  It is believed that most quasars and galaxies present two common features:
the presence in their core of a supermassive object, and the experience of one
or more encounters with other galaxies. In this scenario, it is likely that a
substantial fraction of active galactic nuclei harbour a supermassive binary,
fueled by an accretion disk. These binaries would certainly be among the
strongest sources of sinusoidal gravitational waves. We investigate their
evolution considering, simultaneously, the accretion of the black hole's masses
from the disk, and the gravitational waves emitted during the orbital motion.
We also consider other astrophysical scenarios involving a coalescing binary
with non constant masses.
