The IceCube neutrino telescope at the South Pole has measured the atmospheric muon neutrino spectrum as a function of zenith angle and energy in the approximate 320 GeV to 20 TeV range, to search for the oscillation signatures of light sterile neutrinos. No evidence for anomalous $\nu_\mu$ or $\bar{\nu}_\mu$ disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data. New exclusion limits are placed on the parameter space of the 3+1 model, in which muon antineutrinos would experience a strong MSW-resonant oscillation. The exclusion limits extend to $\mathrm{sin}^2 2\theta_{24} \leq$ 0.02 at $\Delta m^2 \sim$ 0.3 $\mathrm{eV}^2$ at the 90\% confidence level. The allowed region from global analysis of appearance experiments, including LSND and MiniBooNE, is excluded at approximately the 99\% confidence level for the global best fit value of $|$U$_{e4}|^2$.Comment: 10 pages, 5 figure

We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10-60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (Δm 2 41 ∼ 1 eV 2 ) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of jU μ4 j 2 < 0.11 and jU τ4 j 2 < 0.15 (90% C.L.) for the sterile neutrino mass splitting Δm 2 41 ¼ 1.0 eV 2 .

We report constraints on the sources of ultra-high-energy cosmic rays (UHECRs) above 10 9 GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high energy neutrino-induced events which have deposited energies from 5 × 10 5 GeV to above 10 11 GeV. Two neutrino-induced events with an estimated deposited energy of (2.6 ± 0.3) × 10 6 GeV, the highest neutrino energy observed so far, and (7.7 ± 2.0) × 10 5 GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the non-observation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources 3 having cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultra-high-energy neutrino flux models are the most stringent to date. Introduction -The sources of ultra-high-energy cosmic rays (UHECRs; cosmic-ray energy E CR 10 18 eV) remain unidentified [1]. The majority of the candidate objects are extra-Galactic, such as Active Galactic Nuclei (AGN) [2-6] , γ-ray bursts [7][8][9][10][11][12][13], and starburst galaxies [14][15][16][17][18][19]. UHECR interactions with ambient photons and matter at sources generate astrophysical neutrinos with 5% of the parent UHECR energy, on average [20][21][22]. Thus, a substantial fraction of these Extremely High-Energy (EHE) astrophysical neutrinos is expected to have an energy above 10 7 GeV. Moreover, neutrinos with energies above ∼107 GeV are expected to be produced in the interactions between the highest-energy cosmic rays and background photons in the universe [23]. In the following we refer to the neutrinos produced in these interactions as cosmogenic neutrinos [24]. These astrophysical and cosmogenic EHE neutrinos can constitute key messengers identifying currently unknown cosmic accelerators, possibly in the distant universe, because their propagation is not influenced by background photon or magnetic fields.

Abstract. TUS (Tracking Ultraviolet Set-up), the first orbital detector of extreme energy cosmic rays (EECRs), those with energies above 50 EeV, was launched into orbit on April 28, 2016, as a part of the Lomonosov satellite scientific payload. The main aim of the mission is to test a technique of registering fluorescent and Cherenkov radiation of extensive air showers generated by EECRs in the atmosphere with a space telescope. We present preliminary results of its operation in a mode dedicated to registering extensive air showers in the period from August 16, 2016, to November 4, 2016. No EECRs have been conclusively identified in the data yet, but the diversity of ultraviolet emission in the atmosphere was found to be unexpectedly rich. We discuss typical examples of data obtained with TUS and their possible origin. The data is important for obtaining more accurate estimates of the nocturnal ultraviolet glow of the atmosphere, necessary for successful development of more advanced orbital EECR detectors including those of the KLYPVE (K-EUSO) and JEM-EUSO missions.

The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of recent findings from the analysis of IceCube data, and their implications to our understanding of cosmic rays.