We investigate the imprints of accretion and dynamical friction on the gravitational-wave signals emitted by binary black holes embedded in a scalar dark matter cloud. As a key feature in this work, we focus on scalar fields with a repulsive self-interaction that balances against the self-gravity of the cloud. To a first approximation, the phase of the gravitational-wave signal receives extra correction terms at −3PN, −4PN and −5.5PN orders, relative to the prediction of vacuum general relativity, due to cloud gravity, accretion and dynamical friction. Future observations by LISA and B-DECIGO have the potential to detect these effects for a large range of scalar masses~mDM and self-interaction couplings~λ4. This would correspond to scenarios with dark matter clouds smaller than 0.1 pc, which would be difficult to detect by other probes.
@article{arxiv.2305.18540,
title = {Gravitational waves from binary black holes in a self-interacting scalar dark matter cloud},
author = {Alexis Boudon and Philippe Brax and Patrick Valageas and Leong Khim Wong},
journal= {arXiv preprint arXiv:2305.18540},
year = {2025}
}