Could nearby star-forming galaxies light up the point-like neutrino sky?

TL;DR

This study models gamma-ray and neutrino emissions from nearby star-forming galaxies, predicting their detectability as point sources with current and future neutrino telescopes, and emphasizing the importance of joint gamma-ray and neutrino observations.

Contribution

It introduces a physical model linking star-forming activity to high-energy neutrino and gamma-ray emissions, assessing their detectability with upcoming telescopes.

Findings

Potential observability of the Small Magellanic Cloud and Circinus galaxy by KM3NeT/ARCA within 6 years.

Most nearby galaxies are close to the sensitivity thresholds of KM3NeT and IceCube-Gen2.

Joint gamma-ray and neutrino observations can test the star-forming activity as a neutrino source.

Abstract

Star-forming and starburst galaxies, which are well-known cosmic-rays reservoirs, are expected to emit gamma-rays and neutrinos predominantly via hadronic collisions. In this Letter, we analyze the 10-year Fermi-LAT spectral energy distributions of 13 nearby galaxies by means of a physical model which accounts for high-energy proton transport in starburst nuclei and includes the contribution of primary and secondary electrons. In particular, we test the hypothesis that the observed gamma-ray fluxes are mostly due to star-forming activity, in agreement with the available star formation rates coming from IR and UV observations. Through this observation-based approach, we determine the most-likely neutrino counterpart from star-forming and starburst galaxies and quantitatively assess the ability of current and upcoming neutrino telescopes to detect them as point-like sources. Remarkably, we find that the cores of the Small Magellanic Cloud and the Circinus galaxy are potentially observable by KM3NeT/ARCA with 6 years of observation. Moreover, most of the nearby galaxies are likely to be just a factor of a few below the KM3NeT and IceCube-Gen2 point-like sensitivities. After investigating the prospects for detection of gamma-rays above TeV energies from these sources, we conclude that the joint observations of high-energy neutrinos and gamma-rays with upcoming telescopes will be an objective test for our emission model and may provide compelling evidence of star-forming activity as a tracer of neutrino production.