The first informative astrophysical calibration of gravitational-wave detectors is reported using GW240925 and GW250207.
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GWTC-4.0: Tests of General Relativity. III. Tests of the Remnants
Canonical reference. 83% of citing Pith papers cite this work as background.
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This is the third paper of the set recording the results of the suite of tests of general relativity (GR) performed on the signals from the fourth Gravitational-Wave Transient Catalog (GWTC-4.0), where we focus on the remnants of the binary mergers. We examine for the first time 42 events from the first part of the fourth observing run of the LIGO-Virgo-KAGRA detectors, alongside events from the previous observation runs, restricting our analysis to the confident signals, which were measured in at least two detectors and that have false alarm rates $\le 10^{-3} \mathrm{yr}^{-1}$. This paper focuses on seven tests of the coalescence remnants. Three of these are tests of the ringdown and its consistency with the expected quasinormal mode spectrum of a Kerr black hole. Specifically, two tests analyze just the ringdown in the time domain, and the third test analyzes the entire signal in the frequency domain. Four tests allow for the existence of possible echoes arriving after the end of the ringdown, which are not expected in GR. We find overall consistency of the remnants with GR. When combining events by multiplying likelihoods (hierarchically), one analysis finds that the GR prediction lies at the boundary of the $98.6^{+1.4}_{-9.4}\%$ ($99.3^{+0.7}_{-4.5}\%$) credible region, an increase from $93.8^{+6.1}_{-20.0}\%$ ($94.9^{+4.4}_{-18.2}\%$) for GWTC-3.0. Here the ranges of values comes from bootstrapping to account for the finite number of events analyzed and suggest that some of the apparently significant deviation could be attributed to variance due to the finite catalog. Since the significance also decreases to 92.2% (96.2%) when including the more recent very loud event GW250114, there is no strong evidence for a GR deviation. We find no evidence for post-merger echoes in the events that were analyzed. (Abridged)
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Numerical relativity simulations of black hole scattering in Einstein-scalar-Gauss-Bonnet gravity agree closely with effective-one-body analytic predictions.
A first-principles energy-function calculation determines the quartic coefficient b0 whose sign sets the order of the spontaneous-scalarization phase transition in scalar-tensor neutron stars.
Direct waves in filtered Schwarzschild ringdown are the anti-causal filter-pole contribution sourced by near-horizon trajectory dynamics and do not vanish.
A gravitational-wave method infers the Kerr-equivalent horizon area from direct waves in the near-merger signal of GW250114, yielding consistency with the Kerr remnant and a new test of Hawking's area law.
An external dynamical environment forms a resonant cavity with a black hole in dCS gravity that triggers Mathieu instability in the scalar sector, producing cascading amplification of gravitational waves via a delayed secondary burst.
In massive scalar-tensor gravity, rotating neutron stars that collapse emit nearly the same tensor gravitational waves as in general relativity, but lose about 10^-3 solar masses of energy in scalar radiation - far more than the quadrupole channel.
Gravitational electric-magnetic duality at the light ring organizes and preserves quasinormal mode isospectrality in GR and selects duality-invariant higher-derivative corrections in effective field theories.
For a loud stellar-mass black hole binary, adding realistic orbital eccentricity to multiband Bayesian analysis weakens dipole-radiation constraints to |b|≲10⁻⁷, with strong degeneracies among dipole strength, chirp mass, and eccentricity.
Numerical simulations of equal-mass boson-star mergers reveal larger waveform deviations from black-hole binaries in late inspiral and merger, plus odd multipole excitations for certain scalar-field phases, with some signals degenerate until IMR consistency tests are applied.
Polynomial models for the (2,2) post-merger waveform amplitudes of eccentric non-spinning binary black holes are constructed from numerical-relativity data as functions of symmetric mass ratio and two merger-time dynamical parameters.
GreyRing model based on greybody factors reproduces numerical relativity ringdown signals with mismatches of order 10^{-6} and enables a new post-merger consistency test of general relativity applied to GW250114.
Leading-order deviations from general relativity in scalar quasinormal modes of rotating black holes are computed numerically up to dimensionless spins of 0.99 in quadratic-curvature scalar-tensor theories.
In shift-symmetric Horndeski gravity, scalar field QNM contamination of black hole ringdowns appears at the same perturbative order as frequency shifts, and can dominate them if scalar amplitude suppression is relaxed.
A mixture-model framework for combining gravitational-wave tests of General Relativity yields Bayes factors of 10-20 favoring GR, substantially lower than existing methods that assume uniform deviations across events.
Numerical relativity in the decoupling limit reveals dynamical scalarization and spin-induced (de)scalarization during hyperbolic black hole encounters for both signs of the coupling.
Bayesian analysis finds individual QNM frequencies near avoided crossings hard to resolve even under optimistic conditions, though collective AC waveform signatures may remain detectable if those modes dominate and slower-mode contamination is minimal.
An EFT consistency map transports cosmology-conditioned posteriors from scalar-tensor FLRW backgrounds to black-hole quasinormal-mode kernels, showing tensor-speed effects fall below ringdown detectability while other operators remain potentially active near black holes.
Adding the electromagnetic polarization-angle prior to a PPE test of GW170817 tightens the scalar-breathing amplitude bound by ~60% and yields a non-significant ~2–3σ preference for a scalar mode.
Causal viscous relativistic hydrodynamics applied to neutron stars yields new axial mode families without perfect-fluid counterparts, including mode avoidance and long-lived modes.
Bilinear products for black hole quasinormal modes on hyperboloidal foliations are divergent due to CPT transformations but can be regularized to define orthogonal modes and excitation coefficients.
Leading-order cubic-curvature corrections to scalar quasinormal modes of black holes with spins up to 0.99M are computed numerically for modes up to l=5 with relative errors below 10^{-4}.
Third-generation gravitational-wave detectors can constrain frequency-dependent beyond-GR waveform modifications in the stochastic background, but modified propagation effects remain degenerate with astrophysical population parameters.
An idealized Gaussian model demonstrates that single-event correlations inflate uncertainties in population correlations and that catalog-wide correlated biases can be misread as population correlations.
citing papers explorer
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GW240925 and GW250207: Astrophysical Calibration of Gravitational-wave Detectors
The first informative astrophysical calibration of gravitational-wave detectors is reported using GW240925 and GW250207.
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Black-Hole Scattering in Einstein-scalar-Gauss-Bonnet: Numerical Relativity Meets Analytics
Numerical relativity simulations of black hole scattering in Einstein-scalar-Gauss-Bonnet gravity agree closely with effective-one-body analytic predictions.
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Underlying mechanisms of phase transitions in scalar-tensor theories
A first-principles energy-function calculation determines the quartic coefficient b0 whose sign sets the order of the spontaneous-scalarization phase transition in scalar-tensor neutron stars.
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Foundations of Direct Waves in Schwarzschild Ringdown
Direct waves in filtered Schwarzschild ringdown are the anti-causal filter-pole contribution sourced by near-horizon trajectory dynamics and do not vanish.
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Measuring a Black Hole's Area Immediately after Merger: A Direct-Wave Test of Hawking's Area Law
A gravitational-wave method infers the Kerr-equivalent horizon area from direct waves in the near-merger signal of GW250114, yielding consistency with the Kerr remnant and a new test of Hawking's area law.
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Cascading amplification of gravitational waves triggered by environment in dynamical Chern-Simons gravity
An external dynamical environment forms a resonant cavity with a black hole in dCS gravity that triggers Mathieu instability in the scalar sector, producing cascading amplification of gravitational waves via a delayed secondary burst.
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Rapidly Rotating Neutron Star Collapse in Massive Scalar-Tensor Theories
In massive scalar-tensor gravity, rotating neutron stars that collapse emit nearly the same tensor gravitational waves as in general relativity, but lose about 10^-3 solar masses of energy in scalar radiation - far more than the quadrupole channel.
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Gravitational electric-magnetic duality at the light ring and quasinormal mode isospectrality in effective field theories
Gravitational electric-magnetic duality at the light ring organizes and preserves quasinormal mode isospectrality in GR and selects duality-invariant higher-derivative corrections in effective field theories.
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Constraining Dipole Radiation with Multiband Gravitational Waves from Eccentric Binary Black Holes
For a loud stellar-mass black hole binary, adding realistic orbital eccentricity to multiband Bayesian analysis weakens dipole-radiation constraints to |b|≲10⁻⁷, with strong degeneracies among dipole strength, chirp mass, and eccentricity.
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Lessons from binary dynamics of inspiralling equal-mass boson-star mergers
Numerical simulations of equal-mass boson-star mergers reveal larger waveform deviations from black-hole binaries in late inspiral and merger, plus odd multipole excitations for certain scalar-field phases, with some signals degenerate until IMR consistency tests are applied.
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Highly eccentric non-spinning binary black hole mergers: quadrupolar post-merger waveforms
Polynomial models for the (2,2) post-merger waveform amplitudes of eccentric non-spinning binary black holes are constructed from numerical-relativity data as functions of symmetric mass ratio and two merger-time dynamical parameters.
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Novel ringdown tests of general relativity with black hole greybody factors
GreyRing model based on greybody factors reproduces numerical relativity ringdown signals with mismatches of order 10^{-6} and enables a new post-merger consistency test of general relativity applied to GW250114.
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Quadratic gravity corrections to scalar QNMs of rapidly rotating black holes
Leading-order deviations from general relativity in scalar quasinormal modes of rotating black holes are computed numerically up to dimensionless spins of 0.99 in quadratic-curvature scalar-tensor theories.
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Beyond black hole spectroscopy: Quasinormal mode contamination by massless scalars
In shift-symmetric Horndeski gravity, scalar field QNM contamination of black hole ringdowns appears at the same perturbative order as frequency shifts, and can dominate them if scalar amplitude suppression is relaxed.
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Testing General Relativity with GWTC-4.0 through mixture models
A mixture-model framework for combining gravitational-wave tests of General Relativity yields Bayes factors of 10-20 favoring GR, substantially lower than existing methods that assume uniform deviations across events.
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Scalarization and descalarization in hyperbolic encounters of black holes
Numerical relativity in the decoupling limit reveals dynamical scalarization and spin-induced (de)scalarization during hyperbolic black hole encounters for both signs of the coupling.
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Detectability of avoided crossings in black hole ringdowns
Bayesian analysis finds individual QNM frequencies near avoided crossings hard to resolve even under optimistic conditions, though collective AC waveform signatures may remain detectable if those modes dominate and slower-mode contamination is minimal.
-
A cosmology-to-ringdown EFT consistency map for scalar-tensor gravity
An EFT consistency map transports cosmology-conditioned posteriors from scalar-tensor FLRW backgrounds to black-hole quasinormal-mode kernels, showing tensor-speed effects fall below ringdown detectability while other operators remain potentially active near black holes.
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Tests of scalar polarizations with multi-messenger events
Adding the electromagnetic polarization-angle prior to a PPE test of GW170817 tightens the scalar-breathing amplitude bound by ~60% and yields a non-significant ~2–3σ preference for a scalar mode.
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Axial Oscillations of Viscous Neutron Stars
Causal viscous relativistic hydrodynamics applied to neutron stars yields new axial mode families without perfect-fluid counterparts, including mode avoidance and long-lived modes.
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Bilinear products and the orthogonality of quasinormal modes on hyperboloidal foliations
Bilinear products for black hole quasinormal modes on hyperboloidal foliations are divergent due to CPT transformations but can be regularized to define orthogonal modes and excitation coefficients.
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Ringing of rapidly rotating black holes in effective field theory
Leading-order cubic-curvature corrections to scalar quasinormal modes of black holes with spins up to 0.99M are computed numerically for modes up to l=5 with relative errors below 10^{-4}.
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Modeling Uncertainties in Modified Gravity Predictions for the Stochastic Gravitational-Wave Background
Third-generation gravitational-wave detectors can constrain frequency-dependent beyond-GR waveform modifications in the stochastic background, but modified propagation effects remain degenerate with astrophysical population parameters.
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Population-level correlations in Bayesian statistics: an illustrative model for gravitational-wave astronomy
An idealized Gaussian model demonstrates that single-event correlations inflate uncertainties in population correlations and that catalog-wide correlated biases can be misread as population correlations.
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Constraining Gravitational Wave Memory with Hierarchical Inference
Hierarchical Bayesian inference on GWTC-5.0 constrains the memory enhancement factor to 0.26 with large uncertainties consistent with the GR value of 1 and forecasts that 2000 detections are needed for a 1σ constraint away from zero.
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Probing (sub-)solar-mass black holes and superspinars with current and next-generation gravitational-wave observatories
Using TaylorF2 post-Newtonian waveforms truncated at ISCO, the study finds that Einstein Telescope and Cosmic Explorer can reach SNR of 100-350 and measure primary spin to 10^{-4}-10^{-3} precision for 0.1-2 solar mass exotic compact objects.
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Ringdown Analysis of GW250114 with Orthonormal Modes
Orthonormal QNM analysis of GW250114 raises the significance of the first overtone of the ℓ=m=2 mode from 82.5% to 99.9% and detects no significant deviation from Kerr predictions.
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Prompt Response from Plunging Sources in Schwarzschild Spacetime
The prompt response is ~1.2 times stronger than quasinormal mode excitation during inspiral and enables 99% accurate reconstruction of the full inspiral-merger-ringdown waveform when combined with other components.
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Environmental effects vs. modified gravity in the LISA massive black hole binary population
Population-level hierarchical analysis shows environmental effects from circumbinary disks are unlikely to bias LISA tests of general relativity for massive black hole binaries in realistic scenarios.
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Modeling Direct Waves in Binary Black Hole Ringdowns
Direct waves are identified in NR ringdown waveforms using QNM extraction techniques over a range of start times, but their frequency deviates from the horizon-mode prediction.
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Mitigating Systematic Errors in Parameter Estimation of Binary Black Hole Mergers in O1-O3 LIGO-Virgo Data
Reanalysis of flagged LVK events with waveform uncertainty models produces consistent spin and precession inferences across raw/deglitched data and multiple waveform approximants.
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Improved Constraints on Non-Kerr Deviations from Binary Black Hole Inspirals Using GWTC-4 Data
GWTC-4 inspirals yield tighter constraints on Johannsen parameters α13 and ε3, both consistent with zero and thus with the Kerr geometry.