Gamma Rays from Ultra-High Energy Cosmic Rays in Cygnus A

Abstract

Ultra-high energy cosmic rays (UHECRs) accelerated in the jets of active galactic nuclei can accumulate in high magnetic field, ~100 kpc-scale regions surrounding powerful radio galaxies. Photohadronic processes involving UHECRs and photons of the extragalactic background light make ultra-relativistic electrons and positrons that initiate electromagnetic cascades, leading to the production of a gamma-ray synchrotron halo. We calculate the halo emission in the case of Cygnus A and show that it should be detectable with the Fermi Gamma ray Space Telescope and possibly detectable with ground-based gamma-ray telescopes if radio galaxies are the sources of UHECRs.

9 pages, 2 figures, extended calculations, added references; ApJL, in press

References in corpus (5)

• Observations of extended radio emission in clusters
• Search for Correlations between HiRes Stereo Events and Active Galactic Nuclei
• On the ultra-high energy cosmic ray horizon
• Multiwavelength study of Cygnus A I. Precession and slow jet speeds from radio observations
• Broadband X-ray spectrum of the newly discovered broad line radio galaxy IGR J21247+5058

Cited by in corpus (1)

• Ultra High Energy Cosmic Rays from Black Hole Jets of Radio Galaxies