Estimatingthe Contribution of Galactic Neutrino Sources

TL;DR

This study estimates the source contribution to the Galactic neutrino flux using simulated gamma-ray source populations, finding it consistent with observations and suggesting the propagation component dominates.

Contribution

It introduces a bracketing approach to constrain the Galactic neutrino flux contribution from sources based on gamma-ray and supernova remnant simulations.

Findings

The source contribution range is less than an order of magnitude.

The flux range aligns with the Galactic neutrino flux from cosmic-ray interactions.

Propagation dominates the observed neutrino flux, with minimal room for additional source contributions.

Abstract

The Milky Way hosts astrophysical accelerators capable of producing high-energy cosmic rays. These cosmic rays can interact with the interstellar medium (ISM) across the Galaxy to produce neutrinos and gamma rays (propagation component), while their interactions with ambient material at their acceleration sites, such as supernova remnants, can give rise to the source component of the gamma-ray and neutrino flux. In this paper, we estimate the source component of the Galactic neutrino flux using simulated populations of Galactic gamma-ray sources. We compare our results with observations from neutrino experiments in the energy range of 1-30 TeV. Using simulated populations of Galactic TeV gamma-ray sources, we exploit the correlation between gamma rays and neutrinos and introduce a bracketing approach to constrain the range for the source contribution of the Galactic neutrino flux. For the upper limit, we used a simulation describing the entity of Galactic gamma-ray sources, whereas the lower limit was estimated using the hadronic component of the Galactic supernova remnant population. Our results show that the difference between this maximum and minimum is less than an order of magnitude and the flux range is comparable to the Galactic neutrino flux from the cosmic-ray interaction with the ISM. The results agree with the observed signals from IceCube and ANTARES and suggest that the propagation component, combined with the minimum source contribution predicted by the supernova-remnant model, approaches the observed neutrino flux, leaving little room for significant enhancements of the emission originating from propagating cosmic rays.