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 $\sim 10$ 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 $\gamma$-ray flux which degrades in energy en route to the Earth and contributes to the extragalactic $\gamma$-ray background measured by the Fermi satellite. In a quantitative multimessenger analysis, featuring minimalistic assumptions, we find a $\geq 3\sigma$tensioninthedata,reaching$\sim 5\sigma$ for cosmic neutrinos extended down to $\sim 1$ TeV, interpreted as evidence for a population of hidden cosmic-ray accelerators.