The distant galaxy cluster CL0016+16: X-ray analysis up to R200

Abstract

Aims. CL0016+16 seems to be a good candidate for studying the mass distribution of galaxy clusters up to their Virial radius, since it is a bright massive cluster, previously considered as dynamically relaxed. Methods. Using XMM-Newton observations of CL0016+16, we performed a careful X-ray background analysis and detected its X-ray emission convincingly up to R 200 . We then studied its dynamical state with a detailed 2D temperature and surface brightness analysis of the inner part of the cluster. We used the assumption of both spherical symmetry and hydrostatic equilibrium (HE), to determine the main cluster parameters: total mass, temperature profile, surface brightness profile, and β-parameter. We also built a temperature map that clearly exhibits departure from spherical symmetry in the centre. To estimate the influence of these perturbations on our total mass estimate, we also computed the total mass in the framework of the HE approach, but this time with various temperature profiles obtained in different directions. Results. These various total-mass estimates are consistent with each other. The temperature perturbations are clear signatures of ongoing merger activity. We also find significant residuals after subtracting the emissivity map by a 2D /?-model fit. We conclude that, although CL0016+16 shows clear signs of merger activity and departure from spherical symmetry in the centre, its X-ray emissivity can be detected up to R 200 and the corresponding mass M 200 can be computed directly. It is therefore a good candidate for studying cosmological scaling laws as predicted by the theory.