Internal Velocity and Mass Distributions in Clusters of Galaxies for a Variety of Cosmogonic Models

The mass and velocity distributions in the outskirts (0.5 − 3.0hMpc) of clusters of galaxies are examined for a suite of cosmogonic models utilizing largescale Particle-Mesh (PM) simulations (500 cells, 250 particles and box size of 100hMpc, giving a nominal resolution of 0.2hMpc with the true resolution about 0.5hMpc). Through a series of model computations, designed to isolate the different effects, we find that both Ω0 and Pk (λ ≤ 16hMpc) are important to the mass distributions in clusters of galaxies. There is a correlation between power, Pk, and density profiles of massive mass clusters; more power tends to point to the direction of a correlation between α and M(r < 1.5hMpc) [see equation (1) for definitions], i.e., massive clusters being relatively extended and small mass clusters being relatively concentrated. A lower Ω0 universe tends to produce relatively concentrated massive clusters and relatively extended small mass clusters compared to their counterparts in a higher Ω0 model with the same power. Models with little (initial) small scale power, such as the HDM model, produce more extended mass distributions than the isothermal distribution for most of the clusters. But the CDM models show mass distributions of most of the clusters more concentrated than the isothermal distribution. X-ray and gravitational lensing observations are begining providing useful information on the mass distribution in and around clusters; some interesting constraints on Ω0 and/or the (initial) power of the density fluctuations on scales λ ≤ 16hMpc (where linear extrapolation is invalid) can be obtained when larger observational data sets, such as the planned Sloan Digital Sky Survey, become available. With regard to the velocity distribution, we find two interesting points. First, in 0.5 < r < 3.0hMpc region, velocity dispersions of four components, (1d, radial,