CLUSTERS AND GROUPS OF GALAXIES AS COSMOLOGICAL PROBES

N-body simulation data of cold dark matter (CDM) cosmogonies are examined in order to investigate the effect of the density parameter OMEGA on several properties of the groups and clusters of galaxies identified from the simulations. Specifically we consider two spatially flat CDM models; (OMEGA, lambda, h, b(rho)) = (1.0, 0.0, 0.5, 2.5) and (0.2, 0.8, 1.0, 1.0), where lambda, h, and b(rho) are the dimensionless cosmological constant, the Hubble constant in units of 100 km s-1 Mpc-1, and the biasing parameter. We computed the mass function, two-point correlation functions in real and redshift spaces, velocity correlation functions, velocity distribution functions, and the peculiar velocity field around the clusters. The overall conclusion is that the OMEGA = 1.0 CDM model generally fails to reproduce the observed properties of the clusters of galaxies as has been claimed recently from various independent analyses, while the OMEGA = 0.2 CDM model is quite successful.