SIMBAD references

K -band observations of the galaxy populations of three high-redshift (z = 0.8-1.0), X-ray-selected, massive clusters are presented. The observations reach a depth of K ≃ 21.5, corresponding to K *+ 3.5 mag. The evolution of the galaxy properties is discussed in terms of their K -band luminosity functions and the K -band Hubble diagram of brightest cluster galaxies (BCGs).

The bulk of the galaxy luminosities, as characterized by the parameter K * from the Schechter function, are found to be consistent with passive evolution with a redshift of formation of z_f~ 1.5-2. This is consistent with observations of other high-redshift clusters, but may be in disagreement with galaxies in the field at similar redshifts. A good match to the shape of the Coma cluster luminosity function is found by simply dimming the high-redshift luminosity function by an amount consistent with passive evolution. The evolution of the cumulative fraction of K -band light as a function of luminosity shows no evidence of merger activity in the brighter galaxies.

The evolution of the BCGs is tested by their K -band Hubble diagram and by the fraction of K -band cluster light in the BCGs. The evolution observed is consistent with recent previous observations although the scatter in the Hubble diagram allows for a range of evolutionary histories. The fraction of cluster light contained in the BCGs is not smaller than that in Coma, suggesting that they are already very massive with no need to hypothesize significant mergers in their futures.