Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector

TLDR

The study builds on earlier detection of two PeV neutrinos, extending sensitivity to about 30 TeV. An all‑sky search for high‑energy neutrino interactions in IceCube was performed from May 2010 to May 2012. Twenty‑six new high‑energy neutrino events were found, bringing the total to 28 and rejecting a purely atmospheric origin at 4σ; their energies, flavors, and directions match expectations for an extraterrestrial component.

Abstract

We report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4σ level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.