Constraints on top-down models for the origin of UHECRs from the Pierre Auger Observatory data
Abstract
In the context of the report by the AGASA experiment of an apparent excess in the cosmic ray flux above the energy of the expected GZK feature, a variety of "top-down models" have been proposed for the origin of ultra-high-energy cosmic rays (UHECRs). These models involve the decay of supermassive particles and generically predict high neutrino and photon fluxes at ultra-high energy. Relying on the corresponding flux limits and overall spectrum normalisation obtained by the Pierre Auger Observatory, we set constraints on a wide class of top-down models and their contribution to the UHECR flux.