UHECR Clustering: Lightest Nuclei from Local Sheet Galaxies

TL;DR

This paper proposes that lightest nuclei from nearby galaxies and local sources explain observed UHECR clustering, anisotropy, and composition changes, linking cosmic rays to local extragalactic and galactic sources.

Contribution

It introduces a model where lightest nuclei from local sources account for UHECR clustering and composition, and explores neutrino scattering as an explanation for highest energy events.

Findings

UHECR clustering correlates with local galaxies and AGN within a few Mpc.

Light nuclei from local sources can explain observed anisotropy and composition.

Neutrino scattering models may explain the highest energy UHECR events.

Abstract

The ultra-high-energy cosmic ray (UHECR) puzzle is reviewed under the hints of a few basic results: clustering, anisotropy, asymmetry, bending, and composition changes with energies. We show how the lightest UHECR nuclei from the nearest AGN or Star-Burst sources, located inside a few Mpc Local Sheets, may explain, at best, the observed clustering of Hot Spots at tens EeV energy. Among the possible local extragalactic candidate sources, we derived the main contribution of very few galactic sources. These are located in the Local Sheet plane within a distance of a few Mpc, ejecting UHECR at a few tens of EeV energy. UHECR also shine at lower energies of several EeV, partially feeding the Auger dipole by LMC and possibly a few nearer galactic sources. For the very recent highest energy UHECR event, if a nucleon, it may be explained by a model based on the scattering of UHE ZeV neutrinos on low-mass relic neutrinos. Such scatterings are capable of correlating, via Z boson resonance, the most distant cosmic sources above the GZK bound with such an enigmatic UHECR event. Otherwise, these extreme events, if made by the heaviest composition, could originate from the largest bending trajectory of heaviest nuclei or from nearby sources, even galactic ones. In summary, the present lightest to heavy nuclei model UHECR from the Local Sheet could successfully correlate UHECR clustering with the nearest galaxies and AGN. Heavy UHECR may shine by being widely deflected from the Local Sheet or from past galactic, GRB, or SGR explosive ejection.