UHECRs from the Radio Lobes of AGNs

TL;DR

This paper presents a first-principles stochastic acceleration mechanism in AGN radio lobes, showing protons can reach ultra-high energies within a million years, influencing the understanding of the high-energy cutoff in cosmic ray spectra.

Contribution

It introduces a novel stochastic acceleration model for particles in AGN radio lobes based on first principles, explaining how ultra-high-energy cosmic rays can be produced.

Findings

Protons can reach energies of ~10^20 eV in about 10^6 years.

The high-energy cutoff may be due to the acceleration process itself, not just propagation effects.

The mechanism revisits the origin of ultra-high-energy cosmic rays in AGNs.

Abstract

We report a stochastic mechanism of particle acceleration from first principles in an environment having properties like those of Radio Lobes in AGNs. We show that energies $\sim 10^{20}$ eV are reached in $\sim 10^6$ years for protons. Our results reopen the question regarding the nature of the high-energy cutoff in the observed spectrum: whether it is due solely to propagation effects, or whether it is also affected by the maximum energy permitted by the acceleration process itself.