Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk at 3:45 PM
Speaker: Fabio Antonini, Northwestern University
Abstract: Massive stellar clusters are often found at the photometric and kinematic centers of galaxies. Such nuclear clusters are the densest stellar systems observed in the local universe, representing a natural environment where compact object binaries can dynamically form, harden and merge. I will discuss the dynamical processes that lead to the merger of black hole binaries in nuclear clusters in connection to the origin of the binary black hole mergers recently detected by Advanced LIGO. I will show that nuclear clusters can produce a significant population of black hole binaries that merge in the local universe, and that these binaries have clear differences in the statistical distributions of their properties (e.g., mass, eccentricity) when compared to those formed either in globular clusters or through isolated binary evolution. Finally, I will consider the evolution of supermassive black hole binaries that are formed in nuclear clusters during the merger of galaxies. The results of N-body and Monte Carlo simulations show that coalescence times fall in the range from 10^8 yr to a few Gyr. These results constitute a fully stellar-dynamical solution to the ''final-parsec problem'' and imply a high rate of events for planned low-frequency gravitational wave detectors like eLISA.