2015ApJ...805...95C

Star-forming galaxies, due to their high star formation rates, and hence large number of supernova remnants (SNRs) therein, are huge reservoirs of cosmic rays (CRs). These CRs collide with gases in galaxies and produce high-energy neutrinos through proton-proton collisions. In this paper, we calculate the neutrino production efficiency in star-forming galaxies by considering realistic galaxy properties, such as the gas density and galactic wind in star-forming galaxies. To calculate the accumulated neutrino flux, we use the infrared luminosity function of star-forming galaxies recently obtained by the Herschel PEP/HerMES survey. The intensity of CRs producing PeV neutrinos in star-forming galaxies is normalized with the observed CR flux at EeV (1 EeV = 10¹⁸ eV), assuming that SNR or hypernova remnants in star-forming galaxies can accelerate protons to EeV energies. Our calculations show that the accumulated neutrino emission produced by CRs in star-forming galaxies can account for the flux and spectrum of the sub-PeV/PeV neutrinos under reasonable assumptions on the CR confinement time in these galaxies.