IceCube: Cosmic Neutrinos and Multimessenger Astronomy

Professor Francis Halzen (Wisconsin IceCube Particle Astrophysics Center and the Department of Physics, University of Wisconsin–Madison)

Below the geographic South Pole, the IceCube project has transformed one cubic kilometer of natural Antarctic ice into a neutrino detector. IceCube detects more than 100,000 neutrinos per year in the GeV to 10 PeV energy range. From those, we have isolated a flux of high-energy neutrinos of cosmic origin, with an energy flux that is comparable to that of high-energy photons. We have also identified the first source: on September 22, 2017, following an alert initiated by a 290-TeV neutrino, observations by other astronomical telescopes pinpointed a flaring active galaxy, powered by a supermassive black hole. We will review recent progress in measuring the cosmic neutrino spectrum and in identifying its origin.