Double tidal disruption events with supermassive black hole binaries

The two stars of stellar binaries can be tidally disrupted by supermassive black holes (SMBHs) or supermassive black hole binaries (SMBHBs) in sequence. In this contribution, we review our recent study about double tidal disruption events (DTDEs) with SMBHBs. With the help of scattering experiments, we find that the time interval between two successive tidal disruption events (TDEs) depend on the semimajor axis of incident stellar binaries. For stellar binaries with 1 M⊙ for each companion star and a semimajor axis less than 100 au, the maximum time interval is about 150 days when the stellar binary is tidally disrupted by an SMBH. However, for an SMBHB, the time intervals can be very large, and the maximum can exceed 10,000 years. Moreover, we also compare the probabilities of a DTDE with the time interval larger than 150 days by the SMBHB and of two separate TDEs by the SMBH with the same time interval. We find that, for the time interval of 150 days to 15 years, the probability of DTDEs by the SMBHB with a large mass ratio (i.e., qbhb ≳ 0.1) is larger than that of the SMBH scenario. Finally, according to our results, we suggest that DTDEs with the time interval of 150 days to 15 years could be useful tools for finding SMBHB candidates with the mass ratio qbhb ≳ 0.1 at galactic centers.