Efficient Merger of Binary Supermassive Black Holes in Merging Galaxies

Understand

In spherical galaxies, binary supermassive black holes (SMBHs) have difficulty reaching sub-parsec separations due to depletion of stars on orbits that intersect the massive binary - the final-parsec problem.

• Galaxies that form via major mergers are substantially nonspherical, and it has been argued that the centrophilic orbits in triaxial galaxies might provide stars to the massive binary at a high enough rate to avoid stalling.
• Here we test that idea by carrying out fully self-consistent merger simulations of galaxies containing central SMBHs.
• We find hardening rates of the massive binaries that are indeed much higher than in spherical models, and essentially independent of the number of particles used in the simulations.