If the high-energy (TeV-PeV) neutrinos discovered by IceCube are made via proton-photon interactions in astrophysical sources, their energy spectrum may have a bump-like feature at a characteristic energy. We search for such a feature in present-day IceCube High-Energy Starting Events (HESE), on top of a power-law spectrum expected from alternative production via proton-proton interactions, and make forecasts using the expected exposure of upcoming neutrino telescopes.
We find no significant evidence of bumps in 7.5 years of HESE data, but a bump centered at ~1 PeV is only marginally disfavored. If the true flux does contain such a bump it could be discovered by 2027 using the combined exposure of IceCube, Baikal-GVD, and KM3NeT:
For more information, including interpreting limits on bumps as limits on the properties of the neutrino source population, see
Bump-hunting in the diffuse flux of high-energy cosmic neutrinos
Damiano F. G. Fiorillo, Mauricio Bustamante