Plunge-merger-ringdown tests of general relativity with GW250114

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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mo stretchy="false">(</a:mo> <a:mo>ℓ</a:mo> <a:mo>,</a:mo> <a:mo stretchy="false">|</a:mo> <a:mi>m</a:mi> <a:mo stretchy="false">|</a:mo> <a:mo stretchy="false">)</a:mo> <a:mo>=</a:mo> <a:mo stretchy="false">(</a:mo> <a:mn>2</a:mn> <a:mo>,</a:mo> <a:mn>2</a:mn> <a:mo stretchy="false">)</a:mo> </a:math> mode are constrained to about 10% and 4%, respectively, at 90% credible level. These constraints are, respectively, 2 and 4 times more stringent than those obtained by analyzing GW150914. We also constrain, for the first time, the instantaneous frequency of the <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"> <i:mo stretchy="false">(</i:mo> <i:mo>ℓ</i:mo> <i:mo>,</i:mo> <i:mo stretchy="false">|</i:mo> <i:mi>m</i:mi> <i:mo stretchy="false">|</i:mo> <i:mo stretchy="false">)</i:mo> <i:mo>=</i:mo> <i:mo stretchy="false">(</i:mo> <i:mn>4</i:mn> <i:mo>,</i:mo> <i:mn>4</i:mn> <i:mo stretchy="false">)</i:mo> </i:math> mode at merger to about 6% and the time at which the gravitational-wave amplitude peaks to about 5 ms. These results provide exquisitely precise tests of general relativity in the strong-gravity regime and can be employed to constrain extensions of Einstein’s theory.