Abstract Details

Name: Shashank Dattathri
Affiliation: Indian Institute of Science
Conference ID: ASI2021_59
Title : Stellar Capture Rates in Galactic Nuclei Containing a Supermassive Binary Black Hole
Authors and Co-Authors : Shashank Dattathri (Indian Institute of Science), Arun Mangalam (Indian Institute of Astrophysics)
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : We study the stellar capture rates in galactic nuclei containing a supermassive binary black hole with a primary supermassive black hole (SMBH), secondary SMBH, and field stars in a power-law cusp around the primary, representative of the late stages of a galaxy merger. The secondary black hole inspirals toward the center, at first due to dynamical friction, and later due to three-body effects. There is a short period of time during the binary evolution when the field stars exhibit angular momentum oscillations, that include the Lidov-Kozai mechanism, general relativistic effects, and stellar cusp precession. These oscillations can significantly increase the feeding into the loss cone. Our results show that the capture rate enters an enhanced phase with a peak of order 0.01/yr when the binary separation is about 0.1-1 pc, which is at least two orders of magnitude higher than isolated SMBH capture rates. The dependence of the peak rate and the enhanced phase's duration on the mass of the primary SMBH, the mass ratio, and the power-law index of the stellar cusp are presented. Enhanced tidal disruption event (TDE) rates in galactic nuclei can be used as a method to identify minor mergers. Multiple TDEs originating in a nucleus observed during a survey, like the LSST, indicate the possibility of a binary black hole.