Extragalactic propagation of ultrahigh energy cosmic-rays

TL;DR

This review discusses how ultrahigh energy cosmic rays propagate through extragalactic space, focusing on energy loss processes, magnetic field effects, and implications for their origins and composition.

Contribution

It provides a comprehensive overview of the physical processes affecting UHECRs during extragalactic propagation, including recent composition analysis and multi-messenger implications.

Findings

Energy loss processes significantly shape UHECR spectrum.

Extragalactic magnetic fields influence cosmic-ray trajectories.

Secondary neutrinos and photons offer constraints on UHECR sources.

Abstract

In this paper we review the extragalactic propagation of ultrahigh energy cosmic-rays (UHECR). We present the different energy loss processes of protons and nuclei, and their expected influence on energy evolution of the UHECR spectrum and composition. We discuss the possible implications of the recent composition analyses provided by the Pierre Auger Observatory. The influence of extragalactic magnetic fields and possible departures from the rectilinear case are also mentioned as well as the production of secondary cosmogenic neutrinos and photons and the constraints their observation would imply for the UHECRs origin. Finally, we conclude by briefly discussing the relevance of a multi messenger approach for solving the mystery of UHECRs.