The quest for the sources of the highest energy cosmic radiation is closely connected with the search for the production sites of high-energy astrophysical neutrinos, generated in cosmic ray interactions. In this pursuit, the IceCube Neutrino Observatory has been playing a leading role for over a decade, from the detection of hundreds of astrophysical neutrinos with energies reaching above the PeV, which marked the birth of high-energy neutrino astrophysics, to the identification of the blazar TXS 0506+056 as the first flaring extragalactic neutrino source candidate. Recently, an improved, more accurate analysis technique developed within the IceCube collaboration was used to search the northern sky for neutrino emission using ~9 years of re-calibrated data collected between 2011 and 2020. We searched for neutrino emission from 110 astrophysical objects known for being gamma-ray emitters and found the strongest clustering of neutrinos of high-energy neutrinos at the location of the Seyfert 2 galaxy NGC 1068, which shows evidence for neutrino emission at the 4.2 sigma level. After TXS 0506+056, NGC 1068 is the second extragalactic source of high-energy neutrinos, indicating that more than one population of sources contributes to the observed diffuse cosmic neutrino flux.
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Meeting ID: 984 5733 2925
Peter Thirolf (LMU) / Norbert Kaiser (TUM)