A Giant Radio Halo in the Massive and Merging Cluster

We report on the detection of diffuse radio emission in the X-ray luminous and massive galaxy cluster A 1351 (z=0.322) using archival Very Large Array data at 1.4 GHz. Given its central location, morphology and Mpc-scale extent, we classify the diffuse source as a giant radio halo. X-ray and weak lensing studies show A 1351 to be a system undergoing a major merger. The halo is associated to the most massive substructure. The presence of this source is explained assuming that merger-driven turbulence may re-accelerate high energy particles in the intracluster medium and generate diffuse radio emission on the cluster scale. The position of A 1351 in the LogP1.4 GHz – LogLX plane is consistent with that of all other radio-halo clusters known to date, supporting a causal connection between the unrelaxed dynamical state of massive (> 10 M ) clusters and the presence of giant radio halos. Subject headings: acceleration of particles, galaxies: clusters: individual: A1351, radiation mechanisms: nonthermal, radio continuum: general X–rays: general