass of Brightest Cluster Galaxies (BCGs) has remained constant at ~9e11MSol since z~1.5.
• We investigate the effect on this result of differing star formation histories generated by three well known and independent stellar population codes and find it to be robust for reasonable, physically motivated choices of age and metallicity.
• By performing Monte Carlo simulations we find that the result is unaffected by any correlation between BCG mass and cluster mass in either the observed or model clusters.