Fermi Gamma-ray Space Telescope

Calorimetric Assessment of Neutrino-Blazar Associations

Matthias Kadler
(M. Kreter, K. Mannheim, S. Buson, F. Krauß, R. Ojha, E. Ros)


TXS 0506+056 is the second high-fluence blazar that has been associated with a neutrino in the 100 TeV to 10 PeV range detected by IceCube, following the previous association of the blazar PKS 1424−418 with the 2 PeV neutrino ’BigBird’. The PKS 1424−418/BigBird association was at a significance of about 2sigma and was explained with a physical model based on a predicted proportionality between the integrated keV-to-GeV gamma-ray fluence and the neutrino fluence produced in the presence of high-energy protons in blazar jets whose interaction with a UV photon field give rise to photopion production. Here, we determine the expected neutrino detection rate for TXS 0506+056 based on this a-priori-defined model. We show that the association of the IC170922A neutrino with TXS 0506+056 is energetically plausible, i.e., that the single source TXS 0506+056 is capable of producing a neutrino flux high enough to explain the detection of a single event at 290TeV with IceCube. From our predefined model, we derive the joint chance probability for the two blazar-neutrino coincidences, supporting the idea that high-fluence blazars are indeed the first identified class of extragalactic neutrino point sources.