par Aartsen, M. G.;Aguilar Sanchez, Juan Antonio
;Ansseau, Isabelle
;Baur, Sebastian
;Heereman von Zuydtwyck, David
;Iovine, Nadège
;Maris, Ioana Codrina
;Meures, Thomas
;Mockler, Daniela
;O'Murchadha, Aongus
;Pinat, Elisa
;Raab, Christoph
;Renzi, Giovanni
;Toscano, Simona ![](/vufind/images/ULB/publications_list.png)
Référence Physical review letters, 125, 12, 121104
Publication Publié, 2020-09-01
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Référence Physical review letters, 125, 12, 121104
Publication Publié, 2020-09-01
Article révisé par les pairs
Résumé : | We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of φastro=1.66-0.27+0.25 at E0=100 TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100 TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100 TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays. |