A new multimessenger study of Starburst galaxies: a closer look to expecting neutrinos

Abstract

Considering the high star formation rate (up to 100 M⊙/year) of starburst galaxies (SBGs), they are well posed between the guaranteed “factories” of high energy neutrinos, since they can contain accelerated cosmic rays in the central region where the high-density gas is present. A more accurate description of their possible hadronic emission could help to better explain the diffuse astrophysical flux measured by IceCube as well as the observed point-like excess, like the case of NGC1068. With this in mind we report here a multi-messenger study, looking at diffuse and resolved gamma-ray and neutrino measurements, that explain the very-high-energy (VHE) emission through a calorimetric scenario. For the analysis of the diffuse component we perform a blending of the available spectral indexes and produce a multi-component study of extragalactic background light (EGB), high energy starting events (HESE) and high-energy cascade IceCube data. In contrast to common prototype scenarios, the spectral index blending leads to a non negligible diffuse neutrino component from SBGs, accounting up to 40% of the HESE events, at 95.4% CL. This scenario privileges also a maximal energy within tens of PeV for the accelerated charge particles inside these galaxies. For the point-like study we report the proposed calorimetric description for the gamma-ray resolved SBGs within 100 Mpc, taking into account the star formation rate derived from their infrared emission. These neutrino expectations are then compared with the sensitivity of IceCube, IceCube/Gen2 and the incoming KM3NeT.