We investigate a purely stellar dynamical solution to the Final Parsec Problem .
Galactic nuclei resulting from major mergers are not spherical , but show some degree of triaxiality .
With N -body simulations , we show that massive black hole binaries ( MBHB ) hosted by them will continuously interact with stars on centrophilic orbits and will thus inspiral—in much less than a Hubble time—down to separations at which gravitational wave ( GW ) emission is strong enough to drive them to coalescence .
Such coalescences will be important sources of GWs for future space-borne detectors such as the Laser Interferometer Space Antenna ( LISA ) .
Based on our results , we expect that LISA will see between \sim 10 to \sim { few } \times 10 ^ { 2 } such events every year , depending on the particular MBH seed model as obtained in recent studies of merger trees of galaxy and MBH co-evolution .
Orbital eccentricities in the LISA band will be clearly distinguishable from zero with e \gtrsim 0.001 - 0.01 .