A radio ridge connecting two galaxy clusters in a filament of the cosmic web
Brunetti, G.; Enßlin, T. A.; Shimwell, T. W.; Cassano, R.; Horellou, C.; Vazza, F.; van Weeren, R. J.; Röttgering, H. J. A.; Bonafede, A.; Govoni, F.; Brüggen, M.; de Gasperin, F.; Giovannini, G.; Ferrari, C.; Bernardi, G.; Paladino, R.; Hoeft, M.; Feretti, L.; Murgia, M.; Vacca, V.; Iacobelli, M.; Scaife, A. M. M.; Loi, F.; Wise, M.; Pizzo, R. F.; Gheller, C.; Orrù, E.; Manti, S.; Junklewitz, H.
Italy, Netherlands, South Africa, France, Switzerland, Germany, Sweden, United Kingdom
Abstract
Galaxy clusters are the most massive gravitationally bound structures in the Universe. They grow by accreting smaller structures in a merging process that produces shocks and turbulence in the intracluster gas. We observed a ridge of radio emission connecting the merging galaxy clusters Abell 0399 and Abell 0401 with the Low-Frequency Array (LOFAR) telescope network at 140 megahertz. This emission requires a population of relativistic electrons and a magnetic field located in a filament between the two galaxy clusters. We performed simulations to show that a volume-filling distribution of weak shocks may reaccelerate a preexisting population of relativistic particles, producing emission at radio wavelengths that illuminates the magnetic ridge.