Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array

TL;DR

This study investigates potential correlations between high-energy neutrino events detected by IceCube and ultrahigh-energy cosmic rays from Pierre Auger and Telescope Array, finding no significant correlations but highlighting a promising signal in cascade neutrino events.

Contribution

The paper introduces comprehensive correlation analyses between neutrino and cosmic ray data, including new likelihood methods and multiple datasets, to explore potential astrophysical sources.

Findings

No significant correlation detected at the current sensitivity levels.

The lowest p-value was from the correlation between UHECRs and IceCube cascade neutrinos.

Results suggest continued monitoring of the cascade neutrino correlation is warranted.

Abstract

This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.