Could TDE outflows produce the PeV neutrino events?

Abstract

A tidal disruption event (TDE), AT2019dsg, was observed to be associated with a PeV neutrino event, IceCube-191001A, lagging the optical outburst by a half year. It is known that TDEs may generate ultrafast outflows. If the TDE occurs in a cloudy environment, the outflow-cloud interactions may form shock waves which generate accelerated protons and hence delayed neutrinos from hadronic interactions in clouds. Here we investigate the neutrino production in AT2019dsg by examining the TDE outflow-cloud interaction model. We find that, for an outflow with a velocity of 0.07c and a kinetic luminosity of $10^{45}\rm erg\ s^{-1}$, protons may be accelerated up to ∼ 60 PeV by the bow shocks, and generate PeV neutrinos by interactions with clouds. The predicted neutrino number in this model depends on the uncertainties of model parameters and in order to match the observations, some challenging values of parameters have been involved. The PeV neutrino event number can be ∼4 × 10−3 for a hard proton index Γ = 1.5.

Interpretation of the Observed Neutrino Emission from Three Tidal Disruption Events

“…In the hidden wind models, pp interactions with the debris can also play a major role; however, large uncertainties are implied, such as from the geometry and the time evolution of the system. There are also some similarities with the TDE outflow model for AT2019dsg in Wu et al (2022): outflow-cloud interactions may lead to particle acceleration, and pp interactions with the clouds may lead to neutrino production. While the production region in that model is a bit larger (R ; 10 16 cm), the pp interactions are efficient in the clouds, which are assumed to have a size of about ;10 14 cm and act as calorimeters.…”

“…TDEs may also be candidates to accelerate and even power the UHECRs (Farrar & Gruzinov 2009;Farrar & Piran 2014;Zhang et al 2017;Biehl et al 2018b;Guépin et al 2018). For AT2019dsg, jets (Liu et al 2020;Winter & Lunardini 2021), outflow-cloud interactions (Wu et al 2022), disk, corona, hidden winds, or jets (Murase et al 2020b) have been proposed (see Hayasaki 2021 for an overview). While a collimated outflow, such as a jet, has the advantage that it can provide the necessary power for the neutrino emission (see discussion in Winter & Lunardini 2022), no convincing direct jet signatures for AT2019dsg have been observed (Mohan et al 2022), and the observed radio signal might only be interpreted as a jet signature in scenarios with purely leptonic radiative signatures for an unnaturally narrow jet (Cendes et al 2021) or a steep density profile (Cannizzaro et al 2021).…”

Choked Jets in Expanding Envelope as the Origin of the Neutrino Emission Associated with Tidal Disruption Events

“…The nondetection of any jet emission at early time in AT2019dsg may be due to that the jet formation is also delayed (Cendes et al 2022). In addition, the neutrino emission from AT2019dsg could be due to successful on-axis or off-axis jets or other processes (Liu et al 2020;Murase et al 2020;Winter & Lunardini 2021;Wu et al 2022).…”

“…Neutrino emission is predicted to be produced in both successful jets (Wang et al 2011;Wang & Liu 2016;Dai & Fang 2017;Lunardini & Winter 2017;Senno et al 2017) and choked jets of TDEs (Wang & Liu 2016;Senno et al 2017). After the identification of AT2019dsg/ IC191001A, TDE jets (Liu et al 2020;Winter & Lunardini 2021), corona and hidden wind (Murase et al 2020), and outflow-cloud interactions (Wu et al 2022) have been proposed to explain the neutrino emission. While a successful jet has the advantage that it can provide the necessary power for the neutrino emission (see the discussion in Winter & Lunardini 2022), no convincing direct jet signatures for AT2019dsg have been observed (Mohan et al 2022).…”

Quasi-perpendicular Shock Acceleration and Tidal Disruption Event Radio Flares

“…TDEs have been suggested as candidates for producing highenergy protons and neutrinos (Murase et al 2020b), which is also supported by recently reported neutrino events associated with TDEs (e.g., Reusch et al 2022;Stein et al 2021;van Velzen et al 2021). However, with a steep spectrum of highenergy protons, it would be difficult for TDE outflows to account for the observed PeV neutrinos (Wu et al 2022). It suggests that in addition to the shock obliquity, other physical ingredients, e.g., cosmic-ray diffusion and feedback, may affect the acceleration of energetic protons.…”