GZK Photons in the Minimal Ultra High Energy Cosmic Rays Model

Abstract

In a recently proposed model the cosmic rays spectrum at energies above 10^{18} eV can be fitted with a minimal number of unknown parameters assuming that the extragalactic cosmic rays are only protons with a power law source spectrum ~E^{-alpha} and alpha~2.6. Within this minimal model, after fitting the observed HiRes spectrum with four parameters (proton injection spectrum power law index and maximum energy, minimum distance to sources and evolution parameter) we compute the flux of ultra-high energy photons due to photon-pion production, the GZK photons, for several radio background models and average extragalactic magnetic fields with amplitude between 10^{-11} G and 10^{-9} G. We find the photon fraction to be between 10^{-4} and 10^{-3} in cosmic rays at energies above 10^{19} eV. These small fluxes could only be detected in future experiments like Auger North plus South and EUSO.

13 pages, 9 figures

References in corpus (3)

• Upper limit on the ultra-high-energy photon flux from AGASA and Yakutsk data
• Constraining the fraction of primary gamma rays at ultra-high energies from the muon data of the Yakutsk extensive-air-shower array
• Is astronomy possible with neutral ultra-high energy cosmic ray particles existing in the Standard Model?

Cited by in corpus (6)

• Cosmogenic photons as a test of ultra-high energy cosmic ray composition
• Ultra-High-Energy Cosmic Rays from the Radio Lobes of AGNs
• Non-Universal Spectra of Ultra-High Energy Cosmic Ray Primaries and Secondaries in a Structured Universe
• High energy cosmic rays
• Composition of UHECR and the Pierre Auger Observatory Spectrum
• Towards a model of population of astrophysical sources of ultra-high-energy cosmic rays