A simple parametric model for spherical galaxy clusters

Abstract

We present an analytic parametric model to describe the baryonic and dark matter distributions in clusters of galaxies with spherical symmetry. It is assumed that the dark matter density follows a Navarro, Frenk and White (NFW) profile and that the gas pressure is described by a generalised NFW (GNFW) profile. By further demanding hydrostatic equilibrium and that the gas fraction is small throughout the cluster, one obtains unique functional forms, dependent on basic cluster parameters, for the radial profiles of all the properties of interest in the cluster. We show these profiles are consistent both with numerical simulations and multi-wavelength observations of clusters. We also use our model to analyse six simulated SZ clusters as well as A611 SZ data from the Arcminute Microkelvin Imager (AMI). In each case, we derive the radial profile of the enclosed total mass and the gas pressure and show that the results are in good agreement with our model prediction.