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We present results of N-body/gasdynamical simulations designed to investigate the evolution of X-ray clusters in a flat, low-density, cold dark matter (CDM) cosmogony. Ten clusters with mass in the range 8-16 × 10 14 M⊙/h were selected from a large cosmological simulation (with Ω0 = 0.3, Λ0 = 0.7 and h = 0.7), and resimulated at high resolution using an N-body/Smooth Particle Hydrodynamics code adapted to run on a GRAPE board. The simulations include self-gravity, pressure gradients and hydrodynamical shocks, but neglect radiative cooling. The density profile of the dark matter component can be fitted rather accurately by the simple formula originally proposed by Navarro, Frenk White to describe the structure of clusters in a CDM universe with Ω = 1. In projection, the shape of the dark matter radial density profile and the corresponding line-of-sight velocity dispersion profile are in very good agreement with the observed profiles for galaxies in the CNOC sample of clusters. The gas in our simulated clusters is less centrally concentrated than the dark matter, and its radial density profile is well described by the familiar β-model. As a result, the average baryon fraction within the virial radius (rvir) is only 85 − 90 % of the universal value and is lower nearer the center. The gas is approximately
Eke et al. (Thu,) studied this question.