Sub-PeV Neutrinos from TeV Unidentified Sources in the Galaxy

TL;DR

This paper investigates whether some of the Sub-PeV neutrinos detected by IceCube originate from Galactic TeV Unidentified sources, modeling them as hypernova remnants and analyzing their potential contribution to the observed neutrino flux.

Contribution

It proposes a novel scenario linking TeV UnID sources to Sub-PeV neutrinos and provides a model predicting their flux and spatial distribution consistent with observations.

Findings

A minority (<~2) of the observed neutrinos may originate from TeV UnID sources.

Most neutrinos (~75-95%) are consistent with an isotropic background.

Predicted neutrino excesses should align with the Galactic plane and Cygnus region.

Abstract

The IceCube collaboration discovery of 28 high-energy neutrinos over the energy range 30 TeV <~ E_nu <~ 1 PeV, a 4.3-sigma excess over expected backgrounds, represents the first high-confidence detection of cosmic neutrinos at these energies. In light of this discovery, we explore the possibility that some of the Sub-PeV cosmic neutrinos might originate in our Galaxy's TeV unidentified (TeV UnID) sources. While typically resolved at TeV energies, these sources lack prominent radio or X-ray counterparts, and so have been considered promising sites for hadron acceleration within our Galaxy. Modeling the TeV UnID sources as Galactic hypernova remnants, we predict Sub-PeV neutrino fluxes and spectra consistent with their contributing a minority of n_nu <~ 2 of the observed events. This is consistent with our analysis of the spatial distribution of the Sub-PeV neutrinos and TeV UnID sources, which finds that a best-fit of one, and maximum of 3.8 (at 90%-confidence), of the ~16 non-atmospheric Sub-PeV neutrinos may originate in TeV UnID sources, with the remaining 75% to 95% of events being drawn from an isotropic background. If our scenario is correct, we expect excess Sub-PeV neutrinos to accumulate along the Galactic plane, within |l| <~ 30 deg of the Galactic center and in the Cygnus region, as observations by IceCube and other high-energy neutrino facilities go forward. Our scenario also has implications for radio, X-ray, and TeV observations of the TeV UnID sources.