2014/04/30 by Irene Tamborra, Shin'ichiro Ando, Kohta Murase · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Cosmic ray #Earth Systems and Cosmic Evolution #Fermi Gamma-ray Space Telescope #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminosity function #Neutrino #Neutrino astronomy #Spectral index #astro-ph.CO #astro-ph.GA #astro-ph.HE #hep-ph
paper · pdf · doi:10.1088/1475-7516/2014/09/043
published as JCAP 09 (2014) 043 · 26 pages, including 7 figures. Discussion expanded, new figures added. Accepted by JCAP
arxiv created 2014/08/29 · openalex publication_date 2014/09/25 · arxiv updated 2015/06/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Star-forming galaxies have been predicted to contribute considerably to the diffuse gamma-ray background as they are guaranteed reservoirs of cosmic rays. Assuming that the hadronic interactions responsible for high-energy gamma rays also produce high-energy neutrinos and that (100) PeV cosmic rays can be produced and confined in starburst galaxies, we here discuss the possibility that star-forming galaxies are also the main sources of the high-energy neutrinos observed by the IceCube experiment. First, we compute the diffuse gamma-ray background from star-forming galaxies, adopting the latest Herschel PEP/HerMES luminosity function and relying on the correlation between the gamma-ray and infrared luminosities reported by Fermi observations. Then we derive the expected intensity of the diffuse high-energy neutrinos from star-forming galaxies including normal and starburst galaxies. Our results indicate that starbursts, including those with active galactic nuclei and galaxy mergers, could be the main sources of the high-energy neutrinos observed by the IceCube experiment. We find that assuming a cosmic-ray spectral index of 2.1–2.2 for all starburst-like galaxies, our predictions can be consistent with both the Fermi and IceCube data, but larger indices readily fail to explain the observed diffuse neutrino flux. Taking the starburst high-energy spectral index as free parameter, and extrapolating from GeV to PeV energies, we find that the spectra harder than E -2.15 are likely to be excluded by the IceCube data, which can be more constraining than the Fermi data for this population.