A new gravitational wave event reveals a binary black hole merger with total mass 190-265 solar masses, indicating black holes can form via gravitational-wave driven mergers beyond standard stellar channels.
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Bilby: A user-friendly Bayesian inference library for gravitational-wave astronomy
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abstract
Bayesian parameter estimation is fast becoming the language of gravitational-wave astronomy. It is the method by which gravitational-wave data is used to infer the sources' astrophysical properties. We introduce a user-friendly Bayesian inference library for gravitational-wave astronomy, Bilby. This python code provides expert-level parameter estimation infrastructure with straightforward syntax and tools that facilitate use by beginners. It allows users to perform accurate and reliable gravitational-wave parameter estimation on both real, freely-available data from LIGO/Virgo, and simulated data. We provide a suite of examples for the analysis of compact binary mergers and other types of signal model including supernovae and the remnants of binary neutron star mergers. These examples illustrate how to change the signal model, how to implement new likelihood functions, and how to add new detectors. Bilby has additional functionality to do population studies using hierarchical Bayesian modelling. We provide an example in which we infer the shape of the black hole mass distribution from an ensemble of observations of binary black hole mergers.
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representative citing papers
The first informative astrophysical calibration of gravitational-wave detectors is reported using GW240925 and GW250207.
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.
The central compact object 1E 1207.4-5209 emits pulsed radio waves at its 0.4-second spin period, revealing it as a faint radio pulsar.
Introduces a generalized fast framework for modeling interaction-powered transients with arbitrary CSM profiles and multi-wavelength outputs.
Simulations forecast that 10 years of Einstein Telescope and Cosmic Explorer data could detect the cosmic dipole magnitude using strongly lensed GW events, with tighter bounds from combining double, triple, and quadruple lensed systems.
A reference-frequency-independent detection statistic for eccentric binary mergers is introduced and applied to GW200105, yielding ln B ≤ 0.9 in favor of the eccentric aligned-spin model over the quasi-circular precessing model.
Dingo-Pop uses a transformer to perform amortized, end-to-end population inference from GW strain data in seconds, bypassing per-event Monte Carlo sampling.
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.
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.
LIGO and Virgo detected 39 compact binary coalescence events in O3a, including 13 new ones, with black hole binaries up to 150 solar masses and the first significantly asymmetric mass ratios.
SEOBNRv6EHM reduces parameter biases for eccentric binaries versus prior models and shows mild support for eccentricity in five catalog events plus comparable unbound fits for three high-mass events.
FIREFLY algorithm enables 200-fold faster multi-mode ringdown analysis for space-borne gravitational wave detectors while remaining compatible with time-delay interferometry.
Neural network surrogate approximates precessing compact binary gravitational waveforms up to 1000x faster than the base EOB model with validated accuracy.
pyEFPEHM extends prior PN models to include higher-order quasi-circular phasing, generalized precession solutions, and eccentric corrections up to 1PN in selected multipoles for eccentric precessing binaries with matter effects.
Unmodeled point-mass lensing produces a spurious nonzero graviton mass posterior in GW231123 that vanishes when lensing is included in the analysis.
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
GW250114 data constrains GR deviations in merger amplitude to 10% and frequency to 4% at 90% CL, with first bounds on the (4,4) mode frequency at 6%.
GWTC-4 data show a transition to nearly all hierarchical mergers above 46 solar masses, with the hierarchical rate peaking at 15.7 solar masses, indicating mass-dependent substructure in black hole spins.
A two-step Bayesian reweighting scheme using Euclid galaxy locations boosts the Bayes factor for true lensed GW pairs by a factor of about 10 while lowering it for unlensed coincidences.
Hierarchical Bayesian inference on 20 high-SNR simulated binary neutron star events shows a linear lnΛ-lnQ relation suffices and constrains dynamical Chern-Simons gravity length scale to ≤10 km.
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.
F-statistic framework analytically maximizes over distance and polarization to enable faster Bayesian inference of compact binary coalescences with a new evidence formulation that matches full frequency-domain results at lower cost.
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.
citing papers explorer
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GW231123: a Binary Black Hole Merger with Total Mass 190-265 $M_{\odot}$
A new gravitational wave event reveals a binary black hole merger with total mass 190-265 solar masses, indicating black holes can form via gravitational-wave driven mergers beyond standard stellar channels.
-
GW240925 and GW250207: Astrophysical Calibration of Gravitational-wave Detectors
The first informative astrophysical calibration of gravitational-wave detectors is reported using GW240925 and GW250207.
-
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.
-
Pulsed radio emission from a Central Compact Object
The central compact object 1E 1207.4-5209 emits pulsed radio waves at its 0.4-second spin period, revealing it as a faint radio pulsar.
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From mass-loss histories to lightcurves: a generalised framework for interaction-powered transients
Introduces a generalized fast framework for modeling interaction-powered transients with arbitrary CSM profiles and multi-wavelength outputs.
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Prospect of Measuring the Cosmic Dipole by Strongly Lensed Gravitational Waves Associated with Galaxy Surveys
Simulations forecast that 10 years of Einstein Telescope and Cosmic Explorer data could detect the cosmic dipole magnitude using strongly lensed GW events, with tighter bounds from combining double, triple, and quadruple lensed systems.
-
A universal framework to identify eccentric binary mergers: GW200105 case study
A reference-frequency-independent detection statistic for eccentric binary mergers is introduced and applied to GW200105, yielding ln B ≤ 0.9 in favor of the eccentric aligned-spin model over the quasi-circular precessing model.
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End-to-End Population Inference from Gravitational-Wave Strain using Transformers
Dingo-Pop uses a transformer to perform amortized, end-to-end population inference from GW strain data in seconds, bypassing per-event Monte Carlo sampling.
-
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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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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GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
LIGO and Virgo detected 39 compact binary coalescence events in O3a, including 13 new ones, with black hole binaries up to 150 solar masses and the first significantly asymmetric mass ratios.
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Eccentric and unbound compact binaries in the LIGO-Virgo-KAGRA catalog: parameter estimation and waveform systematics with SEOBNRv6EHM
SEOBNRv6EHM reduces parameter biases for eccentric binaries versus prior models and shows mild support for eccentricity in five catalog events plus comparable unbound fits for three high-mass events.
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Cracking Gravitational Wave Multiple Ringdown Modes in Space
FIREFLY algorithm enables 200-fold faster multi-mode ringdown analysis for space-borne gravitational wave detectors while remaining compatible with time-delay interferometry.
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Fast neural network surrogate for multimodal effective-one-body gravitational waveforms from generically precessing compact binaries
Neural network surrogate approximates precessing compact binary gravitational waveforms up to 1000x faster than the base EOB model with validated accuracy.
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Post-Newtonian inspiral waveform model for eccentric precessing binaries with higher-order modes and matter effects
pyEFPEHM extends prior PN models to include higher-order quasi-circular phasing, generalized precession solutions, and eccentric corrections up to 1PN in selected multipoles for eccentric precessing binaries with matter effects.
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GW231123: False Massive Graviton Signatures from Unmodeled Point-Mass Lensing
Unmodeled point-mass lensing produces a spurious nonzero graviton mass posterior in GW231123 that vanishes when lensing is included in the analysis.
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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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Plunge-Merger-Ringdown Tests of General Relativity with GW250114
GW250114 data constrains GR deviations in merger amplitude to 10% and frequency to 4% at 90% CL, with first bounds on the (4,4) mode frequency at 6%.
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Signatures of a subpopulation of hierarchical mergers in the GWTC-4 gravitational-wave dataset
GWTC-4 data show a transition to nearly all hierarchical mergers above 46 solar masses, with the hierarchical rate peaking at 15.7 solar masses, indicating mass-dependent substructure in black hole spins.
-
Improved Identification of Strongly Lensed Gravitational Waves with Host Galaxy Locations
A two-step Bayesian reweighting scheme using Euclid galaxy locations boosts the Bayes factor for true lensed GW pairs by a factor of about 10 while lowering it for unlensed coincidences.
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Inferring neutron-star Love-Q relations from gravitational waves in the hierarchical Bayesian framework
Hierarchical Bayesian inference on 20 high-SNR simulated binary neutron star events shows a linear lnΛ-lnQ relation suffices and constrains dynamical Chern-Simons gravity length scale to ≤10 km.
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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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A Robust and Efficient F-statistic-based Framework for Consistent Bayesian Inference of Compact Binary Coalescences
F-statistic framework analytically maximizes over distance and polarization to enable faster Bayesian inference of compact binary coalescences with a new evidence formulation that matches full frequency-domain results at lower cost.
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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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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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Computationally efficient models for the dominant and sub-dominant harmonic modes of precessing binary black holes
IMRPhenomXPHM is a new computationally efficient phenomenological model for precessing binary black hole gravitational-wave signals that incorporates higher-order modes via twisting-up maps from non-precessing waveforms.
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dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
dynesty is an open-source Python package for dynamic nested sampling that improves efficiency in Bayesian posterior and evidence estimation compared to MCMC on certain problems.
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Tests of General Relativity with the Binary Black Hole Signals from the LIGO-Virgo Catalog GWTC-1
Binary black hole signals in GWTC-1 are consistent with general relativity predictions, with an improved graviton mass bound of mg ≤ 4.7 × 10^{-23} eV/c² at 90% credible level.
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A parametric signal plus noise inference framework for short duration non-Gaussian noise transients
Bilby-antiglitch jointly models astrophysical signals and quasi-physical glitches to recover true source properties from simulated gravitational wave data contaminated by loud non-Gaussian transients.
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EP251023a: A fast X-ray transient featuring a magnetar-powered optical internal plateau followed by a steep decay
EP251023a is a new extragalactic fast X-ray transient whose optical light curve is interpreted as a rare magnetar-powered internal plateau with derived upper limits on spin period and magnetic field.
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The Chirp-Mass Ladder: A New Rung Emerges
The chirp-mass distribution of GW-detected binary black holes shows a ladder of peaks doubling in mass, with a new intermediate peak at 19 solar masses confirming a prior prediction from the hierarchical merger model.
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Probing a new subclass of llGRB-SN transients: Insights from EP250304a and its associated supernova
EP250304a/SN 2025fhm is presented as a member of an emerging subclass of shocked cocoon-dominated low-luminosity GRB-SNe based on spectral, photometric, and light-curve modeling comparisons to prior events.
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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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Is the Binary Black Hole Population Inference from Gravitational-Wave Data Robust?
Waveform modeling uncertainties can distort features in the binary black hole mass distribution inferred from gravitational-wave data more than statistical uncertainties.
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Constraints on primordial black holes from the first part of LIGO-Virgo-KAGRA fourth observing run
LIGO-Virgo-KAGRA O4a data yields the strongest constraints on primordial black hole abundance for 0.6-100 solar masses, with resolvable mergers dominating the limits and no compelling evidence for a PBH contribution in joint fits with astrophysical black holes.
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The Impact of Spin Priors on Parameterized Tests of General Relativity
Spin prior choices propagate into tests of GR via the 1.5PN deviation parameter δφ̂3 in a non-trivial, event-dependent way, with stronger effects for short-inspiral events and partial degeneracy with χ_eff when the deviation is included.
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Bayesian Analysis of Gravitational Wave Microlensing Effects from Galactic Double White Dwarfs
Bayesian analysis of simulated Taiji observations shows microlensing from lenses above 10^5 solar masses can be distinguished from unlensed DWD signals when separation is below 3 Einstein radii, while lower masses or larger separations cannot.
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Detectability of Gravitational-Wave Memory with LISA: A Bayesian Approach
Bayesian parameter estimation on simulated LISA data establishes conditions for detecting displacement memory in MBHB events and projects observation rates from population models.
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GW231123: Overlapping Gravitational Wave Signals?
GW231123 data favors an overlapping two-signal model over a single merger with Bayes factors of 100-10000, mitigating waveform-dependent discrepancies and suggesting possible gravitational lensing.
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Gravitational-wave parameter estimation to the Moon and back: massive binaries and the case of GW231123
LGWA could observe more than one third of known binary black hole events, detect ~90 mergers per year, and measure chirp mass better than third-generation detectors for massive systems.
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Impact of facility timing and coordination for next-generation gravitational-wave detectors
Simulations of ET and CE networks show delays degrade localization metrics far more than SNR, with LIGO India greatly reducing the impact for multi-messenger and stochastic searches.
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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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GW250114: testing Hawking's area law and the Kerr nature of black holes
GW250114 data confirm the remnant black hole ringdown frequencies lie within 30% of Kerr predictions and that the final horizon area is larger than the sum of the progenitors' areas to high credibility.
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Disentangling spinning and nonspinning binary black hole populations with spin sorting
Spin sorting with the default spin model distinguishes spinning and nonspinning binary black hole populations in simulations and shows real data rule out a fully nonspinning population but allow mixed ones with up to 80% nonspinning sources.
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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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A practical Bayesian method for gravitational-wave ringdown analysis with multiple modes
FIREFLY accelerates multi-mode GW ringdown analysis by analytically marginalizing QNM amplitudes and phases via Bayesian principles and importance sampling.
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Tests of General Relativity with GW230529: a neutron star merging with a lower mass-gap compact object
Parameterized inspiral tests on GW230529 find consistency with GR, with |δφ̂_{-2}| ≲ 8×10^{-5} and ℓ_GB ≲ 0.51 M_⊙ in ESGB theories.
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Tests of General Relativity with Binary Black Holes from the second LIGO-Virgo Gravitational-Wave Transient Catalog
No evidence for deviations from general relativity is found in LIGO-Virgo binary black hole events, with improved constraints on waveform parameters, graviton mass, and ringdown properties.
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Fast targeted gravitational-wave followup search for compact binary mergers using GSTLAL pipeline
A targeted gravitational-wave search modifies the GstLAL likelihood ratio with a sky localization prior from EM triggers, showing improved detection efficiency in injection studies while controlling false alarms.