Evidence against star-forming galaxies as the dominant source of IceCube neutrinos
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9 pages
Published in:
- Astrophys.J. 836 (2017) 1, 47
- Published: Feb 7, 2017
e-Print:
- 1511.00688 [astro-ph.HE]
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Abstract: (IOP)
The cumulative emission resulting from hadronic cosmic-ray interactions in star-forming galaxies (SFGs) has been proposed as the dominant contribution to the astrophysical neutrino flux at TeV to PeV energies reported by IceCube. The same particle interactions also inevitably create γ-ray emission that could be detectable as a component of the extragalactic γ-ray background (EGB), which is now measured with the Fermi-LAT in the energy range from 0.1 to 820 GeV. New studies of the blazar flux distribution at γ-ray energies above 50 GeV place an upper bound on the residual non-blazar component of the EGB. We show that these results are in strong tension with models that consider SFGs as the dominant source of the diffuse neutrino backgrounds. A characteristic spectral index for parent cosmic rays in starburst galaxies of Γ(SB) ≃ 2.3 for is consistent with the observed scaling relation between γ-ray and IR luminosity for SFGs, the bounds from the non-blazar EGB, and the observed γ-ray spectra of individual starbursts, but underpredicts the IceCube data by approximately an order of magnitude.Note:
- 10 pages, 6 figures, 1 table, published in ApJ
- galaxies: starburst
- gamma rays: diffuse background
- neutrinos
- gamma ray: energy
- gamma ray: background
- neutrino: background
- neutrino: UHE
- neutrino: spectrum
- galaxy
- accelerator
References(73)
Figures(14)