Ultrahigh energy neutrino scattering onto relic light neutrinos in galactic halo as a possible source of highest energy extragalactic cosmic rays

D. Fargion; B. Mele; A. Salis

doi:10.1086/307203

paper

Ultrahigh energy neutrino scattering onto relic light neutrinos in galactic halo as a possible source of highest energy extragalactic cosmic rays

arXiv:astro-ph/9710029 · doi:10.1086/307203

Abstract

The diffuse relic neutrinos with light mass are transparent to Ultrahigh energy (UHE) neutrinos at thousands EeV, born by photoproduction of pions by UHE protons on relic 2.73 K BBR radiation and originated in AGNs at cosmic distances. However these UHE $ν$ s may interact with those (mainly heaviest $ν_{μ_{r}}$ , $ν_{τ_{r}}$ and respective antineutrinos) clustered into HDM galactic halos. UHE photons or protons, secondaries of $ν ν_{r}$ scattering, might be the final observed signature of such high-energy chain reactions and may be responsible of the highest extragalactic cosmic-ray (CR) events. The chain-reactions conversion efficiency, ramifications and energetics are considered for the October 1991 CR event at 320 EeV observed by the Fly's Eye detector in Utah. These quantities seem compatible with the distance, direction and power (observed at MeV gamma energies) of the Seyfert galaxy MCG 8-11-11. The $ν ν_{r}$ interaction probability is favoured by at least three order of magnitude with respect to a direct $ν$ scattering onto the Earth atmosphere. Therefore, it may better explain the extragalactic origin of the puzzling 320 EeV event, while offering indirect evidence of a hot dark galactic halo of light (i.e., $m_{ν} \sim$ tens eV) neutrinos, probably of tau flavour.

25 pages, 1 figure minor corrections, updated references. In press in APJ

Ultrahigh energy neutrino scattering onto relic light neutrinos in galactic halo as a possible source of highest energy extragalactic cosmic rays

Abstract

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