A Multi-Component Model for the Observed Astrophysical Neutrinos

TL;DR

This paper introduces a comprehensive multi-component model for astrophysical neutrinos, integrating atmospheric, galactic, and extragalactic sources, to explain observed spectral features, anisotropies, and high-energy events.

Contribution

It presents a novel multi-component framework that accounts for various neutrino sources and explains key observational phenomena in high-energy astrophysics.

Findings

The model explains spectral index differences between muon samples.

It accounts for potential anisotropy from Galactic sources.

It interprets the 4.5 PeV muon event as extragalactic photo-hadronic evidence.

Abstract

We propose a multi-component model for the observed diffuse neutrino flux, including the residual atmospheric backgrounds, a Galactic contribution (such as from cosmic ray interactions with gas), an extra-galactic contribution from pp interactions (such as from starburst galaxies) and a hard extragalatic contribution from photo-hadronic interactions at the highest energies (such as from Tidal Disruption Events or Active Galactic Nuclei). We demonstrate that this model can address the key problems of astrophysical neutrino data, such as the different observed spectral indices in the high-energy starting and through-going muon samples, a possible anisotropy due to Galactic events, the non-observation of point sources, and the constraint from the extragalatic diffuse gamma-ray background. Furthermore, the recently observed muon track with a deposited energy of 4.5 PeV might be interpreted as evidence for the extragalactic photo-hadronic contribution. We perform the analysis based on the observed events instead of the unfolded fluxes by computing the probability distributions for the event type and reconstructed neutrino energy. As a consequence, we give the probability to belong to each of these astrophysical components on an event-to-event basis.