  In a recent paper we have shown that the evolution of a misaligned disc
around a spinning black hole can result in tearing the disc into many distinct
planes. Tearing discs with random orientations produce direct dynamical
accretion on to the hole in approximately 70% of all cases. Here we examine the
evolution of a misaligned disc around a binary system. We show that these discs
are susceptible to tearing for almost all inclinations. We also show that
tearing of the disc can result in a significant acceleration of the disc
evolution and subsequent accretion on to the binary - by factors up to 10,000
times that of a coplanar prograde disc with otherwise identical parameters.
This provides a promising mechanism for driving mergers of supermassive black
hole (SMBH) binaries on timescales much shorter than a Hubble time. Disc
tearing also suggests new observational signatures of accreting SMBH binaries,
and other systems such as protostellar binaries.
