The ultralight boson is one of the potential candidates for dark matter. If it exists, it can be generated by a rapidly rotating black hole via superradiance, extracting the energy and angular momentum of the black hole and forming a boson cloud. The boson cloud can be affected by the presence of a companion star, generating rich dynamical effects and producing characteristic gravitational wave signals. During the inspiral of two black holes, the cloud carried with these black holes will redistribute among them and form the so-called black hole molecule. With the framework developed in this work, we analyze the evolution of this black hole molecule and found that bosons occupying the growing modes of the primary black hole can jump to the decaying modes of the companion black hole, resulting in cloud depletion. This mechanism of cloud depletion is different from that induced by the tidal perturbation from the companion.

• Received 13 October 2023
• Accepted 22 April 2024

DOI:https://doi.org/10.1103/PhysRevD.109.104046