Neutrino emission from the direction of the blazar TXS 0506+056 prior to the IceCube-170922A alert

• Main Authors: Arguelles Delgado, Carlos A (Author), Axani, Spencer Nicholas (Author), Collin, G. H (Author), Conrad, Janet Marie (Author), Moulai, Marjon H. (Author), IceCube Collaboration (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Department of Nuclear Science and Engineering (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Association for the Advancement of Science (AAAS), 2021-01-11T21:25:26Z.
• Subjects: Article
• Online Access: Get fulltext

A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. Prompted by this association, we investigated 9.5 years of IceCube neutrino observations to search for excess emission at the position of the blazar. We found an excess of high-energy neutrino events, with respect to atmospheric backgrounds, at that position between September 2014 and March 2015. Allowing for time-variable flux, this constitutes 3.5σ evidence for neutrino emission from the direction of TXS 0506+056, independent of and prior to the 2017 flaring episode. This suggests that blazars are identifiable sources of the high-energy astrophysical neutrino flux.