Massive black hole pairs in clumpy, self-gravitating circumnuclear disks: stochastic orbital decay

Understand

We study the dynamics of massive black hole pairs in clumpy gaseous circumnuclear disks.

• We track the orbital decay of the light, secondary black hole $M_{\bullet2}$ orbiting around the more massive primary at the center of the disk, using $N$-body/smoothed particle hydrodynamic simulations.
• We find that the gravitational interaction of $M_{\bullet2}$ with massive clumps $M_{\rm cl}$ erratically perturbs the otherwise smooth orbital decay.
• In close encounters with massive clumps, gravitational slingshots can kick the secondary black hole out of the disk plane.