University of Wisconsin-Madison

Observation of Astrophysical Neutrinos in Four Years of IceCube Data (released 21 Oct 2015)

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Observation of Astrophysical Neutrinos in Four Years of IceCube Data (preview)

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The spectrum of cosmic rays includes the most energetic particles ever observed. The mechanism of their acceleration and their sources are, however, still mostly unknown. Observing astrophysical neutrinos can help solve this problem. Because neutrinos are produced in hadronic interactions and are neither absorbed nor deflected, they will point directly back to their source.

Here we present an update to the IceCube high-energy search for events with interaction vertices inside the detector fiducial volume. This search, previously performed on two years of detector data, led to the discovery of an astrophysical neutrino flux above atmospheric backgrounds. This update extends the data-taking period by one more year to four years from 2010 to 2014 for a total livetime of 1347 days.

Observation of High-Energy Astrophysical Neutrinos in Three Years of IceCube Data, IceCube Collaboration, Phys. Rev. Lett. 113, 101101 (2014).

See paper on the PRL site.

Observation of Astrophysical Neutrinos in FourYears of IceCube Data, IceCube Collaboration, Proceedings of Science (ICRC2015)1081.

See paper on arXiv.

Data release

Observation of Astrophysical Neutrinos in Four Years of IceCube Data (.txt)

Included in the download is the following file:

  • eventsummary_4years.txt - Properties of the events observed in the four years of IceCube data. The “Edep” column shows the electromagnetic-equivalent deposited energy of each event. “Ang. Err.” Shows the median angular error including systematic uncertainties. Event times are given as fractional MJD.

See the data release of the initial two-year search, published in Science, for the neutrino effective areas for the individual neutrino flavors after analysis cuts.

For any questions about this data release, please write to