Generation of 10^15 - 10^17 eV photons by UHE CR in the Galactic magnetic filed

Abstract

We show that the deep expected in the diffuse photon spectrum above the threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be absent due to the synchrotron radiation by the electron component of the extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic filed. The mechanism we propose requires small (less than 2x10^-12 G) extragalactic magnetic fields and large fraction of photons in the UHE CR. For a typical photon flux expected in top-down scenarios of UHE CR, the predicted flux in the region of the deep is close to the existing experimental limit. The sensitivity of our mechanism to the extragalactic magnetic field may be used to improve existing bounds on the latter by two orders of magnitude.

11 pages, LaTeX, 1 .ps figure. Numerical error corrected; references added

References in corpus (6)

• Extension of the Cosmic-Ray Energy Spectrum Beyond the Predicted Greisen-Zatsepin-Kuz'min Cutoff
• Origin and Propagation of Extremely High Energy Cosmic Rays
• Limits on the Isotropic Diffuse Flux of Ultrahigh Energy Gamma-Radiation
• Cosmic Magnetic Fields in Large Scale Filaments and Sheets
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