# Modified evolution of stellar binaries from supermassive black hole binaries

## TL;DR

This paper investigates how the presence of a second supermassive black hole influences the evolution, mergers, and tidal disruption events of stellar binaries at galactic centers, revealing significant effects on merger rates and TDEs.

## Contribution

It provides an analytical and numerical study of stellar binary dynamics perturbed by a distant SMBH binary, highlighting the impact on merger and TDE rates, which was not thoroughly explored before.

## Key findings

- Approximately 70% of stellar binaries merge due to Lidov-Kozai oscillations.
- Tidal disruption events occur in about 10% of cases, especially with inclined outer orbits.
- External SMBH binaries significantly increase TDE rates compared to single SMBH scenarios.

## Abstract

The evolution of main sequence binaries resided in the galactic centre is influenced a lot by the central super massive black hole (SMBH). Due to this perturbation, the stars in a dense environment are likely to experience mergers or collisions through secular or non-secular interactions. In this work, we study the dynamics of the stellar binaries at galactic center, perturbed by another distant SMBH. Geometrically, such a four-body system is supposed to be decomposed into the inner triple (SMBH-star-star) and the outer triple (SMBH-stellar binary-SMBH). We survey the parameter space and determine the criteria analytically for the stellar mergers and the tidal disruption events (TDEs). For a relative distant and equal masses SMBH binary, the stars have more opportunities to merge as a result from the Lidov-Kozai(LK) oscillations in the inner triple. With a sample of tight stellar binaries, our numerical experiments reveal that a significant fraction of the binaries, ~70 per cent, experience merger eventually. Whereas the majority of the stellar TDEs are likely to occur at a close periapses to the SMBH, induced by the outer Kozai effect. The tidal disruptions are found numerically as many as ~10 per cent for a close SMBH binary that is enhanced significantly than the one without the external SMBH. These effects require the outer perturber to have an inclined orbit (>=40 degree) relatively to the inner orbital plane and may lead to a burst of the extremely astronomical events associated with the detection of the SMBH binary.