  The study of how stars distribute themselves around a massive black hole
(MBH) in the center of a galaxy is an important prerequisite for the
understanding of many galactic-center processes. These include the observed
overabundance of point X-ray sources at the Galactic center, the prediction of
rates and characteristics of tidal disruptions of extended stars by the MBH and
of inspirals of compact stars into the MBH, the latter being events of high
importance for the future space borne gravitational wave interferometer LISA.
In relatively small galactic nuclei, hosting MBHs with masses in the range
10^5-10^7 Msun, the single most important dynamical process is 2-body
relaxation. It induces the formation of a steep density cusp around the MBH and
strong mass segregation, as more massive stars lose energy to lighter ones and
drift to the central regions. Using a spherical stellar dynamical Monte-Carlo
code, we simulate the long-term relaxational evolution of galactic nucleus
models with a spectrum of stellar masses. Our focus is the concentration of
stellar black holes to the immediate vicinity of the MBH. We quantify this mass
segregation for a variety of galactic nucleus models and discuss its
astrophysical implications. Special attention is given to models developed to
match the conditions in the Milky Way nucleus; we examine the presence of
compact objects in connection to recent high-resolution X-ray observations.

Astrophysics