Magnetically Induced Anisotropies in the Arrival Directions of Ultra-high-energy Cosmic Rays from Nearby Radio Galaxies

TL;DR

This paper uses detailed simulations to study how structured extragalactic magnetic fields influence the arrival directions of ultra-high-energy cosmic rays from nearby radio galaxies, revealing anisotropies and source contributions.

Contribution

It demonstrates the significant impact of structured EGMF on cosmic ray arrival directions and links specific nearby sources to observed anisotropies.

Findings

EGMF structure dominates arrival direction patterns

Virgo A shows no contribution to observed hotspots

Centaurus A, Virgo A, Fornax A contribute to anisotropies

Abstract

Detailed simulations of the arrival directions of ultra-high energy cosmic rays are performed under the assumption of strong and structured extragalactic magnetic field (EGMF) models. Particles leaving Centaurus A, Virgo A, and Fornax A are propagated to Earth, and the simulated anisotropic signal is compared to the dipole and hotspots published by the Pierre Auger and Telescope Array Collaborations. The dominance of the EGMF structure on the arrival directions of events generated in local sources is shown. The absence of events from the Virgo A direction is related to the strong deviation caused by the EGMF. Evidence that these three sources contribute to an excess of events in the direction of the three detected hotspots is presented. Under the EGMF considered here, M82 is shown to have no contribution to the hotspot measured by the Telescope Array Observatory.