Cosmic ray acceleration to ultrahigh energy in radio galaxies
University of Oxford, Astrophysics, Keble Road, Oxford, OX1 3RH, UK
2 University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
3 Astronomical Institute, Academy of Sciences of the Czech Republic, Boční II1401, CZ-141 00 Prague, Czech Republic
4 ELI Beamlines, Institute of Physics, Czech Academy of Sciences, 25241 Dolní Břežany, Czech Republic
* e-mail: email@example.com
Published online: 17 May 2019
The origin of ultrahigh energy cosmic rays (UHECRs) is an open question. In this proceeding, we first review the general physical requirements that a source must meet for acceleration to 10-100 EeV, including the consideration that the shock is not highly relativistic. We show that shocks in the backflows of radio galaxies can meet these requirements. We discuss a model in which giant-lobed radio galaxies such as Centaurus A and Fornax A act as slowly-leaking UHECR reservoirs, with the UHECRs being accelerated during a more powerful past episode. We also show that Centaurus A, Fornax A and other radio galaxies may explain the observed anisotropies in data from the Pierre Auger Observatory, before examining some of the difficulties in associating UHECR anisotropies with astrophysical sources.
© The Authors, published by EDP Sciences, 2019
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