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The number of cosmic rays measured as a function of energy by the AGASA collaboration (green points) is compared with the spectrum that would be expected if the particles were produced by a uniform distribution of cosmologically distant sources (red line).
The steep drop corresponds to the GZK cut-off. The AGASA data beyond this energy can be described by a model in which cosmic rays are generated locally by the decays of supermassive dark-matter particles in the galactic halo.