Assisted Inspirals of Stellar Mass Black Holes Embedded in AGN Disks:
  Solving the "Final AU Problem"
  We explore the evolution of stellar mass black hole binaries (BHBs) which are
formed in the self-gravitating disks of active galactic nuclei (AGN). Hardening
due to three-body scattering and gaseous drag are effective mechanisms that
reduce the semi-major axis of a BHB to radii where gravitational waves take
over, on timescales shorter than the typical lifetime of the AGN disk. Taking
observationally-motivated assumptions for the rate of star formation in AGN
disks, we find a rate of disk-induced BHB mergers ($\mathcal{R} \sim 3~{\rm
yr}^{-1}~{\rm Gpc}^{-3}$, but with large uncertainties) that is comparable with
existing estimates of the field rate of BHB mergers, and the approximate BHB
merger rate implied by the recent Advanced LIGO detection of GW150914. BHBs
formed thorough this channel will frequently be associated with luminous AGN,
which are relatively rare within the sky error regions of future gravitational
wave detector arrays. This channel could also possess a (potentially transient)
electromagnetic counterpart due to super-Eddington accretion onto the stellar
mass black hole following the merger.
