ASTRONOMY COLLOQUIUM

Most galaxies contain a super massive black hole at their centers, with masses of millions to billions times that of our sun, surrounded by a dense cluster of stars and stellar mass black holes. We discuss how scattering and emission of gravitational waves affect the stellar distribution around supermassive black holes, and derive the statistical equilibrium state. We discuss the implications of this state to extreme events, observable from galactic centers in the universe. These include gravitational waves in the LISA band, tidal disruption of stars, ejection of hypervelocity stars, stable and unstable mass transfer from stars into the supermassive black hole and mysterious pulses of x-rays known as quasi periodic eruptions.