Upper limit on the primary photon fraction from the Pierre Auger Observatory

The Pierre Auger Collaboration

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Upper limit on the primary photon fraction from the Pierre Auger Observatory

The Pierre Auger Collaboration

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Abstract

Based on observations of the depth of shower maximum performed with the hybrid detector of the Auger Observatory, an upper limit on the cosmic-ray photon fraction of 26% (at 95% confidence level) is derived for primary energies above 10^19 eV. Additional observables recorded with the surface detector array, available for a sub-set of the data sample, support the conclusion that a photon origin of the observed events is not favoured.

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The Pierre Auger Collaboration. 2005-07-18. Upper limit on the primary photon fraction from the Pierre Auger Observatory. https://arxiv.org/abs/astro-ph/0507402

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