Radio relics are giant sources of diffuse synchrotron radio emission in the outskirts of galaxy clusters that are associated with shocks in the intracluster medium. Still, the origin of relativistic particles that make up relics is not fully understood. For most relics, diffusive shock acceleration (DSA) of thermal electrons is not efficient enough to explain observed radio fluxes. In this paper, we use a magnetohydrodynamic simulation of galaxy clusters in combination with Lagrangian tracers to simulate the formation of radio relics. Using a Fokker-Planck solver to compute the energy spectra of relativistic electrons, we determine the synchrotron emission of the relic. We find that re-acceleration of fossil electrons plays a major role in explaining the synchrotron emission of radio relics. Particles that pass through multiple shocks contribute significantly to the overall luminosity of a radio relic and greatly boost the effective acceleration efficiency. Furthermore, we find that the assumption that the luminosity of a radio relic can be explained with DSA of thermal electrons leads to an overestimate of the acceleration efficiency by a factor of more than 103

Smolinski D.C., Wittor D., Vazza F., Bruggen M. (2023). A multishock scenario for the formation of radio relics. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 526(3), 4234-4244 [10.1093/mnras/stad3009].

A multishock scenario for the formation of radio relics

Wittor D.;Vazza F.;Bruggen M.
2023

Abstract

Radio relics are giant sources of diffuse synchrotron radio emission in the outskirts of galaxy clusters that are associated with shocks in the intracluster medium. Still, the origin of relativistic particles that make up relics is not fully understood. For most relics, diffusive shock acceleration (DSA) of thermal electrons is not efficient enough to explain observed radio fluxes. In this paper, we use a magnetohydrodynamic simulation of galaxy clusters in combination with Lagrangian tracers to simulate the formation of radio relics. Using a Fokker-Planck solver to compute the energy spectra of relativistic electrons, we determine the synchrotron emission of the relic. We find that re-acceleration of fossil electrons plays a major role in explaining the synchrotron emission of radio relics. Particles that pass through multiple shocks contribute significantly to the overall luminosity of a radio relic and greatly boost the effective acceleration efficiency. Furthermore, we find that the assumption that the luminosity of a radio relic can be explained with DSA of thermal electrons leads to an overestimate of the acceleration efficiency by a factor of more than 103
2023
Smolinski D.C., Wittor D., Vazza F., Bruggen M. (2023). A multishock scenario for the formation of radio relics. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 526(3), 4234-4244 [10.1093/mnras/stad3009].
Smolinski D.C.; Wittor D.; Vazza F.; Bruggen M.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/956395
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