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Dynamics of a binary system around a supermassive black hole

Maeda, K-I and Gupta, P and Okawa, H (2023) Dynamics of a binary system around a supermassive black hole. In: Physical Review D, 107 (12).

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Official URL: https://doi.org/10.1103/PhysRevD.107.124039


We discuss the motion of a binary system around a supermassive black hole. Using Fermi-Walker transport, we construct a local inertial reference frame and set up a Newtonian binary system. Assuming a circular geodesic observer around a Schwarzschild black hole, we write down the equations of motion of a binary. Introducing a small acceleration of the observer, we remove the interaction terms between the center of mass (CM) of a binary and its relative coordinates. The CM follows the observer's orbit, but its motion deviates from an exact circular geodesic. We first solve the relative motion of a binary system, and then find the motion of the CM by the perturbation equations with the small acceleration. We show that von Zeipel-Lidov-Kozai (vZLK) oscillations appear when a binary is compact and the initial inclination is larger than a critical angle. In a hard binary system, vZLK oscillations are regular, whereas in a soft binary system, oscillations are irregular both in period and in amplitude, although stable. We find an orbital flip when the initial inclination is large. As for the motion of the CM, the radial deviations from a circular orbit become stable oscillations with very small amplitu

Item Type: Journal Article
Publication: Physical Review D
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the American Physical Society.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 25 Jul 2023 04:58
Last Modified: 25 Jul 2023 04:58
URI: https://eprints.iisc.ac.in/id/eprint/82582

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