Application of The Wind-Driven Model to A Sample of Tidal Disruption Events

Abstract

An origin of the Optical/UV radiation from tidal disruption events (TDEs) has recently been discussed for different scenarios, but observational support is generally missing. In this Letter, we test applicability of the `Wind-Driven model' (Uno & Maeda 2020) to a sample of UV/Optical TDEs. With the model, we aim to derive the physical properties of the Optical/UV TDEs, such as mass-loss rates and characteristic radii. The model assumes optically thick continuous outflows like stellar winds, and one key question is how the wind-launched radius is connected to physical processes in TDEs. As one possibility, through a comparison between the escape velocities estimated from their black-hole masses and the wind velocities estimated from observed line widths, we propose that the outflow is launched from the self-interaction radius ($R_{\mathrm{SI}}$) where the stellar debris stretched by the tidal force intersects; we show that the escape velocities at $R_{\mathrm{SI}}$ are roughly consistent with the wind velocities. By applying the model to a sample of Optical/UV TDE candidates, we find that explosive mass ejections ($\gtrsim 10M_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$) from $R_{\mathrm{SI}}$ ($\sim 10^{14}\mathrm{cm}$) can explain the observed properties of TDEs around peak luminosity. We also apply the same framework to a peculiar transient, AT2018cow. The model suggests that AT2018cow is likely a TDE induced by an intermediate-mass black hole ($M_{\mathrm{BH}}\sim 10^4{M}_{\odot }$).

8 pages, 1 table, 4 figures, accepted for publication in the ApJL

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• Radiative hydrodynamical simulations of super-Eddington accretion flow in tidal disruption event: the accretion flow and wind
• Real-time Discovery of AT2020xnd: A Fast, Luminous Ultraviolet Transient with Minimal Radioactive Ejecta
• Probing the tidal disruption event iPTF16axa with CLOUDY and disc-wind models
• The spectra of a radiative reprocessing outflow model for fast blue optical transients
• Luminous Fast Blue Optical Transients as "Failed" Gravitational-wave Sources: Helium Core$-$Black Hole Mergers Following Delayed Dynamical Instability
• Light-curve Modelling for The Initial Rising Phase of Rapidly-evolving Transients Powered by Continuous Outflow