Abstract

Dynamical friction is a fundamental process in astrophysics and its understanding is arguably the most important contribution of Chandrasekhar to stellar dynamics. In this talk I will discuss the results of analytical models and N-body simulations that describe the evolution of a massive black hole binary due to dynamical friction. I will show that the standard Chandrasekhar’s theory leads to erroneous conclusions about the evolution of the massive binary because the usual simplifying assumptions that lead to neglect the contribution of stars with large velocities appear to break down. I will discuss the implications of our results for a number of observational puzzles, which include the presence of multiple nuclei in bright ellipticals, off-center AGNs and eccentric nuclear disks.