Circumbinary Disk Dynamics

We will present the results of numerical simulations of a binary black hole surrounded by a thin, massless, locally isothermal, viscous accretion disk. We describe the numerical setup of these time-dependent simulations, and investigate the evolution of the fluid in the presence of the gravitational potential generated by the binary. We have investigated a series of configurations characterized by different mass ratios and inclinations of the disk with respect to the binary's orbit. We analyze the properties of the density distribution, such as the location of the maximum, size of the central gap, etc., as a function of our model parameters. Furthermore, calculating pressure and velocity of the fluid, we can characterize additional properties of the fluid flow, such as the azimuthal propagation of angular momentum, dynamical and viscous torque balance, accretion rate, luminosity, stability, etc. Having in mind the recent active research in the field of electromagnetic searches for supermassive black-hole binaries, and the eventual searches for gravitational waves from these same sources, we present findings which are the most relevant for these two domains of astrophysics.