Abell 3560, a galaxy cluster at the edge of a major merging event

In this paper we study A3560, a rich cluster at the southern periphery of the A3558 complex, a chain of interacting clusters in the central part of the Shapley Concentration supercluster. From a ROSAT-PSPC map we find that the X-ray surface brightness distribution of A3560 is well described by two components, an elliptical King law and a more peaked and fainter structure, which has been modeled with a Gaussian. The main component, corresponding to the cluster, is elongated with the major axis pointing toward the A3558 complex. The second component, centered on the Dumb-bell galaxy which dominates the cluster, appears significantly offset (by ∼ 0.15 h−1 Mpc ) from the cluster X-ray centroid. From a Beppo-SAX observation we derive the radial temperature profile, finding that the temperature is constant (at kT ∼ 3.7 keV) up to 8 arcmin, corresponding to 0.3 h−1 Mpc : for larger distances, the temperature significantly drops to kT ∼ 1.7 keV. We analyze also temperature maps, dividing the cluster into 4 sectors and deriving the temperature profiles in each sector: we find that the temperature drop is more sudden in the sectors which point towards the A3558 complex. From VLA radio data, at 20 and 6 cm, we find a peculiar bright extended radio source (J1332-3308), composed of a core (centered on the northern component of the Dumb-bell galaxy), two lobes, a “filament” and a diffuse component. The morphology of the source could be interpreted either by a strong interaction of the radio source with the intracluster medium or by the model of intermittency of the central engine.