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Reconciling the ultra-high energy cosmic ray spectrum with Fermi shock acceleration

M. Kachelriess·D. V. Semikoz
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Abstract

The energy spectrum of ultra-high energy cosmic rays (UHECR) is usually calculated for sources with identical properties. Assuming that all sources can accelerate UHECR protons to the same extremely high maximal energy E_max > 10^{20} eV and have the steeply falling injection spectrum 1/E^{2.7}, one can reproduce the measured cosmic ray flux above E > 10^{18} eV. We show that relaxing the assumption of identical sources and using a power-law distribution of their maximal energy allows one to explain the observed UHECR spectrum with the injection 1/E^2 predicted by Fermi shock acceleration.

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M. Kachelriess, D. V. Semikoz. 2005-10-26. Reconciling the ultra-high energy cosmic ray spectrum with Fermi shock acceleration. https://doi.org/10.1016/j.physletb.2006.01.009

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