Propagation of ultra high energy cosmic rays

TL;DR

This paper reviews how ultra high energy cosmic rays lose energy during propagation, their interactions with cosmic photon fields, and how recent experimental results align with theoretical predictions.

Contribution

It provides an overview of energy loss mechanisms and discusses recent experimental findings in the context of propagation models for ultra high energy cosmic rays.

Findings

Energy loss processes affect cosmic ray spectra

Gamma rays and neutrinos carry source information

Recent HiRes and Auger results support propagation models

Abstract

We briefly describe the energy loss processes of ultrahigh energy protons, heavier nuclei and gamma rays in interactions with the universal photon fields of the Universe. We then discuss the modification of the accelerated cosmic ray energy spectrum in propagation by the energy loss processes and the charged cosmic ray scattering in the extragalactic magnetic fields. The energy lost by the ultrahigh energy cosmic rays goes into gamma rays and neutrinos that carry additional information about the sources of highest energy particles. The new experimental results of the HiRes and the Auger collaborations are discussed in view of the predictions from propagation calculations.