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The ultra-high energy cosmic ray spectrum and Fermi shock acceleration

By M. Kachelriess and D.V. Semikoz


International audienceThe 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 > 1020 eV and have the steeply falling injection spectrum 1/E2.7, one can reproduce the measured cosmic ray flux above E > 1018 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/E2 predicted by Fermi shock acceleration. We study possible ways to distinguish between these two cases with future experiments

Topics: [ PHYS.ASTR.HE ] Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], [ SDU.ASTR.HE ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE]
Publisher: HAL CCSD
Year: 2007
OAI identifier: oai:HAL:hal-00713259v1
Provided by: Hal-Diderot
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