A radio ridge connecting two galaxy clusters in a filament of the cosmic web.

Govoni, F; Orrù, E; Bonafede, A; Iacobelli, M; Paladino, R; Vazza, F; Murgia, M; Vacca, V et al. · Science · 2019

basic_science · Level V

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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.