Subdominant Modes of Scalar Superradiant Instability and Gravitational Wave Beats

Understand

Ultralight scalars could extract energy and angular momentum from a Kerr black hole (BH) because of superradiant instability.

• Multiple modes labelled with $nlm$ grow while rotating around the BH, emitting continuous gravitational wave (GW).
• In this work, we carefully study the contribution of the subdominant modes with $n\geq 1$ in the evolution of the BH-condensate system.
• We find the BH still evolves along the Regge trajectory of the $n=0$ modes even with the presence of the subdominant modes.