Constraints on Galactic Neutrino Emission with Seven Years of IceCube Data

Abstract

The origins of high-energy astrophysical neutrinos remain a mystery despite extensive searches for their sources. We present constraints from seven years of IceCube Neutrino Observatory muon data on the neutrino flux coming from the Galactic plane. This flux is expected from cosmic-ray interactions with the interstellar medium or near localized sources. Two methods were developed to test for a spatially extended flux from the entire plane, both of which are maximum likelihood fits but with different signal and background modeling techniques. We consider three templates for Galactic neutrino emission based primarily on gamma-ray observations and models that cover a wide range of possibilities. Based on these templates and in the benchmark case of an unbroken E − 2.5 power-law energy spectrum, we set 90% confidence level upper limits, constraining the possible Galactic contribution to the diffuse neutrino flux to be relatively small, less than 14% of the flux reported in Aartsen et al. above 1 TeV. A stacking method is also used to test catalogs of known high-energy Galactic gamma-ray sources.

Probing strong dynamics with cosmic neutrinos

“…More concretely, we implemented the standard statistical analysis, using two uncorrelated observables (up-and down-going events), to determine the best fit model parameters (flux and cross section) and the fluctuations around the favored values. The hypotheses of the model being tested are: (i) an isotropic neutrino flux and (ii) flavor ratios democratically distributed on Earth, both consistent with IceCube data [30][31][32][33]35]. Current results from IceCube already provide interesting constraints on the flux cross-section parameter space.…”

High-energy cosmic ray production in X-ray binary jets

“…The current upper limits on the Figure 5. The predicted diffuse Galactic neutrino spectrum from SNR-CRs and XRB-CRs with joint upper limits from ANTARES and IceCube (Aartsen et al 2017) using the DRAGON code. Specifically, we note that breaks in the spectra are predicted in the total spectrum at model-dependent sensitivities even with very conservative maximum energy cut-offs.…”

Angular power spectrum analysis on current and future high-energy neutrino data

“…Nevertheless, besides XS 0506+056 no other point-source was found, which sets constraints on the contribution of source populations, e.g., gamma-ray bursts [21], core-collapse supernovae [22], active galactic nuclei [23], starburst galaxies [24] and galaxy clusters and groups [25]. Moreover, also a galactic contribution is predicted, which is found to be relatively small and we will thus not consider this in our analysis [26,27].…”