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Redshift Evolution of Galaxy Cluster Densities | | R. G. Carlberg
; S. L. Morris
; H. K. C. Yee
; E. Ellingson
; | | Date: |
17 Dec 1996 | | Subject: | astro-ph | | Abstract: | The number of rich galaxy clusters per unit volume is a strong function of Omega, the cosmological density parameter, and sigma_8, the linear extrapolation to z=0 of the density contrast in 8/h Mpc spheres. The CNOC cluster redshift survey provides a sample of clusters whose average mass profiles are accurately known, which enables a secure association between cluster numbers and the filtered density perturbation spectrum. We select from the CNOC cluster survey those EMSS clusters with bolometric L_x>=10^45 erg/s and a velocity dispersion exceeding 800 km/s in the redshift ranges 0.18-0.35 and 0.35-0.55. We compare the number density of these subsamples with similar samples at both high and low redshift. Using the Press-Schechter formalism and CDM style structure models, the density data are described with sigma_8=0.75+/-0.1 and Omega=0.4+/-0.2 (90% confidence). The cluster dynamical analysis gives Omega=0.2+/-0.1$ for which sigma_8=0.95+/-0.1 (90% confidence). The predicted cluster density evolution in an Omega=1 CDM model exceeds that observed by more than an order of magnitude. | | Source: | arXiv, astro-ph/9612169 | | Services: | Forum | Review | PDF | Favorites | |
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