Bridging the gap between the observed and intrinsic demographics of tidal disruption events

Abstract

This thesis shows that the disk formation processes in stellar tidal disruption events (TDEs) by massive black holes (MBHs) are crucial in altering the predicted TDE demographics. As the debris stream from a disrupted star intersects itself and dissipates orbital energy, it circularizes into an accretion disk. The efficiency of this process is determined by three key parameters — BH mass, stellar mass, and the orbital penetration parameter that specifies the orbit of the incoming stars. Based on the catalogue of the current well-known TDE candidates, there exists an indisputable tension between the raw observed distribution around their host BH masses and that theoretically predicted by stellar gravitational scattering mechanisms. By correlating the efficiency of the circularization process to our detectability of events, TDEs with prompt disk formation have significantly suppressed rates around lighter BHs, leading to a similar matching between the revised theoretical and observed distributions. A fuller version of the BH demographics could then be probed independently with TDE observation. Furthermore, the disk formation efficiency also alters the distributions of both the stellar mass and the orbital penetration parameter observed in TDEs.