First Observation of PeV-Energy Neutrinos with IceCube
Abstract
We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04±0.16 and 1.14±0.17PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current νe,μ,τ (ν¯e,μ,τ) or charged-current νe (ν¯e) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082±0.004(stat)-0.057+0.041(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9×10-3 (2.8σ) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time.
- Publication:
-
Physical Review Letters
- Pub Date:
- July 2013
- DOI:
- 10.1103/PhysRevLett.111.021103
- arXiv:
- arXiv:1304.5356
- Bibcode:
- 2013PhRvL.111b1103A
- Keywords:
-
- 95.85.Ry;
- 95.55.Vj;
- 98.70.Sa;
- Neutrino muon pion and other elementary particles;
- cosmic rays;
- Neutrino muon pion and other elementary particle detectors;
- cosmic ray detectors;
- Cosmic rays;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Extragalactic Astrophysics
- E-Print:
- 7 pages, 5 figures, 1 table, accepted for publication in Physical Review Letters