Near-infrared properties of moderate-redshift galaxy clusters: Luminosity functions and density profiles

We present K-band imaging for 15 of the CNOC1 clusters. The extensive spectroscopic data set available for these clusters allows us to determine the cluster K-band luminosity function and density profile without the need for statistical background subtraction. The luminosity density and number density profiles can be described by NFW models with concentration parameters of c(l) 4.28 +/- 0.70 and c(g) 4.13 +/- 0.57, respectively. Comparing these to the dynamical mass analysis of the same clusters shows that they are similar to the cluster dark matter profile. The luminosity functions show that the evolution of K* over the redshift range 0.2 < z < 0.5 is consistent with a scenario in which the majority of stars in cluster galaxies form at high redshift (z(f) > 1: 5) and evolve passively thereafter. The best fit for the faint-end slope of the luminosity function is alpha = - 0.84 +/- 0.08, which indicates that it does not evolve between z = 0 and 0.3. Using principal component analysis of the spectra, we classify cluster galaxies as either starforming/ recently star-forming (EM+BAL) or non-star-forming ( ELL) and compute their respective luminosity functions. The faint-end slope of the ELL luminosity function is much shallower than for the EM+BAL galaxies at z = 0.3 and suggests that the number of faint ELL galaxies in clusters decreases by a factor of similar to 3 from z = 0 to 0.3. The redshift evolution of K* for both EM+BAL and ELL types is consistent with a passively evolving stellar population formed at high redshift. Passive evolution in both classes demonstrates that the bulk of the stellar population in all bright cluster galaxies is formed at high redshift, and subsequent transformations in morphology/color/spectral type have little effect on the total stellar mass.