AN ANALYTIC MODEL OF THE PHYSICAL PROPERTIES OF GALAXY CLUSTERS

We introduce an analytic model of the diffuse intergalactic medium in galaxy clusters based on a polytropic equation of state for the gas in hydrostatic equilibrium with the cluster gravitational potential. This model is directly applicable to the analysis of X-ray and Sunyaev–Zel'dovich effect observations from the cluster core to the virial radius, with five global parameters and three parameters describing the cluster core. We validate the model using Chandra X-ray observations of two polytropic clusters, MS 1137.5+6625 and CL J1226.9+3332, and two cool core clusters, 1835 and A2204. We show that the model accurately describes the spatially resolved spectroscopic and imaging data, including the cluster core region where significant cooling of the plasma is observed.

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