Cosmic rays from active galactic nuclei

TL;DR

This paper investigates cosmic ray acceleration by shocks around active galactic nuclei, showing they significantly contribute to extragalactic cosmic rays with a specific energy spectrum extending up to 10^20 eV.

Contribution

It demonstrates that shocks from AGN cocoons are a primary source of extragalactic cosmic rays, complementing Galactic supernova remnants.

Findings

CR spectrum above 10^18 eV follows a power law with index ~2.6

CRs from AGN cocoons extend up to 10^20 eV

AGN cocoon shocks are a main source of extragalactic CRs

Abstract

Cosmic ray (CR) acceleration at the shock created by the expanding cocoons around active galactic nuclei (AGNs) is studied. It is shown that above the energy $10^{18}$ eV the overall energy spectrum of CRs, produced during the AGN evolution and released in the intergalactic space, has the form $N\propto \epsilon^{-\gamma}$, with $\gamma\approx 2.6$, which extends up to $\epsilon_{max}\sim 10^{20}$ eV. It is concluded that cocoons shocks have to be considered as a main source of extragalactic CRs, which together with Galactic supernova remnants provide the observed CR spectrum.