Neutrino emission from the direction of the blazar TXS 0506+056 prior to the IceCube-170922A alert
IceCube Collaboration; Aartsen, M. G.; Ackermann, M.; Adams, J.; Paolo Giommi
Jul - 2018
DOI: 10.1126/science.aat2890

journal : Science

Volume : 361 ; Issue : 6398
type: Article Journal

Abstract
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.

keywords : Astrophysics - High Energy Astrophysical Phenomena; High Energy Physics - Experiment