New constraints on the origin of medium-energy neutrinos observed by IceCube

The recent IceCube publication claims the observation of cosmic neutrinos with energies down to ∼10 TeV, reinforcing the growing evidence that the neutrino flux in the 10-100 TeV range is unexpectedly large. Any conceivable source of these neutrinos must also produce a γ-ray flux which degrades in energy en route to the Earth and contributes to the extragalactic γ-ray background measured by the Fermi satellite. In a quantitative multimessenger analysis, featuring minimalistic assumptions, we find a ≳3σ tension in the data, reaching ∼5σ for cosmic neutrinos extended down to ∼1 TeV, interpreted as evidence for a population of hidden cosmic-ray accelerators.