Implications of a PeV neutrino spectral cutoff in GRB models

Maria Petropoulou; Dimitrios Giannios; Stavros Dimitrakoudis

doi:10.1093/mnras/stu1757

paper

Implications of a PeV neutrino spectral cutoff in GRB models

arXiv:1405.2091 · doi:10.1093/mnras/stu1757

Abstract

The recent discovery of extragalactic PeV neutrinos opens a new window to the exploration of cosmic-ray accelerators. The observed PeV neutrino flux is close to the Waxman-Bahcall upper bound implying that gamma-ray bursts (GRBs) may be the source of ultra-high energy cosmic rays (UHECRs). Starting with the assumption of the GRB-UHECR connection, we show using both analytical estimates and numerical simulations that the observed neutrinos can originate at the jet as a result of photopion interactions with the following implications: the neutrino spectra are predicted to have a cutoff at energy $\leq 10$ PeV; the dissipation responsible for the GRB emission and cosmic-ray acceleration takes place at distances $r_{diss} \approx 3 \times 1 0^{11} - 3 \times 1 0^{13} cm$ from the central engine; the Thomson optical depth at the dissipation region is $τ_{T} \sim 1$ ; the jet carries a substantial fraction of its energy in the form of Poynting flux at the dissipation region, and has a Lorentz factor $Γ ≃ 100 - 500$ . The non-detection of $\sim$ PeV neutrinos coincident with GRBs will indicate that GRBs are either poor cosmic accelerators or the dissipation takes place at small optical depths in the jet.

12 pages, 8 figures, 1 table, 1 appendix, accepted in MNRAS

Implications of a PeV neutrino spectral cutoff in GRB models

Abstract

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