A Powerful Radio Halo in the Hottest Known Cluster of Galaxies 1E0657-56
  We report the detection of a diffuse radio halo source in the hottest known cluster of galaxies 1E0657-56 (RXJ0658-5557). The radio halo has a morphology similar to the X-ray emission from the hot intracluster medium. The presence of a luminous radio halo in such a hot cluster is further evidence for a steep correlation between the radio halo power and the X-ray temperature. We favour models for the origin of radio halo sources involving a direct connection between the X-ray emitting thermal particles and the radio emitting relativistic particles. 
H. Liang, R. W. Hunstead, M. Birkinshaw, P. Andreani