2020/09/30 by Kohki Uno, Keiichi Maeda · 1 citation
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.3847/2041-8213/abca32
8 pages, 1 table, 4 figures, accepted for publication in the ApJL
arxiv created 2020/11/13 · arxiv updated 2020/12/16
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\rm SI) where the stellar debris stretched by the tidal force intersects; we show that the escape velocities at R\rm 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 10 ~M\odot\rm yr-1) from R\rm SI (∼ 1014\rm ~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\rm BH ∼ 104~M\odot).