Neutrino signal from Cygnus region of the Milky Way

TL;DR

This paper uses ten years of IceCube neutrino data to provide evidence of hadronic processes in the Cygnus region, supporting the idea that gamma-ray emissions there are produced by cosmic ray interactions.

Contribution

It demonstrates the first significant neutrino excess from the Cygnus region, confirming hadronic origin of gamma-ray emission using neutrino observations.

Findings

3-sigma neutrino excess from Cygnus Cocoon

Neutrino flux comparable to gamma-ray flux in multi-TeV range

Supports hadronic origin of gamma-ray emission in Cygnus region

Abstract

Interactions of cosmic ray protons and nuclei in their sources and in the interstellar medium produce "hadronic" gamma-ray emission. Gamma-rays can also be of "leptonic" origin, i.e. originating from high-energy electrons accelerated together with protons. It is difficult to distinguish between hadronic and leptonic emission mechanisms based on gamma-ray data alone. This can be done via detection of neutrinos, because only hadronic processes lead to neutrino production. We use publicly available ten-year IceCube neutrino telescope dataset to demonstrate the hadronic nature of high-energy emission from the direction of Cygnus region of the Milky Way. We find a 3-sigma excess of neutrino events from an extended Cygnus Cocoon, with the flux comparable to the flux of gamma-rays in the multi-TeV energy range seen by HAWC and LHAASO telescopes.