Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

  • M. G. Aartsen et al. (IceCube Collaboration), S. Abdollahi et al. (Fermi-LAT Collaboration), M. L. Ahnen et al. (MAGIC Collaboration), F. Lucarelli et al. (AGILE Team), K. Z. Stanek et al. (ASAS-SN Team), A. U. Abeysekara et al. (HAWC Collaboration), H. Abdalla et al. (H. E. S. S. Collaboration), V. Savchenko et al.(INTEGRAL Team), T. Morokuma et al. (Kanata, Kiso and Subaru Observing Teams), W. Keel et al. (Kapteyn Team), C. Copperwheat et al. (Liverpool Telescope Team), S. B. Cenko et al. (Swift/NuSTAR Team), A. U. Abeysekara et al. (VERITAS Collaboration), A. J. Tetarenko et al. (VLA/B Team)
  • Science 361, eaat1378 (2018)
  • 2018

Abstract

Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera–electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray–emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.

Science 361, eaat1378 (2018)
ArXiv pre-print

Auxiliary informations

H.E.S.S. performed a first set of follow-up observations towards the direction of the blazar TXS 0506+056 during the night of 22 September, 2017 (ATEL#10787). The observations started about 4h after the detection of a high-energy neutrino by IceCube (GCN 21916). A second set of observations was acquired during the nights of 27 September, 2017 and 28 September, 2017. In total 3.25 hours of high-quality observations including the central large telescope (CT5) were obtained at zenith angles ranging from 31 deg to 46 deg.

This dataset was analyzed in monoscopic mode using the Model Analysis (M. de Naurois, L. Rolland, Astropart. Physics 32, 231 (2009)) with loose cuts. No gamma-ray emission at a significant level was detected. The resulting maps of excess gamma rays and their significance are given below.

TXS0506+056 excess map:
[FITS]
[PNG]

TXS0506+056 significance map:
[FITS]
[PNG]

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