“ESPRESSO” ACCELERATION OF ULTRA-HIGH-ENERGY COSMIC RAYS Article Swipe
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· 2015
· Open Access
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· DOI: https://doi.org/10.1088/2041-8205/811/2/l38
· OA: W1793559938
We propose that ultra-high-energy (UHE) cosmic rays (CRs) above $10^{18}$eV\nare produced in relativistic jets of powerful active galactic nuclei via an\noriginal mechanism, which we dub "espresso" acceleration: "seed" galactic CRs\nwith energies $\\lesssim 10^{17}$eV that penetrate the jet sideways receive a\n"one-shot'" boost of a factor of $\\sim\\Gamma^2$ in energy, where $\\Gamma$ is\nthe Lorentz factor of the relativistic flow. For typical jet parameters, a few\npercent of the CRs in the host galaxy can undergo this process, and powerful\nblazars with $\\Gamma\\gtrsim 30$ may accelerate UHECRs up to more than\n$10^{20}$eV. The chemical composition of espresso-accelerated UHECRs is\ndetermined by that at the Galactic CR knee and is expected to be\nproton-dominated at $10^{18}$eV and increasingly heavy at higher energies, in\nagreement with recent observations made at the Pierre Auger Observatory.\n
