High-Energy Neutrino Emission from Espresso-Reaccelerated Ions in Jets of Active Galactic Nuclei

TL;DR

This paper models ultra-high energy cosmic ray and neutrino production in AGN jets using detailed simulations, finding heavy nuclei may dominate cosmic rays and neutrino fluxes could be significant, especially from nearby radio galaxies.

Contribution

It introduces a comprehensive simulation approach combining 3D MHD jet models with particle propagation to estimate UHECR and neutrino fluxes from AGNs, highlighting the espresso acceleration mechanism's role.

Findings

UHECRs may be heavy nuclei at highest energies.

Neutrino fluxes from AGN jets could dominate cosmogenic neutrinos.

Nearby radio galaxies are promising neutrino sources.

Abstract

We present a bottom-up calculation of the flux of ultra-high energy cosmic rays (UHECRs) and high-energy neutrinos produced by powerful jets of active galactic nuclei (AGNs). By propagating test particles in 3D relativistic magnetohydrodynamic jet simulations, including a Monte Carlo treatment of sub-grid pitch-angle scattering and attenuation losses due to realistic photon fields, we study the spectrum and composition of the accelerated UHECRs and estimate the amount of neutrinos produced in such sources. We find that UHECRs may not be significantly affected by photodisintegration in AGN jets where the espresso mechanism efficiently accelerates particles, consistent with Auger's results that favor a heavy composition at the highest energies. Moreover, we present estimates and upper bounds for the flux of high-energy neutrinos expected from AGN jets. In particular, we find that: i) source neutrinos may account for a sizable fraction, or even dominate, the expected flux of cosmogenic neutrinos; ii) neutrinos from the beta-decay of secondary neutrons produced in nucleus photodisintegration end up in the TeV-PeV band observed by IceCube, but can hardly account for the observed flux; iii) UHECRs accelerated via the espresso mechanism lead to nearly isotropic neutrino emission, which suggests that nearby radio galaxies may be more promising as potential sources. We discuss our results in the light of multimessenger astronomy and current/future neutrino experiments.