A Search for Ultra-high-energy Neutrinos from TXS 0506+056 Using the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION, INCLUYE S MOLLERACH

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2020

0004-637X

Results of a search for ultra-high-energy neutrinos with the Pierre Auger Observatory from the direction of theblazar TXS 0506+056 are presented. They were obtained as part of the follow-up that stemmed from the detectionof high-energy neutrinos and gamma rays with IceCube, Fermi-LAT, MAGIC, and other detectors ofelectromagnetic radiation in several bands. The Pierre Auger Observatory is sensitive to neutrinos in the energyrange from 100 PeV to 100 EeV and in the zenith-angle range from θ=60° to θ=95°, where the zenith angle ismeasured from the vertical direction. No neutrinos from the direction of TXS 0506+056 have been found. Theresults were analyzed in three periods: one of 6 months around the detection of IceCube-170922 A, coinciding witha flare period of TXS 0506+056, a second one of 110 days during which the IceCube collaboration found anexcess of 13 neutrinos from a direction compatible with TXS 0506+056, and a third one from 2004 January 1 upto 2018 August 31, over which the Pierre Auger Observatory has been taking data. The sensitivity of theObservatory is addressed for different spectral indices by considering the fluxes that would induce a singleexpected event during the observation period. For indices compatible with those measured by the IceCubecollaboration the expected number of neutrinos at the Observatory is well below one. Spectral indices as hard as1.5 would have to apply in this energy range to expect a single event to have been detected.