  We consider the accretion of dark energy by constituent black holes in binary
formations during the present epoch of the Universe. In the context of an
observationally consistent dark energy model, we evaluate the growth of black
holes' masses due to accretion. We show that accretion leads to faster
circularization of the binary orbits. We compute the average power of the
gravitational waves emitted from binaries, which exhibits a considerable
enhancement due to the effect of growth of masses as a result of accretion.
This in turn, leads to a significant reduction of the coalescence time of the
binaries. We present examples pertaining to various choices of the initial
masses of the black holes in the stellar mass range and above, in order to
clearly establish a possible observational signature of dark energy in the
emerging era of gravitational wave astronomy.
