Publication
Interactions of cosmic-ray protons and nuclei in their sources and in the interstellar medium produce "hadronic" 7-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 7-ray data alone. This can be done via detection of neutrinos, because only hadronic processes lead to neutrino production. We use the publicly available 10 yr IceCube neutrino telescope dataset to demonstrate the hadronic nature of high-energy emission from the direction of the Cygnus region of the Milky Way. We find a 36 excess of neutrino events from an extended Cygnus Cocoon, with the flux comparable to the flux of 7 rays in the multi-TeV energy range seen by HAWC and LHAASO telescopes.