Impact of Self-Interactions on Dark Matter Dynamics Near Binary Black Holes

Recent research by Josu C. Aurrekoetxea, James Marsden, Katy Clough, and Pedro G. Ferreira explores the dynamics of self-interacting scalar dark matter in the vicinity of binary black holes. The study, titled "Self-interacting scalar dark matter around binary black holes," utilizes numerical relativity simulations to analyze how dark matter clouds interact with isolated and binary black holes.

The findings indicate that self-interactions among dark matter can significantly influence the structure and behavior of these clouds. Specifically, the research identifies two types of interactions: repulsive and attractive. Repulsive self-interactions tend to smoothen the density spike around an isolated black hole, effectively saturating the density of the dark matter cloud. In contrast, attractive self-interactions can lead to more concentrated profiles but may also cause instability, resulting in phenomena similar to superradiant bosenova explosions, which can reduce the local density of the cloud.

Moreover, the study quantifies the impact of these self-interactions on gravitational wave signals during equal-mass black hole mergers. The researchers found that repulsive interactions can decrease the dephasing of the gravitational wave signal, while attractive interactions may increase it, particularly if they dominate before the merger. This research provides critical insights into the role of dark matter in the dynamics of black hole systems and could enhance our understanding of gravitational wave observations.

The full paper can be accessed at arXiv:2409.01937.