Effect of an Accretion Disk on the Gravitational Wave Signal from an   Inspiralling Binary
  Since black holes can only accrete sub-Keplerian matter, a companion black hole orbiting on a circular and instantaneously Keplerian orbit around a central, massive black hole in a galactic Centre will loss angular momentum and energy to the accreting matter. This loss could be a significant fraction of the loss due to gravitational wave (GW) emission. The corresponding GW signal would be modified. We discuss this effects in the light of the modern accretion disk theory. 
Sandip K. Chakrabarti (SNBNCBS and CSP)