GZK Photons Above 10 EeV

Abstract

We calculate the flux of "GZK-photons", namely the flux of photons produced by extragalactic nucleons through the resonant photoproduction of pions, the so called GZK effect. This flux depends on the UHECR spectrum on Earth, of the spectrum of nucleons emitted at the sources, which we characterize by its slope and maximum energy, on the distribution of sources and on the intervening cosmological backgrounds, in particular the magnetic field and radio backgrounds. For the first time we calculate the GZK photons produced by nuclei. We calculate the possible range of the GZK photon fraction of the total UHECR flux for the AGASA and the HiRes spectra. We find that for nucleons produced at the sources it could be as large as a few % and as low as 10^{-4} above 10 EeV. For nuclei produced at the sources the maximum photon fraction is a factor of 2 to 3 times smaller above 10 EeV but the minimum could be much smaller than for nucleons. We also comment on cosmogenic neutrino fluxes.

20 pages, 9 figures (21 panels), iopart.cls and iopart12.clo needed to typeset

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• An upper limit to the photon fraction in cosmic rays above 10^19 eV from the Pierre Auger Observatory
• Search for ultra-high energy photons using air showers
• Upper limit on the ultra-high-energy photon flux from AGASA and Yakutsk data
• Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data
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Cited by in corpus (18)

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• Extragalactic propagation of ultrahigh energy cosmic-rays
• Search for Anisotropy of Ultra-High Energy Cosmic Rays with the Telescope Array Experiment
• Gamma-Ray Constraints on Maximum Cosmogenic Neutrino Fluxes and UHECR Source Evolution Models
• Upper limit on the flux of photons with energies above 10^19 eV using the Telescope Array surface detector
• Cosmogenic gamma-rays and the composition of cosmic rays
• Ultra-High Energy Cosmic Rays and the GeV-TeV Diffuse Gamma-Ray Flux
• Constraints on the origin of ultra-high-energy cosmic rays from cosmogenic neutrinos and photons
• Constraints on the flux of primary cosmic-ray photons at energies E > 10^18 eV from Yakutsk muon data
• Sensitivity of cosmic-ray experiments to ultra-high-energy photons: reconstruction of the spectrum and limits on the superheavy dark matter
• Ultra high energy photons as probes of Lorentz symmetry violations in stringy space-time foam models
• Quantum Gravity phenomenology: achievements and challenges
• High energy cosmic rays
• UHECR mass composition at highest energies from anisotropy of their arrival directions
• Double Pair Production by Ultra High Energy Cosmic Ray Photons
• Estimating $\gamma \gamma$ absorption for UHE photons with lepton and hadron production