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

2 Pith papers cite this work. Polarity classification is still indexing.

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abstract

We propose that ultra-high-energy (UHE) cosmic rays (CRs) above $10^{18}$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 $\lesssim 10^{17}$eV that penetrate the jet sideways receive a "one-shot'" boost of a factor of $\sim\Gamma^2$ in energy, where $\Gamma$ 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 $\Gamma\gtrsim 30$ may accelerate UHECRs up to more than $10^{20}$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 $10^{18}$eV and increasingly heavy at higher energies, in agreement with recent observations made at the Pierre Auger Observatory.

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astro-ph.HE 2

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2026 1 2024 1

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UNVERDICTED 2

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representative citing papers

Ultraheavy Ultrahigh-Energy Cosmic Rays

astro-ph.HE · 2024-05-27 · unverdicted · novelty 7.0

Ultraheavy nuclei have longer energy loss lengths at ≲300 EeV than lighter nuclei, allowing them to explain UHECRs above 100 EeV from sources like collapsars and neutron star mergers while predicting distinct shower maxima.

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