Yes, dynamical friction can "quickly" (on the order of 100 Myr) bring the two black holes to a distance of ~1 pc to each other. Gravitational wave radiation ca

Yes, dynamical friction can "quickly" (on the order of 100 Myr) bring the two black holes to a distance of ~1 pc to each other. Gravitational wave radiation can "quickly" cause a merger if they are within a bit less than ~0.1 pc of each other. But how they go from 1 to 0.1 pc on a timescale of ~100 Myr is unknown.