Evolution and detection of vector superradiant instabilities

TL;DR

This paper investigates the evolution of black hole-vector condensate systems due to superradiant instabilities, providing formulas for timescales and masses, and predicts observable gravitational wave signatures and constraints on vector masses from current data.

Contribution

It offers a detailed numerical study of multi-mode superradiant evolution and introduces formulas for key system parameters, enhancing understanding of black hole-vector field interactions.

Findings

Gravitational wave beat signatures from multi-mode superradiance could be observed.

Current black hole data constrains vector masses to specific ranges.

Formulas for timescales and maximum masses improve modeling of black hole superradiance.

Abstract

Ultralight vectors can extract energy and angular momentum from a Kerr black hole (BH) due to superradiant instability, resulting in the formation of a BH-condensate system. In this work, we carefully investigate the evolution of this system numerically with multiple superradiant modes. Simple formulas are obtained to estimate important timescales, maximum masses of different modes, as well as the BH mass and spin at various times. Due to the coexistence of modes with small frequency differences, the BH-condensate system emits gravitational waves with a unique beat signature, which could be directly observed by current and projected interferometers. Besides, the current BH spin-mass data from the binary BH merger events already exclude the vector mass in the range $5\times 10^{-15}\ \mathrm{eV} <\mu< 9\times 10^{-12}\ \mathrm{eV}$.