SUBSTRUCTURE IN CLUSTERS OF GALAXIES AND THE VALUE OF OMEGA

We investigate the formation of clusters of galaxies in an expanding u niverse using a new code that regrids at a region of high density. In particular, we investigate two models for the initial conditions, both with the standard cold dark matter (CDM) power spectrum - one has Ohm = 1, the other Ohm = 0.2. Both universes have H-0 = 100 km s(-1) Mpc( -1) and Lambda = 0. The level of substructure in the final cluster can be used as a discriminant of the cosmic density. We discuss various s tatistics that can be measured observationally from clusters of galaxi es, which can be used to discriminate between the two models. We find that most of the statistics that use the clusters' member galaxies may not be the best measures of substructure. Statistics that rely more o n X-ray maps and other observables depending more directly on the mass distribution could be better discriminants of Ohm.