Magnetic fields and relativistic electrons fill entire galaxy cluster

• DOI: 10.1126/sciadv.abq7623
• Publication Date: 2022-11-02T17:57:27Z
• Authors: Andrea Botteon; Reinout J. van We...; Gianfranco Brunetti; Franco Vazza; Timothy W. Shimwell; Marcus Brüggen; Huub J. A. Röttge...; Francesco de Gasp...; Hiroki Akamatsu; Annalisa Bonafede; Rossella Cassano; Virginia Cuciti; Daniele Dallacasa; Gabriella Di Gennaro; Fabio Gastaldello
• Keywords: High Energy Astrophysical Phenomena (astro-ph.HE); Earth, Environmental, Ecological, and Space Sciences; Cosmology and Nongalactic Astrophysics (astro-ph.CO); 0103 physical sciences; FOS: Physical sciences; Astrophysics - High Energy Astrophysical Phenomena; Astrophysics - Cosmology and Nongalactic Astrophysics; Astrophysics - High Energy Astrophysical Phenomena; 01 natural sciences; Astrophysics - Cosmology and Nongalactic Astrophysics

The hot plasma within merging galaxy clusters is predicted to be filled with shocks and turbulence that may convert part of their kinetic energy into relativistic electrons and magnetic fields generating synchrotron radiation. Analyzing Low Frequency Array (LOFAR) observations of the galaxy cluster Abell 2255, we show evidence of radio synchrotron emission distributed over very large scales of at least 5 megaparsec. The pervasive radio emission witnesses that shocks and turbulence efficiently transfer kinetic energy into relativistic particles and magnetic fields in a region that extends up to the cluster outskirts. The strength of the emission requires a magnetic field energy density at least 100 times higher than expected from a simple compression of primordial fields, presumably implying that dynamo operates efficiently also in the cluster periphery. It also suggests that nonthermal components may contribute substantially to the pressure of the intracluster medium in the cluster periphery.