IceCube's convex all-sky neutrino spectrum consistent with the magnetically powered corona scenario for active galactic nuclei

TL;DR

This paper shows that the all-sky neutrino spectrum observed by IceCube aligns with the magnetically powered corona model for active galactic nuclei, especially NGC 1068, and discusses implications for multimessenger astrophysics.

Contribution

It demonstrates the consistency of the IceCube neutrino spectrum with the corona scenario in AGNs and assesses the contribution of sources like NGC 1068 to the neutrino flux.

Findings

The neutrino spectrum exhibits a bend around 3-30 TeV.

Models can explain NGC 1068's neutrino emission within uncertainties.

Nuclear activity variations influence predicted neutrino fluxes.

Abstract

High-energy multimessenger background analyses over the past decade have provided evidence for a population of hidden neutrino sources that are opaque to GeV-TeV gamma rays, a picture bolstered by recent observations of the nearby active galaxy NGC 1068. The coronal regions in the hearts of active galactic nuclei (AGNs) have been proposed as the most promising sites for such hidden nonthermal particle production, and NGC 1068 is expected to be the most neutrino-active galaxy for IceCube. We demonstrate that the latest all-sky neutrino spectrum, exhibiting a spectral bend around 3-30 TeV, is consistent with predictions of the magnetically powered corona scenario, and the models for the all-sky neutrino flux can simultaneously explain the multimessenger data from NGC 1068 within observational and modeling uncertainties. We further show, in a largely model-independent way, that the contribution from NGC 1068-like sources does not overshoot the observed medium-energy neutrino flux. Finally, we highlight the key role of the Eddington ratio, which can drive substantial variations in the predicted neutrino fluxes of nearby AGNs, and we encourage systematic multimessenger searches for the neutrino-brightest AGNs.