Neutrino production in starburst galaxies

Abstract

Understanding the origin of the diffuse flux of high-energy astrophysical neutrinos detected by IceCube has become a challenging issue within present High Energy Astrophysics. In this work, we present a model to explore the potential neutrino emission of starburst galaxies (SBG) by considering three different neutrino production zones that can be associated to a typical single SBG. The first zone is the starburst nucleus (SBN), where due to the high rate of supernova explosions, a significant amount of protons can be accelerated to high energies and undergo $pp$ interactions with cold protons of the interstellar medium. The second zone we consider is the corresponding to the starburst wind (SBW), which is formed by the hot gas that emerges from the nucleus and interacts with the intergalactic medium (IGM) generating shocks. Protons accelerated there can undergo $pp$ interactions with the ambient matter. The third neutrino production zone we consider, is an external one, where we account for the possibility that protons escaping from the whole system interact with the cosmic microwave background (CMB). Finally, adding the neutrino contributions of the three zones, we calculate the diffuse neutrino flux and the diffuse photon flux by integration on the redshift range appropriate for SBG. We find that the model behaves well applied to nearby galaxies such as M82 and NGC 253. The contributions made to the diffuse neutrino flux are able to explain part of the data provided by IceCube if typical parameters are considered.