Supermassive black holes appear to be generic components of galactic nuclei. Following their formation in the early universe, black holes should often find themselves in bound pairs as a consequence of galaxy mergers. The greatest uncertainty in estimating the coalescence time of black hole binaries is the degree to which a binary wanders about the center of the galactic potential. A simple model for binary decay is presented which qualitatively reproduces the evolution observed in the N-body simulations. The model predicts binary coalescence times that are never less than several billion years. Mass ejection by a decaying black hole binary should substantially lower the density of its host nucleus. The weak density cusps of bright ellipticals may be explained in this way if it is assumed that these galaxies formed from nearly gas-free mergers.
Date of creation, presentation, or exhibit
Department, Program, or Center
School of Physics and Astronomy (COS)
Merritt, David, "Black holes and galaxy evolution" (2000). Accessed from
RIT – Main Campus