IceCube and LHAASO data require unresolved Galactic sources for most observed neutrinos

{"Roberts et al. combined IceCube's high-energy neutrino observations from the Galactic Plane with LHAASO's diffuse gamma-ray measurements. They modeled three components: diffuse emission from cosmic-ray interactions in the interstellar medium, unresolved TeV halos, and additional unresolved Galactic neutrino sources. Gamma-ray data fit a mix of diffuse processes and TeV halos, but neutrino emission demanded extra source contributions regardless of assumed transport parameters.","This multimessenger approach directly constrains the origin of high-energy cosmic rays, a puzzle where supernova remnants and other populations compete. Prior IceCube analyses of the Galactic plane already hinted at source dominance, yet lacked joint gamma-ray constraints to break degeneracies in propagation models. The new result quantifies that sources likely produce most of the observed neutrinos, narrowing viable candidates to populations like pulsar wind nebulae or microquasars.","The study highlights how single-messenger data leave source fractions ambiguous. Adding LHAASO gamma rays tightens the allowed parameter space for transport and source spectra. Future analyses incorporating KM3NeT or improved LHAASO sensitivity could test whether specific source classes dominate, moving beyond flux upper limits to population discrimination.","Next steps include cross-checks with HAWC and Tibet AS-gamma data plus refined modeling of TeV halo contributions. Stronger evidence would come from individual source detections or anisotropy measurements that separate diffuse and discrete components."}