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R. I. Epstein (Los Alamos National Laboratory), P. Blasi (University of Chicago), A. V. Olinto (University of Chicag)
The long-held notion that the highest-energy cosmic rays are of distant extragalactic origin is challenged by observations that events above 1020 eV do not exhibit the expected GZK cutoff. We suggest that these ultra-high-energy events may be due to iron nuclei accelerated from young, strongly magnetic neutron stars. Newly formed pulsars accelerate ions from their surface through relativistic MHD winds. We find that pulsars whose initial spin periods are shorter than ~10 ms and whose surface magnetic exceed ~1013 G can accelerate iron ions to greater than 1020 eV. These ions can pass through the remnant of the supernova explosion that produced the pulsar without suffering significant spallation reactions. We are exploring models of the galactic magnetic field for which the trajectories of the iron ions from galactic sources are consistent with the observed arrival directions of the highest energy events.
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