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We report in detail on searches for eV-scale sterile neutrinos, in the context of a 3 þ 1 model, using eight years of data from the IceCube Neutrino Telescope. By analyzing the reconstructed energies and zenith angles of 305,735 atmospheric ν μ andν μ events we construct confidence intervals in two analysis spaces: sin 2 ð2θ 24 Þ vs Δm 2 41 under the conservative assumption θ 34 ¼ 0; and sin 2 ð2θ 24 Þ vs sin 2 ð2θ 34 Þ given sufficiently large Δm 2 41 that fast oscillation features are unresolvable. Detailed discussions of the event selection, systematic uncertainties, and fitting procedures are presented. No strong evidence for sterile neutrinos is found, and the best-fit likelihood is consistent with the no sterile neutrino hypothesis with a p value of 8% in the first analysis space and 19% in the second.

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

The results of a 3 þ 1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energyzenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100 eV 2. The best-fit point is found to be at sin 2 ð2θ 24 Þ ¼ 0.10 and Δm 2 41 ¼ 4.5 eV 2 , which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.