paper

"Espresso" Acceleration of Ultra-high-energy Cosmic Rays

arXiv:1505.06739 · doi:10.1088/2041-8205/811/2/L38

Abstract

We propose that ultra-high-energy (UHE) cosmic rays (CRs) above eV are produced in relativistic jets of powerful active galactic nuclei via an original mechanism, which we dub "espresso" acceleration: "seed" galactic CRs with energies eV that penetrate the jet sideways receive a "one-shot'" boost of a factor of in energy, where is the Lorentz factor of the relativistic flow. For typical jet parameters, a few percent of the CRs in the host galaxy can undergo this process, and powerful blazars with may accelerate UHECRs up to more than eV. The chemical composition of espresso-accelerated UHECRs is determined by that at the Galactic CR knee and is expected to be proton-dominated at eV and increasingly heavy at higher energies, in agreement with recent observations made at the Pierre Auger Observatory.

5 pages, 2 figures. Fixed one typo in a footnote

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