Ultrahigh-energy nuclei, photons, and magnetic fields

Abstract

Combined recent data from cosmic-ray detectors and gamma-ray detectors have produced some surprising insights regarding the sources of ultrahigh-energy cosmic rays (UHECRs), magnetic fields inside and outside the Milky Way, and the universal photon backgrounds. The energy-dependent composition of UHECRs implies a non-negligible contribution of sources located in the Milky Way, such as past gamma-ray bursts that took place in our Galaxy. Extended halos of distant sources seen in the Fermi data imply that intergalactic magnetic fields have average strengths of the order of a femtogauss. Such relatively low magnetic fields imply that the protons from distant blazars generate a detectable flux of secondary gamma rays in their interactions with the photon background. A comparison with the data shows an excellent agreement of the secondary photons with the spectra of distant blazars observed by atmospheric Cherenkov telescopes.

6 pages, 3 figures, talk presented at "Cosmic Ray International Seminar (CRIS 2010)", Catania, September, 13-17, 2010

References in corpus (5)

• Long gamma-ray bursts and core-collapse supernovae have different environments
• IceCube: An Instrument for Neutrino Astronomy
• GRBs as Cosmological Probes - Cosmic Chemical Evolution
• High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae
• The spatial energy spectrum of magnetic fields in our Galaxy

Cited by in corpus (2)

• Non-parametric Bayesian reconstruction of Galactic magnetic fields using Information Field Theory: The inclusion of line-of-sight information in ultra-high energy cosmic ray backtracking
• Cosmic connections: from cosmic rays to gamma rays, to cosmic backgrounds and magnetic fields