All-sky search for correlations in the arrival directions of astrophysical neutrino candidates and ultrahigh-energy cosmic rays

High-energy neutrinos, being neutral and weakly interacting particles, are powerful probes of the sites of production and acceleration of cosmic rays. The challenging discovery of cosmic neutrinos by the IceCube Collaboration has moved the field closer to realizing the potential of neutrino astronomy. Meanwhile, ground-based cosmic ray detectors like the Pierre Auger Observatory and the Telescope Array have reached an unprecedented accuracy in the determination of the features of the cosmic rays at the highest energies. We report on a collaborative effort between IceCube, the Pierre Auger Observatory and Telescope Array to identify directional correlations between the arrival directions of the highest-energy cosmic rays from both hemispheres and of the most probable cosmic neutrino events detected by IceCube. We describe the updated results of two independent searches using seven years of IceCube neutrino data and the most energetic cosmic-ray events detected by the Pierre Auger Observatory and the Telescope Array. The directional correlation found between UHECRs and neutrinos is reported with a significance of ∼2σ.SCOPUS: cp.pSCOPUS: cp.pinfo:eu-repo/semantics/publishe

Search for a correlation between the UHECRs measured by the pierre auger observatory and the telescope array and the neutrino candidate events from IceCube

We have conducted three searches for correlations between ultra-high energy cosmic rays detected by the Telescope Array and the Pierre Auger Observatory, and high-energy neutrino candidate events from IceCube. Two cross-correlation analyses with UHECRs are done: one with 39 cascades from the IceCube 'high-energy starting events' sample and the other with 16 high-energy 'track events'. The angular separation between the arrival directions of neutrinos and UHECRs is scanned over. The same events are also used in a separate search using a maximum likelihood approach, after the neutrino arrival directions are stacked. To estimate the significance we assume UHECR magnetic deflections to be inversely proportional to their energy, with values 3-, 6- and 9- at 100 EeV to allow for the uncertainties on the magnetic field strength and UHECR charge. A similar analysis is performed on stacked UHECR arrival directions and the IceCube sample of through-going muon track events which were optimized for neutrino point-source searches.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Correlation between the UHECRs measured by the Pierre Auger Observatory and Telescope Array and neutrino candidate events from IceCube

We present the results of three searches for correlations between ultra-high energy cosmic ray events measured by Telescope Array and the Pierre Auger Observatory and high-energy neutrino candidate events from IceCube. Two cross-correlation analyses of ultra-high energy cosmic rays are done: one with 39 "cascades" from the IceCube "high-energy starting events" sample and the other one with 16 high-energy "tracks". The angular separation between the arrival directions of neutrinos and UHECRs is scanned. The same events are also used in a separate search stacking the neutrino arrival directions and using a maximum likelihood approach. We assume that UHECR magnetic deflections are inversely proportional to the energy with values 3, 6 and 9 at 100 EeV to account for the uncertainties in the magnetic field strength and UHECR charge. A similar analysis is performed on stacked UHECR arrival directions and the IceCube 4-year sample of through-going muon-track events that was optimized for neutrino point source searches.SCOPUS: cp.pinfo:eu-repo/semantics/publishe