Related papers: Clusters in Various Cosmological Models: Abundance…
Summary - By combining the 5634 redshifts from the ESO Nearby Abell Cluster Survey (the ENACS) with another 1000 redshifts from the literature we are able to study the distribution of velocity dispersions for a volume-limited sample of 128…
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…
Evolution of the cluster population has been recognized as a powerful cosmological tool. While the present--day abundance of X-ray clusters is degenerate in $\sigma_8$, $n$ and $\Omega_0$, Oukbir and Blanchard (1992, 1997) have pointed out…
The evolution of the galaxy cluster abundance depends sensitively on the value of the cosmological density parameter, Omega_0. Recent ASCA data are used to quantify this evolution as measured by the X-ray temperature function. A chi^2…
The population of rich galaxy clusters evolves much more rapidly in a universe with critical density than one with low density, thus offering the possibility of determining the cosmological density parameter, Omega_0. We quantify this…
In nearby clusters early-type galaxies follow isotropic orbits, while the orbits of late-type galaxies are characterized by slightly radial anisotropy. Little is known about the orbits of the different populations of cluster galaxies at…
We show that the evolution of the number density of rich clusters of galaxies breaks the degeneracy between Omega (the mass density ratio of the universe) and sigma_{8} (the normalization of the power spectrum), sigma_{8}Omega^{0.5} \simeq…
We present the first dynamical study of the optically selected Palomar Distant Cluster Survey (PDCS). We show that eleven out of twelve PDCS clusters we observed are real over-densities of galaxies. Most clusters have velocity dispersions…
The evolution of the abundance of galaxy clusters is not a reliable measure of Omega if there are features on scales of a few Mpc in the primordial power spectrum. Conversely, if we know the cosmological model parameters from other…
We summarize several results based on the velocity data-set for cluster galaxies provided by ENACS (the ESO Nearby Abell Cluster Survey). We describe the distribution of velocity dispersions of a complete sample of rich galaxy clusters, and…
We present a detailed model of the absolute number counts, color and redshift distributions of gravitational arclets observed in clusters of galaxies. The framework adopted for galaxy evolution is chosen to fairly reproduce the observed…
We revisit the issue of the recent dynamical evolution of clusters of galaxies using a sample of ACO clusters with z<0.14, which has been selected such that it does not contain clusters with multiple velocity components nor strongly merging…
We study the evolution of galaxies in clusters by the analysis of a sample of about 3000 galaxies, members of 59 clusters from the ESO Nearby Abell Cluster Survey (ENACS). We distinguish four cluster galaxy populations, based on their…
We apply a unique gas fraction estimator to published X-ray cluster properties and we compare the derived gas fractions of observed clusters to simulated ones. The observations are consistent with a universal gas fraction of…
In this paper we investigate the velocity dispersion profiles of clusters of galaxies for seven cosmological models. One model is the SCDM model, and the others are six low-density models with the density parameter $\Omega=0.1$, 0.2 or 0.3…
We present the results of the analysis of the internal velocity dispersions, \sigma_v, for the CNOC sample of distant galaxy clusters, based on an interlopers removal algorithm, which is different from that originally applied by Carlberg et…
In gaussian theories of structure formation, the galaxy cluster abundance is an extremely sensitive probe of the density fluctuation power spectrum and of the density parameter, $\Omega$. We develop this theme by deriving and studying in…
We consider a sample of 51 distant galaxy clusters at 0.15<z<0.9 (<z> about 0.3), each cluster having at least 10 galaxies with available redshift in the literature. We select member galaxies, analyze the velocity dispersion profiles, and…
Measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem. We have developed a new technique which uses photometric redshifts to measure the angular correlation function in redshift shells.…
Measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem. For a two-dimensional galaxy catalog, however, we can measure the galaxy-galaxy angular correlation function which provides…