Non-thermal vs. thermal SZ effect in galaxy clusters

Abstract

Many of the clusters in which SZ effects have been detected there is also evidence for radio halo sources and EUV or hard X-ray excesses. So it is of interest to assess whether the detected effects are in facts from the thermal or non-thermal electron populations. We present here the results of an exact derivation of the non-thermal SZ effect in galaxy clusters. Such a derivation is made using the full relativistic formalism and overcoming the limitations of the Kompaneets and of the single scattering approximations. We show that the spectral shape of the non-thermal SZ effect depends not only from the frequency but also from the cluster physical parameters, like the electron pressure, optical depth and temperature. We also evaluate the total SZ effect for a combination of thermal and non-thermal electron population residing in the same volume like is the case in radio-halo clusters. We discuss both the spectral and the spatial features of the non-thermal SZ effect considering two radio-halo clusters: A21...