Neutrino emission from an off-axis jet driven by the tidal disruption event AT2019dsg

Abstract

Recently, a high-energy muon neutrino event was detected in association with a tidal disruption event (TDE) AT2019dsg at the time about 150 days after the peak of the optical/UV luminosity. We propose that such a association could be interpreted as arising from hadronic interactions between relativistic protons accelerated in the jet launched from the TDE and the intense radiation field of TDE inside the optical/UV photosphere, if we are observing the jet at a moderate angle (i.e., approximately 10-30 degree) with respect to the jet axis. Such an off-axis viewing angle leads to a high gas column density in the line of sight which provides a high opacity for the photoionization and the Bethe-Heitler process, {and allows the existence of an intrinsic long-term X-ray radiation of comparatively high emissivity}. As a result, the cascade emission accompanying the neutrino production, which would otherwise overshoot the flux limits in X-ray and/or GeV band, is significantly obscured or absorbed. Since the jets of TDEs are supposed to be randomly oriented in the sky, the source density rate of TDE with an off-axis jet is significantly higher than that of TDE with an on-axis jet. Therefore, an off-axis jet is naturally expected in a nearby TDE being discovered, supporting the proposed scenario.