A concordance scenario for the observed neutrino from a Tidal Disruption Event

During a tidal disruption event, a star is torn apart by the tidal forces of a supermassive black hole, with about 50% of the star's mass eventually accreted by the black hole. The resulting flare can, in extreme cases of super-Eddington mass accretion, result in a relativistic jet. While tidal disruption events have been theoretically proposed as sources of high-energy cosmic rays and neutrinos, stacking searches indicate that their contribution to the diffuse extragalactic neutrino flux is very low. However, a recent association of a track-like astrophysical neutrino with a tidal disruption event (AT2019dsg) indicates that some tidal disruption events can accelerate cosmic rays to PeV energies. Here we introduce a phenomenological concordance scenario with a relativistic jet to explain this association: an expanding cocoon progressively obscures the X-rays emitted by the accretion disk, while at the same time providing a sufficiently intense external target of back-scattered X-rays for the production of neutrinos via proton-photon interactions. We also reproduce the delay (relative to the peak) of the neutrino emission by scaling the production radius with the black body radius. Our energetics and assumptions for the jet and the cocoon are compatible with expectations from numerical simulations of tidal disruption events.