Plunge-Merger-Ringdown Tests of General Relativity with GW250114

Abstract

The binary black hole signal GW250114, the clearest gravitational wave detected to date, offers a unique opportunity to test general relativity in the relativistic strong-gravity regime. How well does GW250114 agree with Einstein's predictions in the plunge-merger-ringdown stage? To address this point, we constrain deviations from general relativity across the plunge-merger-ringdown stage of spin-precessing binaries with a parametrized waveform model within the effective-one-body formalism. We find that deviations from the peak gravitational-wave amplitude and instantaneous frequency of the $(\ell, |m|)=(2,2)$ mode are constrained to about $10\%$ and $4\%$, respectively, at $90\%$ credible level. These constraints are, respectively, two and four times more stringent than those obtained by analyzing GW150914. We also constrain, for the first time, the instantaneous frequency of the $(\ell, |m|)=(4,4)$ mode at merger to about $6\%$, and the time at which the gravitational-wave amplitude peaks to about $5~\mathrm{ms}$. These results are the most precise tests of general relativity in the nonlinear regime to date, and can be employed to constrain extensions of Einsten's theory.

Figures (9)

• Figure 1: The one-dimensional posterior distributions on the merger--ringdown deviation parameters for our analysis (blue lines) and the LVK analysis ligo2025black (red lines), which included only ringdown deviations. Both analyses were performed using the pSEOBNRv5PHM waveform model where the shaded areas indicate 90% credible intervals. The vertical lines mark the null GR expectation. The inferred values of $\delta A_{22}$ and $\delta\omega_{22}$ are consistent with GR.
• Figure 2: The one-dimensional posterior distributions on the merger parameters for GW250114, where the shaded areas indicate 90% credible intervals. The vertical lines mark the null GR expectation. The inferred values of $\delta A_{22}$ and $\delta \omega_{22}$ are consistent with GR, while $\delta \omega_{44}$ is marginally consistent with GR. The posterior distribution on $\delta A_{44}$ is unconstrained and rails against the upper bound (note the different scale with respect to the other parameters).
• Figure 3: The one-dimensional posterior distributions on the merger--ringdown deviation parameters for our analysis (blue lines) and the LVK analysis ligo2025black (red lines), which included only ringdown deviations. Both analyses were performed using the pSEOBNRv5PHM waveform model. The shaded areas indicate 90% credible intervals. The vertical lines mark the null GR expectation. We constrain for the first time the merger time shift to be consistent with GR.
• Figure 4: The one- and two-dimensional posterior distributions on the orbital eccentricity $e$ and the relativistic anomaly $\zeta$ obtained with the aligned-spin, eccentric SEOBNRv5EHM model Gamboa:2024hli. All contours indicate 90% credible regions. The eccentricity is constrained to $e < 0.025$ at 90% confidence, consistent with the bound $e < 0.03$ reported by the LVK collaboration LIGOScientific:2025rid.
• Figure 5: The one-dimensional posterior distributions on the merger--ringdown deviation parameters for our analysis (blue lines) and the LVK analysis ligo2025black (red lines), which considered only ringdown deviations. Both analyses were performed using the pSEOBNRv5PHM waveform model. The shaded areas indicate 90% credible intervals. The vertical lines mark the null GR expectation. The posterior distributions on the $(2,2,0)$ and $(4,4,0)$ QNM deviations are almost unchanged when the merger parameters are added to the analysis, providing evidence on the robustness of the LVK analysis on the $(4,4,0)$ QNM.