Lepto-hadronic γ-Ray and Neutrino Emission from the Jet of TXS 0506+056

Abstract

Abstract The observation of the IceCube-170922A event from the direction of TXS 0506+056 when it was in its enhanced γ-ray emission state offers a unique opportunity to investigate the lepto-hadronic processes in blazar jets. Here, the observed broadband emission of TXS 0506+056 is explained by boosted synchrotron/synchrotron self Compton emission from the jet, whereas the γ-ray data observed during the neutrino emission by inelastic interactions of the jet-accelerated protons in a dense gaseous target. The proton energy distribution is , calculated straightforwardly from the data obtained by the Fermi Large Area Telescope (Fermi-LAT) and the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC); if such a distribution continues up to E c,p = 10 PeV, the expected neutrino rate is as high as ∼0.46 events during the long active phase of the source or ∼0.15 if the activity lasts 60 days. In this interpretation, the energy content of the protons above >GeV in blazar jets can be estimated as well: the required proton injection luminosity is ≃2.0 × 1048 erg s−1 exceeding 103 times that of electrons ≃1045 erg s−1, which are in equipartition with the magnetic field. As the required parameters are physically realistic, this can be an acceptable model for an explanation of the neutrino and γ-ray emission from TXS 0506+056.