Cosmic horizon for GeV sources and photon-photon scattering
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Photon-photon scattering of gamma-rays on the cosmic microwave background has been studied using the low energy approximation of the total cross section by Zdziarski and Svensson (Astrophys. J. 344:551, 1989), Svensson and Zdziarski (Astrophys. J. 349:415, 1990). Here, the cosmic horizon due to photon-photon scattering is accurately determined using the exact cross section and we find that photon-photon scattering dominates over the pair production at energies smaller than 1.68 GeV and at redshifts larger than 180.
KeywordsCosmic rays Background radiation
I would like to thank the anonymous referee for his/her remarks and suggestions which improved presentation of this paper.
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