Initial Configuration

Black Hole Binary

The initial binary is in a quasiequilibrium circular orbit, and has an orbital angular frequency of $M\Omega \sim 0.0171$. The gravitational field variables are determined by using the puncture formalism. The ADM mass M of the binary is arbitrary. The black holes are nonspinning. The mass ratio of the binary is $q=36:29$.

Gaseous Disk

The initial gaseous disk obeys a polytropic equation of state, $P=K\rho^\Gamma_0$, at $t=0$. It is evolved according to the ideal gas law $P=(\Gamma-1)\rho_0\epsilon$, where P is the pressure, K is the polytropic gas constant, ε is the internal specific energy, Γ is the adiabatic index, and ρ0 the rest-mass density. We chose Γ = 4/3, appropriate for radiation pressure-dominated, thermal disks, which are typically optically thick. The initial disk satisfies the profile of a disk that would be in equilibrium about a single black hole with the same mass as the binary.

We seed the initial disk with a small, purely poloidal B-field. Note that the goal of our work is to assess how the final relaxed state of the disk depends on the binary mass ratio.