Abstract:
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. Among those, we have isolated a flux of high-energy neutrinos originating beyond our Galaxy, with an energy flux that is comparable to that of the extragalactic high-energy photon flux observed by the NASA Fermi satellite. With a decade of data, we have identified their first sources, which point to the obscured dense cores associated with the supermassive black holes at the centers of active galaxies as the origin of high-energy neutrinos and high-energy cosmic rays. We recently observed neutrinos originating in our own Milky Way.
Biography:
Francis Halzen is a Vilas and Gregory Breit Distinguished Professor of Physics at the University of Wisconsin–Madison.
Born in Belgium, Halzen received his Master’s and PhD degrees from the KUL Leuven, Belgium, and has been on the physics faculty at UW–Madison since 1972. He is the recipient of numerous awards, including the 2014 Smithsonian American Ingenuity Award, the 2015 Balzan Prize, a 2018 Bruno Pontecorvo Prize, the 2021 Rossi Prize of the American Astronomical Society, and honorary doctorates at several universities.
Halzen is the Principal Investigator of IceCube, a cubic-kilometer neutrino telescope buried in the Antarctic ice at the South Pole. IceCube’s first observations of high-energy cosmic neutrinos garnered the 2013 Physics World Breakthrough of the Year Award. In September 2017, IceCube detected a high-energy neutrino from the direction of an active galaxy called TXS 0506+056. This was the first-ever direct evidence of a source of high-energy cosmic rays.
Halzen is the co-author of Quarks and Leptons, a classic textbook on modern particle physics that continues to be used extensively throughout college campuses today.
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