We present N-body simulations of mergers of galactic nuclei
with MBHs. We discuss the time evolution of the orbital elements of the
MBHB, as well as the evolution of the surrounding stellar environment.
Based on the N-body results, we derive a simplified analytic model for
the MBHB evolution. This model can be incorporated into cosmological
simulations from which the growth history of MBHs can be followed. From
the cosmological simulations, we will estimate the expected GW signal,
due to the inspiral and coalescence of MBHBs, for LISA.

(in collaboration with: Jose' Pacheco & Charline Filloux (OCA), Rainer
Spurzem (ARI))