Explaining X-ray reverberation of the TDE Swift J1644+57 with super-Eddington accretion flow

X-ray reverberation is a proven technique capable of probing the innermost region of accretion disks around compact objects. Current theoretical effort assumes that the disk is geometrically thin, optically thick and rotating at Keplerian speed. Thus, these theoretical models cannot be applied to super-Eddington accretion systems because the thin disk approximation fails in this high accretion regime. State-of-the-art numerical simulations of super-Eddington accretion show optically thick winds being launched from the geometrically and optically thick disks. Therefore, the reflection geometry of the super-Eddington case is morphologically different from the thin disk picture, and, thus, we need new theoretical methods to handle X-ray reverberation on super-Eddington accretors. An example of super-Eddington accretors are Tidal Disruption Events (TDEs). A TDE happen when a star passes too close to a black hole where it will be ripped apart into elongated gas streams due to tidal forces from the black hole. Around half the gas remains bound to the black hole and will eventually form an accretion disk. In most TDEs, gas is believed to be accreted onto the black hole at super-Eddington rates.

In this talk, I will present a case study of the jetted Tidal Disruption Event (TDE), Swift J1644+57, and show the observation is consistent with the theoretical prediction of X-ray reverberation of super-Eddington accretors and that the model provides a better fit than the standard thin disk.