Ringdown of a postinnermost stable circular orbit of a rapidly spinning black hole: Mass ratio dependence of higher harmonic quasinormal mode excitation
arXiv:2408.16747 · doi:10.1103/PhysRevD.110.124029
Abstract
In a binary merger with a small mass ratio, as the secondary body approaches the innermost stable circular orbit (ISCO) of the primary black hole, the motion transitions from the adiabatic inspiral to the plunge governed by the geodesic equation. The plunge orbit is expected to excite the ringdown gravitational wave, which encodes information about the primary black hole's geometry. The details of the transition regime depend on the binary's mass ratio through radiation fluxes, which in turn influence the initial conditions for the plunge. As such, the mass ratio affects the post-ISCO ringdown gravitational wave excitation. In this study, we numerically investigate the mass ratio dependence of higher harmonic quasi-normal mode excitations in the post-ISCO gravitational waves of rapidly spinning black holes, based on the Teukolsky-Sasaki-Nakamura formalism. We consider the effect of mass ratio on the gravitational waves by accounting for the energy and angular momentum losses during the transition regime following the Ori-Thorne procedure. We examine two mass ratio scenarios: the intermediate mass ratio (IMR) and the extreme mass ratio (EMR). Our main finding is that higher harmonic quasi-normal modes are significantly excited in an IMR merger involving a highly spinning primary black hole. This implies that detecting an IMR merger involving such a primary black hole with space-based gravitational wave interferometers can provide valuable opportunities to infer black hole properties or test general relativity with excellent precision.
22 pages, 12 figures, v2: matches the published version
References in corpus (10)
- Agnostic black hole spectroscopy: Quasinormal mode content of numerical relativity waveforms and limits of validity of linear perturbation theory
- Gravitational perturbations of the Kerr geometry: High-accuracy study
- qnm: A Python package for calculating Kerr quasinormal modes, separation constants, and spherical-spheroidal mixing coefficients
- Binary black hole merger gravitational waves and recoil in the large mass ratio limit
- Gravity Waves from Extreme-Mass-Ratio Plunges into Kerr Black Holes
- Thermal Ringdown of a Kerr Black Hole: Overtone Excitation, Fermi-Dirac Statistics and Greybody Factor
- Transition from adiabatic inspiral to plunge into a spinning black hole
- Self-force framework for transition-to-plunge waveforms
- Iterative extraction of overtones from black hole ringdown
- Slowly Decaying Ringdown of a Rapidly Spinning Black Hole: Probing the No-Hair Theorem by Small Mass-Ratio Mergers with LISA