Study of Galaxy Cluster Properties from High-resolution Sph Simulations

We present some of the results of an ongoing collaboration to sudy the dynamical properties of galaxy clusters by means of high resolution adiabatic SPH cosmological simulations. Results from our numerical clusters have been tested against analytical models often used in X-ray observations: β model (isothermal and polytropic) and those based on universal dark matter profiles. We find a universal temperature profile, in agreement with AMR gasdynamical simulations of galaxy clusters. Temperature decreases by a factor 2-3 from the center to virial radius. Therefore, isothermal models (e.g. β model) give a very poor fit to simulated data. Moreover, gas entropy profiles deviate from a power law near the center, which is also in very good agreement with independent AMR simulations. Thus, if future X-ray observations confirm that gas in clusters has an extended isothermal core, then non-adiabatic physics would be required in order to explain it.