GZK Photons as Ultra High Energy Cosmic Rays

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dc.creatorGelmini, Graciela B.
dc.creatorKalashev, Oleg E.
dc.creatorSemikoz, Dmitry V.
dc.date2005-06-06
dc.date2007-11-01
dc.date.accessioned2026-07-07T11:57:12Z
dc.date.available2026-07-07T11:57:12Z
dc.descriptionWe calculate the flux of "GZK-photons", namely the flux of Ultra High Energy Cosmic Rays (UHECR) consisting of photons produced by extragalactic nucleons through the resonant photoproduction of pions, the so called GZK effect. We We calculate the flux of "GZK-photons", namely the flux of Ultra High Energy Cosmic Rays (UHECR) consisting of photons produced by extragalactic nucleons through the resonant photoproduction of pions, the so called GZK effect. We show that, for primary nucleons, the GZK photon fraction of the total UHECR flux is between $10^{-4}$ and $10^{-2}$ above $10^{19}$ eV and up to the order of 0.1 above $10^{20}$ eV. The GZK photon flux depends on the assumed UHECR spectrum, slope of the nucleon flux at the source, distribution of sources and intervening backgrounds. Detection of this photon flux would open the way for UHECR gamma-ray astronomy. Detection of a larger photon flux would imply the emission of photons at the source or new physics. We compare the photon fractions expected for GZK photons and the minimal predicted by Top-Down models. We find that the photon fraction above $10^{19}$ eV is a crucial test for Top-Down models.
dc.description21 pages, 18 figures with 35 panels in version 3 (substantial changes to the "Topological defects", "SHDM" and "Photon fractions" subsections were made with respect to version 2)
dc.identifierhttps://arxiv.org/abs/astro-ph/0506128
dc.identifierhttp://arxiv.org/abs/astro-ph/0506128
dc.identifierJ.Exp.Theor.Phys.106:1061-1082,2008
dc.identifierdoi:10.1134/S106377610806006X
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/205800
dc.subjectAstrophysics
dc.titleGZK Photons as Ultra High Energy Cosmic Rays
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