THE KINEMATICS OF DENSE CLUSTERS OF GALAXIES .3. COMPARISON WITH COSMOLOGICAL MODELS

We compare the combined distribution of 31 group and 25 cluster veloci ty dispersions [Zabludoff et al., AJ, 106, 1301 (1993)] with the ensem ble of 32 models for the formation and evolution of large-scale struct ure examined by Weinberg & Cole [MNRAS, 259, 652 (1999)]. The models i nclude Gaussian and non-Gaussian initial fluctuations, different power law spectra (n=-1, n=0, n=-2, ''pancake''), flat (OMEGA=1) and open ( OMEGA=0.2) cosmologies, and unbiased (b8= 1) and biased (b8=2) galaxy formation. The set of initial conditions we test, although limited, sa mples enough parameter space to indicate which general classes of mode ls are consistent with the data. The two Gaussian, n=-1 models which b est approximate the standard and open Cold Dark Matter (CDM) models do not match the observed distribution of velocity dispersions; models w ith b8=2 and OMEGA=1 (''standard'') or b8=1 and OMEGA=0.2 (''open'') p redict too large a ratio of low to high velocity dispersion systems. A ''COBE-normalized'' CDM model with b8=1 and OMEGA=1 produces clusters with velocity dispersions higher than those measured. All three model s overestimate the total abundance of systems.