Tidal Disruption of Stars by SMBHs: A Laboratory for Studying Transient Accretion Disks
Abstract:
During a stellar tidal disruption event (TDE), a transient disk forms as stellar debris returns to the disruption site and circularizes, whose super-Eddington accretion powers a bright flare, broadcasting the sudden awakening of a dormant super-massive black hole (SMBH). To date ~15 TDE candidates have been discovered and the number is bound to increase dramatically with the advancement of transient astronomy. Not only a new window for demographic study of SMBHs, TDE also provides a testbed for accretion physics. I will describe a model for the evolution of the young TDE disk, by accounting for the time-dependent fallback rate, for the influence of wind losses in the early, super-critical stage, and for the possibility of thermal instability for accretion rates intermediate between the super-critical state and the standard Shakura-Sunyaev (SS) state. The model provides a dynamic basis for modeling TDE light curves. Application to the jetted TDE candidate Swift J1644+57 will be presented, whose apparent jet shutoff at t= 500 d we argue corresponds to a disk transition from the super-critical state to the SS state.