Where are the Ultra High Energy Cosmic Ray (UHECR) originated?

TL;DR

This paper reviews recent findings on the composition, distribution, and potential sources of ultra high energy cosmic rays, suggesting nearby extragalactic sources and exploring the role of relic neutrinos in explaining distant clustering events.

Contribution

It summarizes current observational evidence and discusses possible astrophysical and particle physics explanations for the origins of UHECRs, including new hypotheses involving relic neutrinos.

Findings

UHECRs are mostly composed of light nuclei.

Most UHECRs originate from nearby extragalactic sources like CenA, NG 253, M82.

Relic neutrinos may play a role in distant UHECR clustering events.

Abstract

We consider the recent results on UHECR (Ultra High Energy Cosmic Ray) composition and their distribution in the sky from ten EeV energy (the dipole anisotropy) up to the highest UHECR energies and their clustering maps: UHECR have been found mostly made by light and lightest nuclei. We summarized the arguments that favor a few localized nearby extragalactic sources for most UHECR as CenA, NG 253, M82. We comment also on the possible partial role of a few remarkable galactic UHECR sources. Finally we revive the eventual role of a relic neutrino eV mass in dark hot halo (hit by ZeV neutrinos) to explain the new UHECR clustering events centered around a very far cosmic AGN sources as 3C 454.