The first informative astrophysical calibration of gravitational-wave detectors is reported using GW240925 and GW250207.
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GWTC-2.1: Deep Extended Catalog of Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
Mixed citation behavior. Most common role is background (47%).
abstract
The second Gravitational-Wave Transient Catalog reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15:00 UTC and 1 October 2019 15:00 UTC. We present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the astrophysical probability for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have an astrophysical probability greater than 0.5. Of these candidates, 36 have been reported in GWTC-2. If the 8 additional high-significance candidates presented here are astrophysical, the mass range of events that are unambiguously identified as binary black holes (both objects $\geq 3M_\odot$) is increased compared to GWTC-2, with total masses from $\sim 14 M_\odot$ for GW190924_021846 to $\sim 182 M_\odot$ for GW190426_190642. The primary components of two new candidate events (GW190403_051519 and GW190426_190642) fall in the mass gap predicted by pair instability supernova theory. We also expand the population of binaries with significantly asymmetric mass ratios reported in GWTC-2 by an additional two events (the mass ratio is less than $0.65$ and $0.44$ at $90\%$ probability for GW190403_051519 and GW190917_114630 respectively), and find that 2 of the 8 new events have effective inspiral spins $\chi_\mathrm{eff} > 0$ (at $90\%$ credibility), while no binary is consistent with $\chi_\mathrm{eff} < 0$ at the same significance.
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representative citing papers
The first search for scalar-induced gravitational waves via pulsar parameter drifts yields f_PBH < 10^{-10} (95% CL) for PBH masses 0.3 to 4e4 solar masses, strongly disfavoring a primordial black hole origin for LVK binary black holes.
GW241011 data shows consistency with Kerr black holes for both quadrupole and octupole moments and delivers the first observational bounds on spin-induced octupole deviations.
First joint population inference on binary black hole eccentricity from GWTC-4 bounds the eccentric branching ratio below 5% at 90% confidence, with results consistent with quasi-circular models but highly model-dependent.
BHaHAHA provides the first infrastructure-agnostic open-source apparent horizon finder using a hyperbolic flow method, with reported 64x speedups on difficult cases and 2.1x faster dynamic tracking than AHFinderDirect.
The gwNRHME framework constructs a multi-modal non-spinning eccentric gravitational waveform surrogate by modulating quasi-circular models with universal eccentric functions, achieving median mismatches of ~9e-5 against 156 NR waveforms.
Presents a practical fully time-domain end-to-end likelihood for gravitational-wave inference with structured linear algebra and GPU acceleration.
A new harmonic-decomposition template search for precessing binary black holes in LIGO O3 data improves sensitivity by up to 28% and reduces computational cost by up to 5x with no new detections.
Derives closed 5D partial-wave Raman scattering amplitude via NS functions and computes non-vanishing dynamical ℓ=0 and static ℓ=1 scalar tidal Love numbers with RG running up to O(G²) for STBH.
Numerical simulations of eccentric Proca-star mergers show that relative phase between the stars controls post-merger fate and can generate odd-mode gravitational waves absent from black-hole mergers.
A universal anomalous dimension for multipole moments in GR is derived via two EFT methods and applied to resum short-distance logarithmic tails in binary gravitational waveforms.
Stable neutron-star configurations denser than black holes exist in quasi-topological gravity and may produce detectable gravitational-wave echoes.
Spinning test particles around rotating hairy black holes show finite-time instability in localized regions of the (spin, hair-parameter) plane that reorganize the strong-field phase space compared to Kerr.
A vertical long-wire suspended gradiometer configuration amplifies gravitational wave signals from order h to order h L/D by separating gravitational force from moment of inertia.
Dynamical formation in globular clusters produces a robust second black-hole mass peak at ~70 solar masses from second-generation mergers when the first-generation spectrum is truncated by pair-instability supernovae.
Maximum-likelihood-based posterior predictive checks detect model misspecification better than event-level versions for uncertain spin tilts, but current detector sensitivity limits their power; the Gaussian Component Spins model underpredicts high spin magnitudes and overpredicts anti-aligned tilts
Simulations show a 40-50 solar-mass black-hole cutoff is not guaranteed to be confidently recovered from GWTC-4-like catalogs, spurious detections are unlikely, and O4 data would reduce cutoff-mass uncertainty by at least 20 percent while yielding only a lower bound on the carbon-alpha reaction rate
GWTC-4.0 data shows low-spin black holes up to 70 solar masses, moving the low-spin cutoff to 68.5 solar masses and favoring a high pair-instability mass gap.
Semi-analytic waveform model for scalar environments around black hole binaries is validated against numerical relativity and applied to LIGO-Virgo-KAGRA data to obtain upper limits on scalar densities with tentative evidence in GW190728.
GW250114 data confirm the remnant is consistent with a Kerr black hole and bound the dominant quadrupolar mode frequency to within a few percent of the GR prediction, with constraints tighter than prior multi-event catalogs.
BHPTNRSur2dq1e3 is a new surrogate model for spinning intermediate-mass-ratio black hole binary gravitational waves, constructed from ppBHPT training data with domain decomposition for retrograde modes and calibrated to NR simulations.
Bayesian inference on LVK O1-O3 events with eccentric aligned-spin waveforms yields log10 Bayes factors of 1.77-4.75 favoring eccentricity for GW200129, GW190701 and GW200208_22, and >99.5% probability that at least one of 57 events is eccentric under an astrophysically motivated rate prior.
No evidence for core-collapse formed low-spin IMBHs in GWTC-4, with 90% upper limit on merger rate of 0.077 Gpc^{-3} yr^{-1}, low-spin BH mass truncation at 65 solar masses consistent with pair-instability gap lower edge, and high-spin IMBHs from hierarchical mergers.
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.
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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Constraints on the Primordial Black Hole Abundance using Pulsar Parameter Drifts
The first search for scalar-induced gravitational waves via pulsar parameter drifts yields f_PBH < 10^{-10} (95% CL) for PBH masses 0.3 to 4e4 solar masses, strongly disfavoring a primordial black hole origin for LVK binary black holes.
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Testing the Kerr hypothesis beyond the quadrupole with GW241011
GW241011 data shows consistency with Kerr black holes for both quadrupole and octupole moments and delivers the first observational bounds on spin-induced octupole deviations.
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Population Properties of Binary Black Holes with Eccentricity
First joint population inference on binary black hole eccentricity from GWTC-4 bounds the eccentric branching ratio below 5% at 90% confidence, with results consistent with quasi-circular models but highly model-dependent.
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BHaHAHA: A Fast, Robust Apparent Horizon Finder Library for Numerical Relativity
BHaHAHA provides the first infrastructure-agnostic open-source apparent horizon finder using a hyperbolic flow method, with reported 64x speedups on difficult cases and 2.1x faster dynamic tracking than AHFinderDirect.
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Including higher-order modes in a quadrupolar eccentric numerical relativity surrogate using universal eccentric modulation functions
The gwNRHME framework constructs a multi-modal non-spinning eccentric gravitational waveform surrogate by modulating quasi-circular models with universal eccentric functions, achieving median mismatches of ~9e-5 against 156 NR waveforms.
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Accelerated Time-domain Analysis for Gravitational Wave Astronomy
Presents a practical fully time-domain end-to-end likelihood for gravitational-wave inference with structured linear algebra and GPU acceleration.
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Search for Precessing Binary Black Holes in Advanced LIGO's Third Observing Run using Harmonic Decomposition
A new harmonic-decomposition template search for precessing binary black holes in LIGO O3 data improves sensitivity by up to 28% and reduces computational cost by up to 5x with no new detections.
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5-Dimensional Gravitational Raman Scattering: Scalar Wave Perturbations in Schwarzschild-Tangherlini Spacetime
Derives closed 5D partial-wave Raman scattering amplitude via NS functions and computes non-vanishing dynamical ℓ=0 and static ℓ=1 scalar tidal Love numbers with RG running up to O(G²) for STBH.
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Eccentric mergers of binary Proca stars
Numerical simulations of eccentric Proca-star mergers show that relative phase between the stars controls post-merger fate and can generate odd-mode gravitational waves absent from black-hole mergers.
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Resummation of Universal Tails in Gravitational Waveforms
A universal anomalous dimension for multipole moments in GR is derived via two EFT methods and applied to resum short-distance logarithmic tails in binary gravitational waveforms.
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Neutron stars more compact than black holes as a probe of strong-field gravity
Stable neutron-star configurations denser than black holes exist in quasi-topological gravity and may produce detectable gravitational-wave echoes.
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Spin-Hair Induced Chaos of Spinning Test Particles in Rotating Hairy Black Holes
Spinning test particles around rotating hairy black holes show finite-time instability in localized regions of the (spin, hair-parameter) plane that reorganize the strong-field phase space compared to Kerr.
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Mechanical Long Baseline Differential Gradiometers as Low Frequency Gravitational Wave Detectors
A vertical long-wire suspended gradiometer configuration amplifies gravitational wave signals from order h to order h L/D by separating gravitational force from moment of inertia.
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Second-Generation Mass Peak in the Gravitational-Wave Population as a Probe of Globular Clusters
Dynamical formation in globular clusters produces a robust second black-hole mass peak at ~70 solar masses from second-generation mergers when the first-generation spectrum is truncated by pair-instability supernovae.
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Posterior Predictive Checks for Gravitational-wave Populations: Limitations and Improvements
Maximum-likelihood-based posterior predictive checks detect model misspecification better than event-level versions for uncertain spin tilts, but current detector sensitivity limits their power; the Gaussian Component Spins model underpredicts high spin magnitudes and overpredicts anti-aligned tilts
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Measurement prospects for the pair-instability mass cutoff with gravitational waves
Simulations show a 40-50 solar-mass black-hole cutoff is not guaranteed to be confidently recovered from GWTC-4-like catalogs, spurious detections are unlikely, and O4 data would reduce cutoff-mass uncertainty by at least 20 percent while yielding only a lower bound on the carbon-alpha reaction rate
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A new group of low-spin $50-70M_\odot$ Black Holes and the high pair-instability mass cutoff
GWTC-4.0 data shows low-spin black holes up to 70 solar masses, moving the low-spin cutoff to 68.5 solar masses and favoring a high pair-instability mass gap.
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Scalar fields around black hole binaries in LIGO-Virgo-KAGRA
Semi-analytic waveform model for scalar environments around black hole binaries is validated against numerical relativity and applied to LIGO-Virgo-KAGRA data to obtain upper limits on scalar densities with tentative evidence in GW190728.
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Black Hole Spectroscopy and Tests of General Relativity with GW250114
GW250114 data confirm the remnant is consistent with a Kerr black hole and bound the dominant quadrupolar mode frequency to within a few percent of the GR prediction, with constraints tighter than prior multi-event catalogs.
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Gravitational wave surrogate model for spinning, intermediate mass ratio binaries based on perturbation theory and numerical relativity
BHPTNRSur2dq1e3 is a new surrogate model for spinning intermediate-mass-ratio black hole binary gravitational waves, constructed from ppBHPT training data with domain decomposition for retrograde modes and calibrated to NR simulations.
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Evidence for eccentricity in the population of binary black holes observed by LIGO-Virgo-KAGRA
Bayesian inference on LVK O1-O3 events with eccentric aligned-spin waveforms yields log10 Bayes factors of 1.77-4.75 favoring eccentricity for GW200129, GW190701 and GW200208_22, and >99.5% probability that at least one of 57 events is eccentric under an astrophysically motivated rate prior.
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How do the LIGO-Virgo-KAGRA's Heavy Black Holes Form? No evidence for core-collapse Intermediate-mass black holes in GWTC-4
No evidence for core-collapse formed low-spin IMBHs in GWTC-4, with 90% upper limit on merger rate of 0.077 Gpc^{-3} yr^{-1}, low-spin BH mass truncation at 65 solar masses consistent with pair-instability gap lower edge, and high-spin IMBHs from hierarchical mergers.
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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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Probing Kerr Symmetry Breaking with LISA Extreme-Mass-Ratio Inspirals
LISA EMRIs can constrain deviations from Kerr equatorial symmetry to 10^{-2} and axial symmetry to 10^{-3} using Analytic Kludge waveforms and Fisher analysis.
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Inference of recoil kicks from binary black hole mergers up to GWTC--4 and their astrophysical implications
Recoil kicks are inferred for GWTC-4 binary black hole events with values up to nearly 1000 km/s for some, yielding retention probabilities of 1-5% in globular clusters and 70-100% in elliptical galaxies.
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Confronting eikonal and post-Kerr methods with numerical evolution of scalar field perturbations in spacetimes beyond Kerr
Numerical simulations benchmark the eikonal and post-Kerr approximations for quasinormal modes in deformed Kerr spacetimes, quantifying their errors relative to expected observational precision.
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Biased parameter inference of eccentric, spin-precessing binary black holes
Eccentric BBH signals recovered with quasi-circular precessing models show biases in chirp mass and χ_p; Bayes factors favor eccentric aligned-spin models when both eccentricity and precession are present.
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Neural Post-Einsteinian Test of General Relativity with the Third Gravitational-Wave Transient Catalog
Neural post-Einsteinian analysis of GWTC-3 finds no GR violation and sets constraints covering both post-Newtonian and beyond-post-Newtonian deviations in a single theory-agnostic setup.
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Binary black holes in the heat of merger
Develops a frequency-domain approximant for tidal heating in nonspinning black hole binaries that extends to merger and includes horizon parameters.
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Assessment of normalizing flows for parameter estimation on time-frequency representations of gravitational-wave data
GP15 maps BBH spectrograms to parameter posteriors via residual networks and normalizing flows, producing results consistent with LVK analyses on GWTC-2.1 and GWTC-3 events while running in seconds.
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Gravitational Wave Hyperbolic Catalog: Reanalyzing High-Mass Gravitational Wave Signals Using Hyperbolic Waveforms
Reanalysis finds GW190521 prefers hyperbolic waveforms over quasi-circular precessing ones with ln Bayes factor 3.71, while other high-mass events and GW231123 favor the latter; mock signals indicate distinguishability challenges for high-mass precessing cases.
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Rapid data quality investigations of gravitational-wave events with the Data Quality Report Builder toolkit
DQRbuild toolkit automates data quality vetting for gravitational-wave events, recovering 96% of human-identified issues from O3 with a 24% false alarm rate.
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Gravitational-wave astronomy requires population-informed parameter estimation
Population-informed hierarchical parameter estimation is required for unbiased astrophysical interpretation of gravitational-wave events rather than using standard individual posteriors with reference priors.
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GW190711_030756 and GW200114_020818: astrophysical interpretation of two asymmetric binary black hole mergers in the IAS catalog
Two asymmetric BBH mergers are characterized with mass ratios 0.35 and ≤0.20; one shows high spins, negative χ_eff, and strong precession, suggesting an emerging population of massive rapidly spinning systems.
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An Implementation to Identify the Properties of Multiple Population of Gravitational Wave Sources
GWKokab is a new modular JAX framework that uses normalizing flow samplers for efficient inference on subpopulations of compact binary mergers.
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GstLAL O4 Online Results Paper
GstLAL produced low-latency alerts for 250 astrophysically plausible gravitational-wave candidates during O4, providing the first upload for 222 and the sole upload for 75, with 88 percent of significant catalog events detected and 93 percent classification agreement.
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Residual Test for the Third Gravitational-Wave Transient Catalog
Residuals after subtracting best-fit waveforms from GWTC-3 events show no significant deviation from noise according to three standard goodness-of-fit tests.
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Tests of General Relativity with GWTC-3
No evidence for physics beyond general relativity is found in the analysis of 15 GW events from GWTC-3, with consistency in residuals, PN parameters, and remnant properties.
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Waveform Modelling for the Laser Interferometer Space Antenna
A review of existing waveform models for LISA sources and the challenges that must still be overcome.