Nonlinearities in Gravity: Gravitational Wave Ringdown

Abstract

The modeling of gravitational wave ringdown has traditionally relied on linear perturbation theory, which mainly describes the late-time behavior of a perturbed black hole after a binary merger. However, the need for more accurate ringdown models has motivated the understanding of nonlinear gravitational effects. In this paper, we summarize the main properties and latest developments of quadratic effects in ringdown models, which are expected to be detectable with next-generation gravitational wave detectors, and will allow for new consistency tests of general relativity.

Figures (3)

• Figure 1: Residual of the simulation for a GW150914-like event and two ringdown models: a purely linear model (red) and a model with QQNM (blue). Fig. from Mitman:2022qdl.
• Figure 2: Characteristic noise (black and gray lines) for ET and CE detectors, compared to characteristic strain (colored lines) of the individual QNMs for a GW150914-like GW event. Fig. from Lagos:2024ekd.
• Figure 3: Real and imaginary components of the QNM frequencies (in Hz) and their $1\sigma$ uncertainty, for a GW150914-like event at $z=0.045$ in ET. Left shows the errors when the QQNM is measured independently. Right shows the errors when the QQNM is used as a dependent mode (blue) and compares it to the independent case (black). Figs. from Lagos:2024ekd.