Constraints on the neutrino emission from the Galactic Ridge with the ANTARES telescope

TL;DR

This study uses ANTARES data to search for neutrino emissions from the Galactic Ridge, setting upper limits that challenge some models and exclude certain flux extrapolations, thus constraining the origin of IceCube events.

Contribution

It provides the first dedicated search for extended neutrino flux from the Galactic Ridge with ANTARES, testing cosmic ray models and constraining neutrino fluxes.

Findings

No excess neutrino events detected from the Galactic Ridge.

Upper limits set on neutrino fluxes for various spectral indices.

Excludes simple power-law extrapolation of Fermi-LAT flux at 90% confidence.

Abstract

Compelling evidence for the existence of astrophysical neutrinos has been reported by the IceCube collaboration. Some features of the energy and declination distributions of IceCube events hint at a North/South asymmetry of the neutrino flux. This could be due to the presence of the bulk of our Galaxy in the Southern hemisphere. The ANTARES neutrino telescope, located in the Mediterranean Sea, has been taking data since 2007. It offers the best sensitivity to muon neutrinos produced by galactic cosmic ray interactions in this region of the sky. In this letter a search for an extended neutrino flux from the Galactic Ridge region is presented. Different models of neutrino production by cosmic ray propagation are tested. No excess of events is observed and upper limits for different neutrino flux spectral indices are set. This constrains the number of IceCube events possibly originating from the Galactic Ridge. A simple power-law extrapolation of the Fermi-LAT flux to associated IceCube High Energy Starting Events is excluded at 90% confidence level.