In a curvature-coupled propagation framework for modified gravity, gravitational-wave lensing in wave optics shows persistent infrared interactions that prevent the amplification factor from approaching unity at zero frequency, requiring an interacting Green function and partial-wave treatment.
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The Confrontation between General Relativity and Experiment
Canonical reference. 94% of citing Pith papers cite this work as background.
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The status of experimental tests of general relativity and of theoretical frameworks for analyzing them are reviewed and updated. Einstein's equivalence principle (EEP) is well supported by experiments such as the Eotvos experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational-wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.
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Exact quasi-bound scalar field states in dyonic Kerr-Sen black holes are expressed as confluent Heun functions with quantized frequencies showing exponential growth for positive real parts inside the horizons, supporting chronology protection.
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.
Field equation analysis near infinity in massive Hellings-Nordtvedt theory restricts the model to two single-coupling sectors; the A²R sector yields asymptotically flat Schwarzschild black holes with radial vector fields and neutron stars with measurable deviations from GR while satisfying weak-fiel
In Ricci-coupled scalar-Gauss-Bonnet gravity, the change in scalar charge during binary black hole mergers generates a scalar memory contribution that modifies the total memory signal on observable timescales.
A master screening equation is derived for luminal Horndeski gravity that recovers Vainshtein and Chameleon mechanisms and introduces Phaedrus screening with screening radius scaling linearly with source mass.
A full-covariance formalism for PTA-astrometry ORF estimators forecasts graviton-mass upper limits of 4.41e-24 eV/c2 for current-like setups and 0.48e-24 eV/c2 for SKA/Theia-like future setups, with astrometry adding significant power in the latter case.
A reduction scheme transforms arbitrary N-term scalar and matrix recurrence relations from black hole perturbations in modified gravity into three-term relations solvable by continued fractions.
Multi-scalar-tensor gravity admits an exact covariant thermodynamic interpretation as an imperfect fluid whose heat flux involves a coupling-derived factor χ and a residual gradient sector, yielding multi-field thermal diagnostics and a GR-attractor criterion that is stricter than simple freezing of
Treating the baryogenesis operator as part of the action yields modified Friedmann and Raychaudhuri equations with an effective Planck mass M_eff² = M_Pl² - 2λ ∇_μ J^μ for the vector-density realization of the current.
RG-improved black hole spacetimes with scale-dependent gravitational coupling are derived as vacuum solutions to 2D Horndeski master field equations, embedding prior works and exposing implementation discrepancies.
Self-force theory is extended to compute merger and ringdown waveforms in beyond-GR black hole binaries under the extreme mass-ratio approximation, with first calculations of self-force corrections to the merger waveform.
Stable neutron-star configurations denser than black holes exist in quasi-topological gravity and may produce detectable gravitational-wave echoes.
Hydrodynamical simulations in f(R) gravity using Illustris-TNG find observable 20% effects on high-z HI and stellar power spectra exceeding SKA errors, plus changes in disc galaxy formation.
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.
Quantum matter sources an operator-valued Shapiro delay that promotes causal boundaries to noncommuting observables and allows superpositions of causal relations between spacetime points.
Numerical simulations of collapsing scalarized neutron stars show scalar radiation energy of order 10^{-3} solar masses, orders of magnitude above the tensor quadrupolar emission, potentially observable to test modified gravity.
UV completeness in scalar-tensor gravity restricts Yukawa fifth-force parameters α and λ to a finite wedge whose complement is ruled out, with part of the excluded domain below current experimental bounds.
Kinetic screening non-monotonically suppresses or enhances scalar quadrupolar emission from equal-mass neutron star binaries depending on screening radius versus wavelength, with a dipole re-emerging linearly with mass asymmetry.
Unified post-Newtonian analysis reveals that Palatini scalar-tensor theories often face weaker Solar System bounds than metric versions due to stronger Yukawa suppression, with Palatini f(R) reproducing GR limits for point sources unlike metric f(R).
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}.
KiDS-Legacy weak lensing plus CMB data yields a 3 sigma deviation in light deflection from GR in a Lambda CDM background, with the signal driven by large-scale CMB lensing amplitudes.
Quadratic gravity with Weyl-squared and Ricci-squared terms produces PPN parameters that equal their GR values except for exponentially decaying corrections, with gamma identically 1 when the two mode masses are equal, yielding solar-system lower bounds m_R, m_W greater than or equal to 23 per AU.
Born-Infeld electrogravity yields a fundamental extremal dyonic black hole in the small-charge limit whose mass and horizon area depend only on the Born-Infeld constant, Newton’s constant, and the speed of light.
citing papers explorer
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Wave-optics gravitational wave lensing in modified gravity
In a curvature-coupled propagation framework for modified gravity, gravitational-wave lensing in wave optics shows persistent infrared interactions that prevent the amplification factor from approaching unity at zero frequency, requiring an interacting Green function and partial-wave treatment.
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Quasi-bound States of Scalar field inside the Dyonic Kerr-Sen Black Hole
Exact quasi-bound scalar field states in dyonic Kerr-Sen black holes are expressed as confluent Heun functions with quantized frequencies showing exponential growth for positive real parts inside the horizons, supporting chronology protection.
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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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Black holes and neutron stars in massive Hellings-Nordtvedt theory
Field equation analysis near infinity in massive Hellings-Nordtvedt theory restricts the model to two single-coupling sectors; the A²R sector yields asymptotically flat Schwarzschild black holes with radial vector fields and neutron stars with measurable deviations from GR while satisfying weak-fiel
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Scalar memory from compact binary coalescences
In Ricci-coupled scalar-Gauss-Bonnet gravity, the change in scalar charge during binary black hole mergers generates a scalar memory contribution that modifies the total memory signal on observable timescales.
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A Master Equation for Screening in Luminal Horndeski Gravity
A master screening equation is derived for luminal Horndeski gravity that recovers Vainshtein and Chameleon mechanisms and introduces Phaedrus screening with screening radius scaling linearly with source mass.
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Forecasting graviton-mass constraints from the full covariance of PTA-astrometry ORF estimators
A full-covariance formalism for PTA-astrometry ORF estimators forecasts graviton-mass upper limits of 4.41e-24 eV/c2 for current-like setups and 0.48e-24 eV/c2 for SKA/Theia-like future setups, with astrometry adding significant power in the latter case.
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Beyond Three Terms: Continued Fractions for Rotating Black Holes in Modified Gravity
A reduction scheme transforms arbitrary N-term scalar and matrix recurrence relations from black hole perturbations in modified gravity into three-term relations solvable by continued fractions.
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First-order thermodynamics of multi-scalar-tensor gravity
Multi-scalar-tensor gravity admits an exact covariant thermodynamic interpretation as an imperfect fluid whose heat flux involves a coupling-derived factor χ and a residual gradient sector, yielding multi-field thermal diagnostics and a GR-attractor criterion that is stricter than simple freezing of
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Gravitational baryogenesis beyond the spectator approximation
Treating the baryogenesis operator as part of the action yields modified Friedmann and Raychaudhuri equations with an effective Planck mass M_eff² = M_Pl² - 2λ ∇_μ J^μ for the vector-density realization of the current.
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Effective geometrodynamics for renormalization-group improved black-hole spacetimes in spherical symmetry
RG-improved black hole spacetimes with scale-dependent gravitational coupling are derived as vacuum solutions to 2D Horndeski master field equations, embedding prior works and exposing implementation discrepancies.
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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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Quantum Matter Makes Lightcones Quantum
Quantum matter sources an operator-valued Shapiro delay that promotes causal boundaries to noncommuting observables and allows superpositions of causal relations between spacetime points.
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Rapidly Rotating Neutron Star Collapse in Massive Scalar-Tensor Theories
Numerical simulations of collapsing scalarized neutron stars show scalar radiation energy of order 10^{-3} solar masses, orders of magnitude above the tensor quadrupolar emission, potentially observable to test modified gravity.
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Fifth-Force Constraints from UV-Complete Scalar-Tensor Gravity
UV completeness in scalar-tensor gravity restricts Yukawa fifth-force parameters α and λ to a finite wedge whose complement is ruled out, with part of the excluded domain below current experimental bounds.
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Scalar emission from binary neutron stars in scalar-tensor theories with kinetic screening
Kinetic screening non-monotonically suppresses or enhances scalar quadrupolar emission from equal-mass neutron star binaries depending on screening radius versus wavelength, with a dipole re-emerging linearly with mass asymmetry.
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Post-Newtonian Constraints on Scalar-Tensor Gravity
Unified post-Newtonian analysis reveals that Palatini scalar-tensor theories often face weaker Solar System bounds than metric versions due to stronger Yukawa suppression, with Palatini f(R) reproducing GR limits for point sources unlike metric f(R).
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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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Evidence for deviation in gravitational light deflection from general relativity at cosmological scales with KiDS-Legacy and CMB lensing
KiDS-Legacy weak lensing plus CMB data yields a 3 sigma deviation in light deflection from GR in a Lambda CDM background, with the signal driven by large-scale CMB lensing amplitudes.
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Parameterized Post-Newtonian Analysis of Quadratic Gravity and Solar System Constraints
Quadratic gravity with Weyl-squared and Ricci-squared terms produces PPN parameters that equal their GR values except for exponentially decaying corrections, with gamma identically 1 when the two mode masses are equal, yielding solar-system lower bounds m_R, m_W greater than or equal to 23 per AU.
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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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Another Look at the Weak-Field Limit of Generalized Hybrid Metric-Palatini Gravity
Generalized hybrid metric-Palatini gravity propagates a massless spin-2 mode and two massive scalars in the weak field; stability requires algebraic conditions on f derivatives at flat space, and planetary data constrain the scalar masses in a hierarchical regime.
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Neutron stars more compact than black holes in quasi-topological gravity: Equilibrium configurations and radial stability
In quasi-topological gravity, neutron stars can surpass black-hole compactness with universal high-density behavior and theory corrections that stabilize radially unstable configurations from general relativity.
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Dynamic Aspects of Bumblebee Gravity: Post-Newtonian Approach
Bumblebee gravity is self-consistent in PPN up to 1.5PN order only for λ = −ξ/2, producing non-zero α1, α2, a logarithmic U_B potential, and a pulsar-timing bound |ℓ| ≲ 1.6×10^{-9}.
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Can wormholes have vanishing Love numbers?
For a specific R=0 wormhole, the magnetic Love number for ℓ=2 vanishes to linear order in the regularization parameter under static axial gravitational perturbations.
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A note on methods for computing the critical curve of Kerr-like black holes
Bardeen's definition of black hole critical curves deviates from de Vries and Grenzebach definitions in homogeneous plasma by contracting with increasing density, contrary to prior expectations.
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Generalizing the CPL Parametrization through Dark Sector Interaction
Generalized interacting dark energy models with constant or dynamical couplings yield analytical density expressions but are not preferred over LambdaCDM by Bayesian evidence from DESI, Pantheon+, and CMB data.
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The properties and predictions of quasi-periodic oscillations around a black hole in nonlocal gravity
Nonlocal gravity shrinks the ISCO radius, boosts QPO frequencies, and constrains α/M ≤ 0.452 with M ≲ 43.6 M_⊙ for observed high-frequency QPOs under resonance models.
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Observational constraints on nonlocal black holes via gravitational lensing
Nonlocal black holes remain consistent with general relativity at the 1.13-sigma level after joint lensing and quasinormal-mode constraints.
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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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GRMHD and GRRT Simulations of Black Hole Accretion: Flares, Precession, and Complex Spacetimes
Simulations of accreting black holes in standard and complex spacetimes indicate that magnetic geometry, quantum corrections, and binary dynamics influence flares, precession, photon rings, and multi-wavelength variability, with potential EHT constraints.
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Detectability of secondary images from flares near Sgr A* with mock GRAVITY data
Bayesian fitting to mock GRAVITY data shows robust detection of secondary images from Sgr A* flares requires both an order-of-magnitude larger sample and astrometric uncertainties reduced to 40% of current levels for |ΔBIC| > 7.9.
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Equivalence Principle violation in metric-affine gravity and finite-temperature effects
Metric-affine gravity formulates equivalence principle violations via non-metricity that parallel finite-temperature mass-ratio shifts, and a generalized Fermi-Walker derivative shows no orthonormal tetrad propagates along observer worldlines.
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Polarization Birefringence and Waveform Systematics in GW231123
Analysis of GW231123 with IMRPhenomXPHM, IMRPhenomXO4a and NRSur7dq4 yields no waveform-independent evidence for polarization birefringence, with 90% upper limits on the derived coefficient of 0.378, 0.097 and 0.273 respectively.
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Constraining Lorentz symmetry breaking in bumblebee gravity with extreme mass-ratio inspirals
LISA can constrain the Lorentz symmetry breaking parameter ell in bumblebee gravity to O(10^{-4}) uncertainty via EMRI waveform analysis in the AAK framework.
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Constraints on Einstein-aether gravity from the precision timing of PSR J1738+0333
Precision timing of PSR J1738+0333 from EPTA and NANOGrav data yields the tightest strong-field constraints on Einstein-aether parameters from any single binary pulsar.
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Tests of scalar polarizations with multi-messenger events
Bayesian analysis of GW170817 with PPE framework and EM polarization constraints shows mild preference for scalar mode in quadrupole harmonics and improves bounds on non-GR parameters by up to 60%.
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Gravitational Wave Signatures of Schwarzschild Black Hole in a Generalized Dehnen-Type $(1,4,\gamma)$ Dark Matter Halo
Numerical study of timelike geodesics and millihertz gravitational waves from periodic orbits around a Schwarzschild black hole embedded in a (1,4,γ) Dehnen dark matter halo.
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Probing Kalb-Ramond gravity with charged rotating black holes: constraints from EHT observations
EHT shadow observations constrain the Lorentz-violating parameter ℓ in Kalb-Ramond gravity for charged rotating black holes to roughly |ℓ| ≲ 0.1-0.2, with an upper bound ℓ ≲ 0.19 from Sgr A*.
- Spontaneous Symmetry Breaking and the Vacuum Displacement Principle: From Galactic Scales to Cosmic Fine-Tuning
- Energy conditions in static, spherically symmetric spacetimes and effective geometries
- Dynamical Black Hole Thermodynamics in Modified Gravity