Ultra-High-Energy Cosmic Rays and Neutrinos from Relativistic Jets of Active Galactic Nuclei

TL;DR

This paper develops a comprehensive simulation-based model of ultra-high-energy cosmic rays and neutrinos originating from relativistic jets of active galactic nuclei, aligning well with current observational data.

Contribution

It introduces a realistic 3D MHD simulation framework that includes sub-grid turbulence modeling and analyzes the acceleration, composition, and neutrino production in AGN jets.

Findings

Results match observed UHECR spectra and composition.

Model explains UHECR anisotropy and energy distribution.

Predicted neutrino fluxes are consistent with IceCube observations.

Abstract

In Mbarek & Caprioli (2019), we laid the groundwork for studying the espresso paradigm Caprioli (2015), a reacceleration mechanism to boost galactic CRs to UHECR levels. Our bottom-up approach uses realistic 3D MHD simulations of relativistic AGN jets and accounts for all of the crucial ingredients of a universal acceleration theory: injection, acceleration, and escape in realistic environments. Our results are consistent with the main features of UHECR spectra, i.e., power-law slopes, chemical composition, and anisotropy. In Mbarek & Caprioli (2021), we refine our model by including sub-grid particle scattering to model small-scale magnetic turbulence that cannot be resolved by MHD simulations, constraining for the first time one crucial but hard-to-model ingredient, and allowing us to establish the relative importance of espresso and stochastic shear acceleration in relativistic jets. Our framework also enables us to analyze high-energy neutrinos produced from our accelerated UHECRs considering the effects of external photon fields, and to incorporate nucleus photodisintegration. The spectra we obtain are consistent with the picture drawn by observations with Auger, Telescope Array, and IceCube observatory.