The UHECR-FR0 Radio Galaxy Connection: A Multi-Messenger Study of Energy Spectra/Composition Emission and Intergalactic Magnetic Field Propagation

TL;DR

This paper explores low luminosity FR0 radio galaxies as potential sources of ultra-high energy cosmic rays, using simulations to compare their emission spectra and composition with observational data, considering intergalactic magnetic fields and multi-messenger signals.

Contribution

It introduces detailed simulations of FR0 galaxies as UHECR sources, incorporating magnetic fields and multi-messenger predictions, and compares results with Pierre Auger Observatory data.

Findings

FR0 galaxies could significantly contribute to UHECR energy density.

Simulated spectra and composition align with Auger observations under certain conditions.

Predicted secondary photon and neutrino fluxes inform multi-messenger astrophysics.

Abstract

This study investigates low luminosity Fanaroff-Riley Type 0 (FR0) radio galaxies as a potentially significant source of ultra-high energy cosmic rays (UHECRs). Due to their much higher prevalence in the local universe compared to more powerful radio galaxies (about five times more than FR-1s), FR0s may provide a substantial fraction of the total UHECR energy density. To determine the nucleon composition and energy spectrum of UHECRs emitted by FR0 sources, simulation results from CRPropa3 are fit to Pierre Auger Observatory data. The resulting emission spectral indices, rigidity cutoffs, and nucleon fractions are compared to recent Auger results. The FR0 simulations include the approximately isotropic distribution of FR0 galaxies and various intergalactic magnetic field configurations (including random and structured fields) and predict the fluxes of secondary photons and neutrinos produced during UHECR propagation through cosmic photon backgrounds. This comprehensive simulation allows for investigating the properties of the FR0 sources using observational multi-messenger data.