Angular correlation of cosmic neutrinos with ultrahigh-energy cosmic rays and implications for their sources

Abstract

Cosmic neutrino events detected by the IceCube Neutrino Observatory with energy $\gtrsim 30$ TeV have poor angular resolutions to reveal their origin. Ultrahigh-energy cosmic rays (UHECRs), with better angular resolutions at $>60$ EeV energies, can be used to check if the same astrophysical sources are responsible for producing both neutrinos and UHECRs. We test this hypothesis, with statistical methods which emphasize invariant quantities, by using data from the Pierre Auger Observatory, Telescope Array and past cosmic-ray experiments. We find that the arrival directions of the cosmic neutrinos are correlated with $\ge 100$ EeV UHECR arrival directions at confidence level $\approx 93\%$. The strength of the correlation decreases with decreasing UHECR energy and no correlation exists at energy $\sim 60$ EeV. A search in astrophysical databases within $3^{\circ }$ of the arrival directions of UHECRs with energy $\ge 100$ EeV, that are correlated with the IceCube cosmic neutrinos, resulted in 18 sources from the Swift-BAT X-ray catalog with redshift $z\le 0.06$. We also found 3 objects in the Kühr catalog of radio sources using the same criteria. The sources are dominantly Seyfert galaxies with Cygnus A being the most prominent member. We calculate the required neutrino and UHECR fluxes to produce the observed correlated events, and estimate the corresponding neutrino luminosity (25 TeV-2.2 PeV) and cosmic-ray luminosity (500 TeV-180 EeV), assuming the sources are the ones we found in the Swift-BAT and Kühr catalogs. We compare these luminosities with the X-ray luminosity of the corresponding sources and discuss possibilities of accelerating protons to $\gtrsim 100$ EeV and produce neutrinos in these sources.

23 pages, 8 figures and 5 tables. Minor changes, improved presentation, added a new figure (Fig.4). Accepted for publication in JCAP

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Cited by in corpus (15)

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• Grand Unified Neutrino Spectrum at Earth: Sources and Spectral Components
• Analysis of the 4-year IceCube high-energy starting events
• 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
• Boosted Dark Matter and its implications for the features in IceCube HESE data
• Do high energy astrophysical neutrinos trace star formation?
• Angular correlation between IceCube high-energy starting events and starburst sources
• Cosmogenic gamma-ray and neutrino fluxes from blazars associated with IceCube events
• How far are the sources of IceCube neutrinos? Constraints from the diffuse TeV gamma-ray background
• Ultra-High Energy Neutrino Afterglows of nearby Long Duration Gamma-Ray Bursts
• Searches for correlation between UHECR events and high-energy gamma-ray Fermi-LAT data
• Blazar origin of some IceCube events
• Seeking Neutrino Emission from AGN through Temporal and Spatial Cross Correlation
• Searching for a Galactic component in the IceCube track-like neutrino events