A LOFAR-uGMRT spectral index study of distant radio halos G. Di Gennaro, R. J. van Weeren, R. Cassano, G. Brunetti, M. Brüggen, M. Hoeft, E. Osinga, A. Botteon, V. Cuciti, F. de Gasperin et al. (2 more) A&A, 654 (2021) A166 Published online: 27 October 2021 DOI: 10.1051/0004-6361/202141510