Ultra-high energy cosmic rays from radio galaxies revisited

Abstract

A striking concentration of ultra-high energy cosmic ray (UHECR) events observed by the Pierre Auger Observatory around the direction of the nearby radio galaxy Centaurus A revives the idea that radio galaxies may be dominant sources of UHECR. In this paper, we give a brief overview about processes which may accelerate protons and nuclei in radio galaxies, and their relation to jet power, radio morphology and cosmic source density. We argue that, except for the most powerful FR-II radio galaxies, processes in radio lobes are unlikely to explain the origin of UHECR. However, Fermi acceleration of protons at internal shocks in the "blazarzone" of all radio galaxies, and their photohadronic conversion into neutrons, may lead to the ejection of "UHECR-beams", which remain collimated over several Mpc. Consequences of this hypothesis for the interpretation of the UHECR event distribution, in particular for the special case of Centaurus A, are discussed.

5 pages, 1 figure; paper contributed to the XXth Rencontres de Blois, "Challenges in Particle Astrophysics"

References in corpus (2)

• High energy radiation from Centaurus A
• Status and prospects of the IceCube neutrino telescope

Cited by in corpus (8)

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• Neutrinos from active black holes, sources of ultra high energy cosmic rays
• Magnetic Deflections of Ultra-High Energy Cosmic Rays from Centaurus A
• UHECR observations and lensing in the magnetic field of the Virgo cluster
• Active Galactic Nuclei: Sources for ultra high energy cosmic rays?
• Magnetically Induced Anisotropies in the Arrival Directions of Ultra-high-energy Cosmic Rays from Nearby Radio Galaxies