Origin of the ankle in the ultra-high energy cosmic ray spectrum and of the extragalactic protons below it

2015/12/01 by Glennys R. Farrar, Michael Unger, M. Unger +4 · 3 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #astro-ph.HE

paper · pdf · doi:10.48550/arxiv.1512.00484

Contribution to ICRC 2015. Full exposition (Unger, Farrar and Anchordoqui, accepted for Phys. Rev. D) can be found in arXiv:1505.02153

arxiv created 2015/12/01 · arxiv updated 2015/12/03

Abstract

The sharp change in slope of the ultra-high energy cosmic ray (UHECR) spectrum around 10^18.6 eV (the ankle), combined with evidence of a light but extragalactic component near and below the ankle which evolves to intermediate composition above, has proved exceedingly challenging to understand theoretically. We show that for a range of source conditions, photo-disintegration of ultra-high energy nuclei in the region surrounding a UHECR accelerator naturally accounts for the observed spectrum and composition of the entire extragalactic component, which dominates above about 10^17.5 eV. The mechanism has a clear signature in the spectrum and flavors of neutrinos.

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