N-body studies of galactic nuclei with massive black holes

Abstract

Massive black holes (MBHs) are ubiquituous in galactic nuclei. The collisional dynamics of these $systems is studied with high resolution, direct $N$-body simulations and its results are thorough$those obtained from the Fokker-Planck equation, written in energy space. The predictions from the$equation are validated by the $N$-body results and it is concluded that the formation of a Bahcal$a MBH is a robust prediction for the old stellar populations of spheroidal systems older than the$as measured at the hole's influence radius. The mass segregation and the scaling relations predic$different mass ranges are also confirmed. $N$-Body simulations of galaxy mergers show that binary MBHs can form with very high eccentriciti$galaxies settle into a newly merged nucleus. These high eccentricities should lead to a coalescen$time scale, as the MBHs should emmit strong bursts of gravitational waves at each pericenter pass$harmonics of the gravitational wave strain amplitude $h$ are estimated as the massive binary with mass $\sim 1$enters the Laser Interferometer Space Antenna (LISA) frequency band. We conclude that large-scale $N$-body modelling of galactic nuclei with one (several) MBH(s) is p$currently available software (Sverre Aarseth's NBODY codes and developments therefrom) and hardwa$cluster).