Tidal disruption of stars in a supermassive black hole binary system: the influence of orbital properties on fallback and accretion rates

The disruption of a star by a supermassive black hole generates a sudden bright flare. Previous studies have focused on the disruption by single black holes, for which the fallback rate decays as alpha t(-5/3). In this paper, we generalize the study to the case of a supermassive black hole binary (SMBHB), using both analytical estimates and hydrodynamical simulations, looking for specific observable signatures. The range of binary separation for which it is possible to distinguish between the disruption created by a single or a binary black hole concerns typically separations of the order of a few milliparsecs for a primary of mass similar to 10(6) M-circle dot. When the fallback rate is affected by the secondary, it undergoes two types interruptions, depending on the initial inclination. of the orbit of the star relative to the plane of the SMBHB. For theta less than or similar to 70 degrees, periodic sharp interruptions occur and the time of first interruption depends on the distance of the secondary black hole with the debris. If theta greater than or similar to 70 degrees, a first smooth interruption occurs, but not always followed by a further recovery of the fallback rate. This implies that most of the TDEs around a SMBHB will undergo periodic sharp interruptions of their light curve.