Stars Versus Quasar Accretion Disks

This thesis investigates the astrophysical effects of stars colliding with the accretion disks of supermassive black holes (SMBH) in active galactic nuclei (AGN). In this work, we model the AGN to have a thin accretion disk surrounded by a stellar nuclear cluster (SNC) containing stars on various orbital eccentricities and inclination angles striking the disk at periapse. An impacting star carves a tilted cylindrical tunnel out of the disk material and loses up to $6\times 10-4\%$ of its stellar mass. The time-averaged collisional luminosity is at most $10-2$ times the entire disk's expected luminosity, while the emission profile of an impact site initially flares before quickly dimming to the brightness of the local disk. The parameters of the SMBH, accretion disk, SNC, and impacting stars are altered to reveal that star-disk collisions from a densely populated SNC can outshine the disk luminosity.