Large-Angular-Scale Clustering as a Clue to the Source of UHECRs

TL;DR

This paper proposes that analyzing large-scale clustering of ultra-high energy cosmic rays (UHECRs) can reveal their sources, distinguishing between galaxy clusters, ordinary galaxies, or uncorrelated origins, regardless of deflection or measurement errors.

Contribution

It introduces a method to identify UHECR sources based on their clustering properties related to the mass of host objects, independent of arrival direction uncertainties.

Findings

Clustering strength varies with source mass, enabling source identification.

Future UHECR data can differentiate between galaxy clusters and galaxies as sources.

Clustering analysis remains effective despite magnetic deflections or measurement errors.

Abstract

We show that future Ultra-High Energy Cosmic Ray samples should be able to distinguish whether the sources of UHECRs are hosted by galaxy clusters or ordinary galaxies, or whether the sources are uncorrelated with the large-scale structure of the universe. Moreover, this is true independently of arrival direction uncertainty due to magnetic deflection or measurement error. The reason for this is the simple property that the strength of large-scale clustering for extragalactic sources depends on their mass, with more massive objects, such as galaxy clusters, clustering more strongly than lower mass objects, such as ordinary galaxies.