Evolution of Binary Supermassive Black Holes via Chain Regularization
  A chain regularization method is combined with special purpose computer hardware to study the evolution of massive black hole binaries at the centers of galaxies. Preliminary results with up to N=260,000 particles are presented. The decay rate of the binary is shown to decrease with increasing N, as expected on the basis of theoretical arguments. The eccentricity of the binary remains small. 
Andras Szell, David Merritt, Seppo Mikkola