Propagation of ultra-high-energy cosmic rays in the magnetized cosmic web

TL;DR

This paper models the propagation of ultra-high-energy cosmic rays in the magnetized cosmic web to explore their potential origin of the Telescope Array hotspot, focusing on the role of cosmic magnetic fields in clusters and filaments.

Contribution

It introduces a novel model of UHECR propagation through the cosmic web, emphasizing magnetic confinement and escape pathways from galaxy clusters.

Findings

Ratio of particles escaping directly to voids versus filaments

Trajectories of UHE protons in simulated magnetic fields

Feasibility assessment of the model for hotspot origin

Abstract

A high concentration of ultra-high-energy cosmic ray (UHECR) events, called a hotspot, was reported by the Telescope Array (TA) experiment, but its origin still remains unsolved. One of the obstacles is that there is no astronomical object, which could be the source, behind the TA hotpot. In an effort to understand the origin of the TA hotspot, we suggested a model based on the magnetized cosmic web structure. The UHECRs were produced from sources in the Virgo cluster and were initially confined by cluster magnetic fields for a certain period. Next, some of them preferentially escaped to and propagated along filaments. Eventually, they were scattered by filament magnetic fields, and come to us. To examine the model, we followed the propagation trajectories of UHE protons in a simulated universe with clusters, filaments, and voids, by employing a number of models for cosmic magnetic fields. In this study, we present some of the initial results, such as the ratio between the particles directly escaping from the clusters to the voids and particles escaping from the clusters to the filaments. We also discuss the feasibility of our model for the origin of the hotspot by examining the trajectories of the UHE protons.