Opening a New Window onto the Universe with IceCube

TL;DR

IceCube is a large-scale neutrino detector in Antarctic ice that has discovered cosmic neutrinos, opening new avenues for multimessenger astronomy and understanding high-energy astrophysical phenomena.

Contribution

The paper reports the successful detection of high-energy cosmic neutrinos using IceCube, demonstrating the feasibility of kilometer-scale neutrino telescopes in Antarctic ice.

Findings

Detection of a flux of cosmic neutrinos from 10 TeV to 10 PeV.

Neutrino flux is predominantly extragalactic in origin.

Energy density of neutrinos is comparable to gamma rays and cosmic rays.

Abstract

Weakly interacting neutrinos are ideal astronomical messengers because they travel through space without deflection by magnetic fields and, essentially, without absorption. Their weak interaction also makes them notoriously difficult to detect, with observation of high-energy neutrinos from distant sources requiring kilometer-scale detectors. The IceCube project transformed a cubic kilometer of natural Antarctic ice at the geographic South Pole into a Cherenkov detector. It discovered a flux of cosmic neutrinos in the energy range from 10 TeV to 10 PeV, predominantly extragalactic in origin. Their corresponding energy density is close to that of high-energy photons detected by gamma-ray satellites and ultra-high-energy cosmic rays observed with large surface detectors. Neutrinos are therefore ubiquitous in the nonthermal universe, suggesting a more significant role of protons (nuclei) relative to electrons than previously anticipated. Thus, anticipating an essential role for multimessenger astronomy, IceCube is planning significant upgrades of the present instrument as well as a next-generation detector. Similar detectors are under construction in the Mediterranean Sea and Lake Baikal.