ABSTRACT. Using K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters we examine the near-infrared properties of moderate-redshift (0.19 < z < 0.55) galaxy clusters. We find that the number of K-band selected cluster galaxies within R₅₀₀ (the halo occupation number, HON) is well correlated with the cluster dynamical mass (M ₅₀₀) and X-ray temperature (T_X); however, the intrinsic scatter in these scaling relations is 37% and 46%, respectively. Comparison with clusters in the local universe shows that the HON-M₅₀₀ relation does not evolve significantly between z = 0 and z ~ 0.3. This suggests that if dark matter halos are disrupted or undergo significant tidal stripping in high-density regions as seen in numerical simulations, the stellar mass within the halos is tightly bound, and not removed during the process. The total K-band cluster light (L_200,K) and K-band-selected richness (parameterized by B_gc,K) are also correlated with both the cluster T_X and M₂₀₀. The total (intrinsic) scatter in the L_200,K-M₂₀₀ and B_gc,K-M₂₀₀ relations are 43% (31%) and 35% (18%), respectively, and indicates that for massive clusters both L_200,K and B_gc,K can predict M₂₀₀ with accuracy similar to that of T_X, L_X, or optical richness (B_gc). Examination of the mass-to-light ratios of the clusters shows that similarly to local clusters, the K-band mass-to-light ratio is an increasing function of halo mass. Using the K-band mass-to-light ratios of the clusters, we apply the Oort technique and find Ω_m,0 = 0.22 ± 0.02, which agrees well with recent combined concordance cosmology parameters, but, similarly to previous cluster studies, is on the low-density end of preferred values.

Subject headings: dark matter; galaxies: clusters: general; galaxies: fundamental parameters; galaxies: photometry; large-scale structure of universe

Print publication: Issue 1 (2007 July 1)
Received 2006 December 8, accepted for publication 2007 March 12