Efficient Merger of Binary Supermassive Black Holes in Nonaxisymmetric Galaxies

Abstract

Binary supermassive black holes form naturally in galaxy mergers, but their\nlong-term evolution is uncertain. In spherical galaxies, N-body simulations\nshow that binary evolution stalls at separations much too large for significant\nemission of gravitational waves (the "final parsec problem"). Here, we follow\nthe long-term evolution of a massive binary in more realistic, triaxial and\nrotating galaxy models. We find that the binary does not stall. The binary\nhardening rates that we observe are sufficient to allow complete coalescence of\nbinary SBHs in 10 Gyr or less, even in the absence of collisional loss-cone\nrefilling or gas-dynamical torques, thus providing a potential solution to the\nfinal parsec problem.\n