Spectral index image of the radio halo in the cluster Abell 520, which hosts the famous bow shockV. Vacca, L. Feretti, G. Giovannini, F. Govoni, M. Murgia, R. A. Perley and T. E. ClarkeA&A, 561 (2014) A52DOI: https://doi.org/10.1051/0004-6361/201322504
