Search for Spatial Correlations of Neutrinos with Ultra-high-energy Cosmic Rays

Abstract

[EN] For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high- energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not de¿ected by magnetic ¿elds. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data are provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above ~50 EeV are provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The ¿rst analysis uses a high-statistics neutrino sample optimized for point- source searches to search for excesses of neutrino clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses have found a signi¿cant excess, and previously reported over¿uctuations are reduced in signi¿cance. Based on these results, we further constrain the neutrino ¿ux spatially correlated with UHECRs.