Could TDE outflows produce the PeV neutrino events?

Abstract

The origin of ultra-high energy neutrinos still lacks observational evidence, besides, the physical mechanism is also unclear. There is an association of a PeV neutrino event (IceCube-191001A) with an optical tidal disruption event (TDE, AT2019dsg) which was detected 6 months ahead from IceCube-191001A. The numerical simulations and observations suggested that a TDE can produce ultrafast outflows, which will interact with clouds near the supermassive black hole. In this paper, we study the interactions between TDE outflows and clouds and the possible production. In the shock waves generated by the outflow-cloud interactions, protons can be accelerated to ∼ 60 PeV with the outflow velocity 0.07 c and kinetic luminosity 10 45 erg/s. PeV neutrinos can be produced through hadronic reactions. The calculation illustrates that the expected PeV neutrino event from AT2019dsg is 0.014 for a power-law proton energy distribution of Γ = 1.5 and 0.0016 for Γ = 1.9. The GeV -TeV γ-rays through hadronic processes are lower than the present observed limits. Outflows escaped from the TDE center colliding with clouds, which also can naturally explain the half-year delay between the neutrino event and TDE.