Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A
Following the detection of a high-energy muon neutrino (IceCube-170922A) by the IceCube Neutrino Observatory, follow-up observations across the electromagnetic spectrum identified a spatially coincident gamma-ray flare from the blazar TXS 0506+056. The joint detection provided the first compelling evidence associating a high-energy astrophysical neutrino with a specific source, identifying blazars as cosmic-ray accelerators. The work is a landmark in multimessenger astronomy.