Greisen Zatsepin Kuzmin photons above 10 EeV

G. Gelmini (1) , O. Kalashev (2) , D.V. Semikoz (3)

1 Department of Physics and Astronomy [UCLA, Los Angeles]
2 INR - Institute for Nuclear Research of Russian Academy of Sciences
3 APC - THEORIE

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 ultrahigh energy cosmic rays (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 make calculations for 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 per cent and as low as 10-4 above 1019 eV. For nuclei produced at the sources the maximum photon fraction is a factor of 2 3 times smaller above 1019 eV but the minimum could be much smaller than for nucleons. We also comment on cosmogenic neutrino fluxes.

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Phénomènes cosmiques de haute energie [astro-ph.HE]

G. Gelmini, O. Kalashev, D.V. Semikoz. Greisen Zatsepin Kuzmin photons above 10 EeV. Journal of Cosmology and Astroparticle Physics, 2007, 11, pp.002. ⟨10.1088/1475-7516/2007/11/002⟩. ⟨hal-00713200⟩