The imprint of superradiance on hierarchical black hole mergers

Understand

Ultralight bosons are a proposed solution to outstanding problems in cosmology and particle physics: they provide a dark-matter candidate while potentially explaining the strong charge-parity problem.

• If they exist, ultralight bosons can interact with black holes through the superradiant instability.
• In this work we explore the consequences of this instability on the evolution of hierarchical black holes within dense stellar clusters.
• By reducing the spin of individual black holes, superradiance reduce the recoil velocity of merging binary black holes, which, in turn, increases the retention fraction of hierarchical merger remnants.