2018MNRAS.479.1569W

We study how stellar binaries interact with supermassive black hole binaries (SMBHBs) and we focus on double tidal disruption events (DTDEs), in which two stars in a binary are tidally disrupted in sequence by either of two supermassive black holes (SMBHs). According to our scattering experiments, we find that the time interval between two successive tidal disruption events (TDEs) depends on the semimajor axis of stellar binaries when they encounter the first SMBH. For a representative stellar binary with each star of 1 M_☉ and the semimajor axis less than 100 au, the maximum time interval is ∼150 d when the stellar binary is disrupted by a single SMBH. However, in the case of a SMBHB, the time interval is in the range from minutes to ten thousand years. DTDEs with a time interval larger than 150 d are called long time interval DTDEs (LDTDEs). The rate of DTDEs increases with the mass ratio of the SMBHB (q_bhb), and tends to be constant when q_bhb >= 0.1. The LDTDEs of the SMBHB can also be considered as two separate TDEs of the single SMBH, but this probability can be neglected, when the LDTDEs occur in the range of 150 d to 15 yr for a SMBHB with q_bhb >= 0.1. As in gas-poor galaxies, SMBHs are generally in a quiescent state, so we find that LDTDEs in the range of 150 d to 15 yr could be a useful tool for finding SMBHB candidates with q_bhb >= 0.1 at galactic centers.