A new multi-messenger description of starburst galaxies emission: perspectives for neutrino and gamma-ray observations

Star-forming and starburst galaxies (SBGs), which are well-known cosmic-ray (CR) reservoirs, are expected to emit gamma rays and neutrinos predominantly via hadronic collisions. In this work we analyze the 10-year Fermi-Low Energy Technique (LAT) spectral energy distributions of 13 nearby galaxies by means of a physical model that 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, which is in agreement with the available star formation rates coming from infrared (IR) and ultraviolet (UV) observations. Through this observation-based approach, we determine the most-likely neutrino counterparts from star-forming and SBGs and quantitatively assess the ability of current and upcoming neutrino telescopes to detect them as point-like sources. We also generate mock gamma-ray data to simulate the Cherenkov Telescope Array (CTA) performance in detecting these sources. Moreover, we propose a test to discriminate between the two different CR transport models for the starburst nuclei by looking at the different gamma-ray expectations. We point out that current data already gives a slight preference to CR models, which are dominated by advection.