Multimessenger search for point sources: ultra-high energy cosmic rays and neutrinos

TL;DR

This paper proposes a novel multimessenger approach combining ultra-high energy cosmic rays and neutrinos to identify astrophysical point sources, using a statistical cross-correlation method to detect potential associations.

Contribution

It introduces a new statistical framework for cross-correlating UHECRs and neutrinos, considering magnetic deflections, to improve source identification in high-energy astrophysics.

Findings

Proposed a statistical method for cross-correlation analysis.

Discussed the impact of magnetic deflections on source localization.

Outlined how correlations could confirm hadronic acceleration sources.

Abstract

The origin of ultra-high energy cosmic rays (UHECRs) and neutrinos is still a mystery. Hadronic acceleration theory suggests that they should originate in the same sources (astrophysical or cosmological), together with gamma-rays. While gamma-rays have been linked to astrophysical sources, no point source of UHECRs or neutrinos have been found so far. In this paper, the multimessenger combination of UHECRs and neutrinos as a new approach to the high energy particle point source search is suggested. A statistical method for cross-correlation of UHECR and neutrino data sets is proposed. By obtaining the probability density function of number of neutrino events within chosen angular distance from observed UHECRs, the number of neutrino events in the vicinity of observed UHECRs, necessary to claim a discovery with a chosen significance, can be calculated. Different angular distances (bin sizes) are considered due to the unknown deflection of cosmic rays in galactic and intergalactic magnetic fields. Possible observed correlation of the arrival directions of UHECRs and neutrinos would provide a strong indication of hadronic acceleration theory. Correlation of both types of messengers with the location of certain sets of observed astrophysical objects would indicate sites of acceleration. Any systematic offset in arrival directions between UHECRs and neutrinos may shed more light on magnetic field deflection of cosmic rays.