A Unified Relativistic Treatment of Tidal Disruption Events and a New Model for Self-Intersections Involving Tidal Debris Streams for Schwarzschild Black Holes

This dissertation concerns the astrophysical phenomena known as tidal disruption events~(TDEs), where stars are ripped apart by gravitational tides from their host galaxies' central supermassive black hole~(SBH). Stars are driven onto orbits appropriate for disruption via gravitational interactions with their stellar neighbors, and it is these interactions that determine the rate at which we may observe TDEs. Observations for such events have gained popularity in recent years, as they provide an additional avenue for probing the spacetime near non-active galactic centers. Conveniently, measurements for galactic transients are already underway, and have found, up to the publication of this dissertation, a few dozen TDE candidates. Theoretical predictions for TDEs have been conducted under both Newtonian gravity and general relativity, with numerical simulations of TDE rates and the post disruption stream evolution being common examples. Models for TDEs, however, have proven to be a greater challenge, as the phenomenon covers a wide range of length and time scales. With the recent increased interest in black holes due to gravitational-wave detection, correcting current TDE models to fall more in line with observations can only aid our understanding of these massive galactic objects.

The rest of this dissertation is as follows. Our first chapter will introduce the reader to some basic history of TDEs, from their inception as a means to feed mass into galactic centers to their modern interpretations. We also provide a brief overview of Newtonian loss-cone theory~(and its role in determining the rate at which TDEs are observed) and general relativity~(which is used to correct for relativistic effects in the aforementioned loss-cone theory). The second chapter comprises a published work concerning a unified treatment of TDEs that maps Newtonian predictions to their relativistically corrected counterparts. Our third chapter presents a new model where we track the evolution of the post-disruption tidal stream and provides predictions for observations of light curves. Our fourth chapter discusses a generalization of our work in Chapter 2 from the Schwarzschild metric to the Kerr metric, and we close with some concluding remarks.