Bump-hunting in the diffuse flux of high-energy cosmic neutrinos

TL;DR

This paper searches for a characteristic bump in the diffuse high-energy neutrino flux to identify astrophysical sources, finding no current evidence but forecasting future detection potential with larger datasets.

Contribution

It introduces a flexible search method for bump-like features in the neutrino flux and constrains source models using 7.5 years of IceCube data, with promising future prospects.

Findings

No evidence of bump-like features in current data.

Constraints on photohadronic neutrino source populations.

Future data may enable detection or stronger constraints.

Abstract

The origin of the bulk of the high-energy astrophysical neutrinos seen by IceCube, with TeV--PeV energies, is unknown. If they are made in photohadronic, i.e., proton-photon, interactions in astrophysical sources, this may manifest as a bump-like feature in their diffuse flux, centered around a characteristic energy. We search for evidence of this feature, allowing for variety in its shape and size, in 7.5 years of High-Energy Starting Events (HESE) collected by the IceCube neutrino telescope, and make forecasts using larger data samples from upcoming neutrino telescopes. Present-day data reveals no evidence of bump-like features, which allows us to constrain candidate populations of photohadronic neutrino sources. Near-future forecasts show promising potential for stringent constraints or decisive discovery of bump-like features. Our results provide new insight into the origins of high-energy astrophysical neutrinos, complementing those from point-source searches.