A comparison of radio and X-ray morphologies of four clusters of galaxies containing radio halos

Clusters of galaxies may contain cluster-wide, centrally located, diffuse radio sources, called halos. They have been found to show morphologies similar to those of the X-ray emission. To quantify this qualitative statement we performed a point-to-point comparison of the ratio and the X-ray emission for four clusters of galaxies containing radio halos: Coma: Abell 2255, Abell 2319, Abell 2744. Our study leads to a linear relation between the radio and the X-ray sur surface brightness in tao clusters, namely Abell 2255 and Abell 2744. In Coma and A2319 the radio and the X-ray brightnesses seem to be: related with a sub-linear power law. Implications of these findings within simple radio halo formation models are briefly discussed.