Summing up Ultra-High-Energy Cosmic Rays from Radio Galaxies

Abstract

Radio galaxies are intensively discussed as the sources of cosmic rays observed above about 3 EeV, called ultra-high-energy cosmic rays (UHECRs). Here, the key issues from a recent investigation are summed up, where the individual characteristics of radio galaxies, as well as the impact by the extragalactic magnetic-field structures up to a distance of 120 Mpc has been taken into account. It is shown that the average contribution of radio galaxies taken over a very large volume cannot explain the observed features of UHECRs measured at Earth. However, we obtain excellent agreement with the spectrum, composition, and arrival-direction distribution of UHECRs measured by the Pierre Auger Observatory, if we assume that most UHECRs observed arise from only two sources: The ultra-luminous radio galaxy Cygnus A, providing a mostly light composition of nuclear species dominating up to about 60 EeV, and the nearest radio galaxy Centaurus A, providing a heavy composition dominating above 60 EeV. Here we have to assume that extragalactic magnetic fields out to 250 Mpc, which we did not include in the simulation, are able to isotropize the UHECR events at about 8 EeV arriving from Cygnus A.

References in corpus (13)

• First Observation of the Greisen-Zatsepin-Kuzmin Suppression
• A New Model of the Galactic Magnetic Field
• Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
• The emission line - radio correlation for radio sources using the 7C Redshift Survey
• Measurement of the energy spectrum of cosmic rays above 10^18 eV using the Pierre Auger Observatory
• Observation of a Large-scale Anisotropy in the Arrival Directions of Cosmic Rays above $8\times 10^{18}$ eV
• Radio sources in the 6dFGS: Local luminosity functions at 1.4 GHz for star-forming galaxies and radio-loud AGN
• Constrained Simulations of the Magnetic Field in the Local Universe and the Propagation of UHECRs
• CRPropa 3 - a Public Astrophysical Simulation Framework for Propagating Extraterrestrial Ultra-High Energy Particles
• Ultra-High Energy Cosmic Ray Probes of Large Scale Structure and Magnetic Fields
• Radio galaxies of the local universe: all-sky catalog, luminosity functions, and clustering
• Ultra-High-Energy Cosmic Rays from Radio Galaxies
• Ultra-High Energy Cosmic Rays from Centaurus A: Jet Interaction with Gaseous Shells

Cited by in corpus (1)

• Particle acceleration in radio galaxies with flickering jets: GeV electrons to ultrahigh energy cosmic rays