GZK Photons Above 10 EeV

Understand

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.