Abstract
The gravitational wave strain emitted by a perturbed black hole (BH) ringing down is typically modeled analytically using first-order BH perturbation theory. In this Letter, we show that second-order effects are necessary for modeling ringdowns from BH merger simulations. Focusing on the strain’s angular harmonic, we show the presence of a quadratic effect across a range of binary BH mass ratios that agrees with theoretical expectations. We find that the quadratic mode’s amplitude exhibits quadratic scaling with the fundamental mode—its parent mode. The nonlinear mode’s amplitude is comparable to or even larger than that of the linear mode. Therefore, correctly modeling the ringdown of higher harmonics—improving mode mismatches by up to 2 orders of magnitude—requires the inclusion of nonlinear effects.
- Received 26 August 2022
- Revised 8 November 2022
- Accepted 15 December 2022
DOI:https://doi.org/10.1103/PhysRevLett.130.081402
© 2023 American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Finding Nonlinearities in Black Hole Ringdowns
Published 22 February 2023
Simulations show that nonlinear spacetime dynamics manifest in the postmerger gravitational-wave signal of binary black hole coalescence.
See more in Physics