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arXiv · 2210.01591

Life cycle of cosmic-ray electrons in the intracluster medium

F. Vazza·D. Wittor·L. Di Federico·M. Brüggen·M. Brienza·G. Brunetti·F. Brighenti·T. Pasini
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Abstract

We simulate the evolution of relativistic electrons injected into the medium of a small galaxy cluster by a central radio galaxy, studying how the initial jet power affects the dispersal and the emission properties of radio plasma. By coupling passive tracer particles to adaptive-mesh cosmological MHD simulations, we study how cosmic-ray electrons are dispersed as a function of the input jet power. We also investigate how the latter affects the thermal and non-thermal properties of the intracluster medium, with differences discernible up to $\sim$ Gyr after the start of the jet. We evolved the energy spectra of cosmic-ray electrons, subject to energy losses that are dominated by synchrotron and inverse Compton emission as well as energy gains via re-acceleration by shock waves and turbulence. We find that in the absence of major mergers the amount of re-acceleration experienced by cosmic-ray electrons is not enough to produce long-lived detectable radio emissions. However, for all simulations the role of re-acceleration processes is crucial to maintain a significant and volume-filling reservoir of fossil electrons ($\gamma \sim 10^3$) for several Gyrs after the first injection by jets. This is important to possibly explain recent discoveries of cluster-wide emission and other radio phenomena in galaxy clusters.

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F. Vazza, D. Wittor, L. Di Federico, M. Brüggen, M. Brienza, G. Brunetti, F. Brighenti, T. Pasini. 2022-10-03. Life cycle of cosmic-ray electrons in the intracluster medium. https://doi.org/10.1051/0004-6361%2F202243753

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