  Traditionlly, gravitational wave emission from a coalescing binary system is
computed using point mass approximations without considering any accretion
disk. However, it is believed that in many of the galactic nuclei, there are
supermassive central black holes surrounded by accretion disks. These accretion
disks must be necessarily supersonic on and outside the horizon simply because
the radial velocity (in the corotating frame) has to be the velocity of light
on the horizon while the sound speed must be smaller. However, supersonic flows
are typically sub-Keplerian. Thus, smaller black holes and neutron stars (which
are on instantaneously Keplerian orbit and lose energy and angular momentum
through gravitational radiation) on their way to coalesce with the central
black hole must accrete negative angular momentum from the disk. We study here
the way these disks affect the gravitational wave emission.
