  Supermassive black hole (SMBH) binaries residing at the core of merging
galaxies are recently found to be strongly affected by the rotation of their
host galaxies. The highly eccentric orbits that form when the host is
counterrotating emit strong bursts of gravitational waves that propel rapid
SMBH binary coalescence. Most prior work, however, focused on planar orbits and
a uniform rotation profile, an unlikely interaction configuration. However, the
coupling between rotation and SMBH binary evolution appears to be such a strong
dynamical process that it warrants further investigation. This study uses
direct N-body simulations to isolate the effect of galaxy rotation in more
realistic interactions. In particular, we systematically vary the SMBH orbital
plane with respect to the galaxy rotation axis, the radial extent of the
rotating component, and the initial eccentricity of the SMBH binary orbit. We
find that the initial orbital plane orientation and eccentricity alone can
change the inspiral time by an order of magnitude. Because SMBH binary inspiral
and merger is such a loud gravitational wave source, these studies are critical
for the future gravitational wave detector, LISA, an ESA/NASA mission currently
set to launch by 2034.
