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Abstract: The angular clustering of 5 Ultrahigh Energy Cosmic Rays UHECRs in thecombined published AGASA-HiRes data has a probability of ~ 2 10^-3 of occurringby chance. A first analysis of the implications of the event energies andangular spreading is presented, which is applicable if the source is closeenough that GZK losses can be ignored. Under this assumption, the observedenergies of the events in this cluster favor a bursting rather thancontinuously emitting source, with the events emitted on a time scale shortcompared with 300 D Mpc years. Assuming the UHECRs experience many incoherentsmall magnetic deflections enroute from source to Earth, the arrival directiondistribution allows estimation that < B^2 lambda > D ~ 7.7 nG^2 Mpc^2, wherelambda is the coherence length of the field and D is the source distance. Ifthe spectrum at the source ~ E^{-2}, the total isotropic equivalent energyemitted in UHECRs is > 10^43 D Mpc^3 ergs.



Author: Glennys R. Farrar

Source: https://arxiv.org/







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