Self-interacting scalar dark matter around binary black holes

Understand

Gravitational waves can provide crucial insights about the environments in which black holes live.

• In this work, we use numerical relativity simulations to study the behaviour of self-interacting scalar (wave-like) dark matter clouds accreting onto isolated and binary black holes.
• We find that repulsive self-interactions smoothen the ``spike'' of an isolated black hole and saturate the density.
• Attractive self-interactions enhance the growth and result in more cuspy profiles, but can become unstable and undergo explosions akin to the superradiant bosenova that reduce the local cloud density.