Pub Date : 2026-10-16DOI: 10.1088/1361-6382/aeb5c4
Oleksii Yanchyshen,Eva Hackmann,Claus Lämmerzahl
Abstract We derive general relativistic Gaussian equations for osculating elements for orbits under the influence of a perturbing force without any restrictions in an underlying Schwarzschild space-time. Such a formulation provides a way to describe the evolution of orbital parameters in strong gravity relativistic settings. As examples of external forces we considered Kerr and q-metric space-times generated forces, for which we solve equations for osculating elements in linear approximation. For the Kerr space-time in the post-Newtonian limit, our result reproduces the well-known Lense-Thirring precession of the longitude of the ascending node.
{"title":"General orbital perturbation theory in Schwarzschild space-time","authors":"Oleksii Yanchyshen,Eva Hackmann,Claus Lämmerzahl","doi":"10.1088/1361-6382/aeb5c4","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb5c4","url":null,"abstract":"Abstract We derive general relativistic Gaussian equations for osculating elements for orbits under the influence of a perturbing force without any restrictions in an underlying Schwarzschild space-time. Such a formulation provides a way to describe the evolution of orbital parameters in strong gravity relativistic settings. As examples of external forces we considered Kerr and q-metric space-times generated forces, for which we solve equations for osculating elements in linear approximation. For the Kerr space-time in the post-Newtonian limit, our result reproduces the well-known Lense-Thirring precession of the longitude of the ascending node.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"32 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-16DOI: 10.1088/1361-6382/aeb595
Jossian A. García,Vicente Sierra,Claudia Moreno,Javier M. Antelis
Abstract Gravitational wave signals from core-collapse supernovae encode critical astrophysical information, including key astrophysical parameters such as the ratio of rotational kinetic to gravitational potential energy at bounce, pre-collapse differential rotation, and the nuclear equation of state. However, the limited number of observed core-collapse supernovae events makes it challenging to build robust data-driven models. The generation of synthetic gravitational wave signals from core-collapse supernovae can therefore provide a valuable tool for data augmentation in machine learning pipelines, particularly for the training and testing of detection and parameter estimation algorithms. Although recent efforts have explored the use of generative models to synthesize waveform-like data, existing approaches lack the ability to condition outputs on specific astrophysical parameters. To address this, we propose a model capable of generating gravitational wave signals conditioned on astrophysical parameters of core-collapse supernovae rotation. The proposed conditional derivative generative adversarial network is trained on the Richers et al. catalog, which contains 1,824 simulated time-series gravitational wave waveforms and their corresponding physical parameters. Quantitative evaluation using time-domain similarity and distributional metrics shows that the generated signals reproduce the key statistical and morphological features of the original dataset. This work introduces a conditional generative framework for rotating core-collapse supernovae gravitational wave signals, that enables fast, low-cost data augmentation and parameterized modeling, improving ML-based detection and parameter estimation.
{"title":"Conditional Derivative GANs for Parameter-Conditioned Synthesis of Gravitational Waves from Core-Collapse Supernovae","authors":"Jossian A. García,Vicente Sierra,Claudia Moreno,Javier M. Antelis","doi":"10.1088/1361-6382/aeb595","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb595","url":null,"abstract":"Abstract Gravitational wave signals from core-collapse supernovae encode critical astrophysical information, including key astrophysical parameters such as the ratio of rotational kinetic to gravitational potential energy at bounce, pre-collapse differential rotation, and the nuclear equation of state. However, the limited number of observed core-collapse supernovae events makes it challenging to build robust data-driven models. The generation of synthetic gravitational wave signals from core-collapse supernovae can therefore provide a valuable tool for data augmentation in machine learning pipelines, particularly for the training and testing of detection and parameter estimation algorithms. Although recent efforts have explored the use of generative models to synthesize waveform-like data, existing approaches lack the ability to condition outputs on specific astrophysical parameters. To address this, we propose a model capable of generating gravitational wave signals conditioned on astrophysical parameters of core-collapse supernovae rotation. The proposed conditional derivative generative adversarial network is trained on the Richers et al. catalog, which contains 1,824 simulated time-series gravitational wave waveforms and their corresponding physical parameters. Quantitative evaluation using time-domain similarity and distributional metrics shows that the generated signals reproduce the key statistical and morphological features of the original dataset. This work introduces a conditional generative framework for rotating core-collapse supernovae gravitational wave signals, that enables fast, low-cost data augmentation and parameterized modeling, improving ML-based detection and parameter estimation.
","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-16DOI: 10.1088/1361-6382/aeb596
Timothy Clifton,Asta Heinesen,Oliver Pitt
Abstract The parameterized post-Newtonian (PPN) approach is the state of the art formalism for performing theory independent tests of weak-field gravity, and for constraining possible deviations from Einstein's theory. Within this framework, global conservation laws are useful for the calculation of dynamics and for giving meaning to parameters. In this paper we extend the concept of semi-conservative and fullyconservative theories of gravity to include situations in which compact astrophysical bodies are modeled as masses that are sensitive to their local environment, as relevant for theories that violate the strong equivalence principle. We find that globally conserved quantities can still exist in the presence of such sensitivities, and find their explicit forms when they do. We identify new ways of writing the coefficients that enter into the PPN metric when a theory of gravity admits conserved quantities in the presence of a sensitive body, and demonstrate the applicability of our approach by comparing it to known results in scalar-tensor theories of gravity.
{"title":"Post-Newtonian Global Conservation Laws in the Presence of Sensitive Bodies","authors":"Timothy Clifton,Asta Heinesen,Oliver Pitt","doi":"10.1088/1361-6382/aeb596","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb596","url":null,"abstract":"Abstract The parameterized post-Newtonian (PPN) approach is the state of the art formalism for performing theory independent tests of weak-field gravity, and for constraining possible deviations from Einstein's theory. Within this framework, global conservation laws are useful for the calculation of dynamics and for giving meaning to parameters. In this paper we extend the concept of semi-conservative and fullyconservative theories of gravity to include situations in which compact astrophysical bodies are modeled as masses that are sensitive to their local environment, as relevant for theories that violate the strong equivalence principle. We find that globally conserved quantities can still exist in the presence of such sensitivities, and find their explicit forms when they do. We identify new ways of writing the coefficients that enter into the PPN metric when a theory of gravity admits conserved quantities in the presence of a sensitive body, and demonstrate the applicability of our approach by comparing it to known results in scalar-tensor theories of gravity.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"4564 2 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-16DOI: 10.1088/1361-6382/aeb594
Chris Scott
Abstract We develop a medium effective field theory for a transverse-traceless spin-2 collective response in the unreduced electromagnetic near-field sector. The starting point is the observation that the usual Ward-projected radiative description removes source-bound longitudinal and toroidal multipole structure from the asymptotic photon Hilbert space. Retaining this local near-field structure leaves a compact dyality phase which defines a local, constrained $U(1)_phi$ connection over the ordinary electromagnetic $U(1)_Theta$ bundle. The mixed curvature invariant $int F_Theta wedge F_phi$ then supports codimension-two defect structure and a natural symmetric transverse-traceless bilinear. We identify the corresponding excitation as the dyality plasmon: a massive $ell=2$ collective mode of the dyality-ordered near-field medium. This mode is not a fundamental graviton and does not define a dynamical metric. It carries only the two projected tensor polarisations of the medium response, avoiding the consistency problems of nonlinear massive gravity.
The long-wavelength gravitational interpretation is of emergent $f(R)$-type vacuum elasticity, with the scalar and tensor branches belonging to distinct collective channels. We derive the medium-frame EFT, its projected source, propagator and admissible foliation structure. A schematic ultraviolet completion by electroweak-scale Witten dyons motivates the charge weights of the mixed-curvature sector; the gauge model itself is not constructed. Dirac quantisation then gives a conditional phase-velocity estimate $c_h/c = 1/bigl(2sqrt{alpha(m_Z^2),alpha(q^2)}bigr)$, yielding $c_h simeq 64.5c$ at the $Z$ pole. The scalar and vector channels are derived rather than projected away: the vector channel is empty and the surviving scalar is the condensate amplitude mode. A conditional pole location for the tensor branch and a cosmological resonant near-field search in the 250 - 470 GHz band follow.
{"title":"Spin-2 Sector of the Dyality-Ordered Electromagnetic Vacuum: An Effective Field Theory","authors":"Chris Scott","doi":"10.1088/1361-6382/aeb594","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb594","url":null,"abstract":"Abstract We develop a medium effective field theory for a transverse-traceless spin-2 collective response in the unreduced electromagnetic near-field sector. The starting point is the observation that the usual Ward-projected radiative description removes source-bound longitudinal and toroidal multipole structure from the asymptotic photon Hilbert space. Retaining this local near-field structure leaves a compact dyality phase which defines a local, constrained $U(1)_phi$ connection over the ordinary electromagnetic $U(1)_Theta$ bundle. The mixed curvature invariant $int F_Theta wedge F_phi$ then supports codimension-two defect structure and a natural symmetric transverse-traceless bilinear. We identify the corresponding excitation as the dyality plasmon: a massive $ell=2$ collective mode of the dyality-ordered near-field medium. This mode is not a fundamental graviton and does not define a dynamical metric. It carries only the two projected tensor polarisations of the medium response, avoiding the consistency problems of nonlinear massive gravity.
The long-wavelength gravitational interpretation is of emergent $f(R)$-type vacuum elasticity, with the scalar and tensor branches belonging to distinct collective channels. We derive the medium-frame EFT, its projected source, propagator and admissible foliation structure. A schematic ultraviolet completion by electroweak-scale Witten dyons motivates the charge weights of the mixed-curvature sector; the gauge model itself is not constructed. Dirac quantisation then gives a conditional phase-velocity estimate $c_h/c = 1/bigl(2sqrt{alpha(m_Z^2),alpha(q^2)}bigr)$, yielding $c_h simeq 64.5c$ at the $Z$ pole. The scalar and vector channels are derived rather than projected away: the vector channel is empty and the surviving scalar is the condensate amplitude mode. A conditional pole location for the tensor branch and a cosmological resonant near-field search in the 250 - 470 GHz band follow.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"286 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-15DOI: 10.1088/1361-6382/aeb524
Chris Stevens,Juan Antonio Valiente Kroon
Abstract We provide a formulation of the initial boundary value problem for Friedrich's extended conformal Einstein field equations in which boundary data is prescribed on a timelike hypersurface located at a finite position in the spacetime. Our construction relies on a gauge based on the properties of conformal geodesics and requires the boundary is ruled by timelike conformal geodesics. The consequences of this assumption on the timelike boundary are analysed and we identify a subset of maximally dissipative boundary conditions which are consistent with this assumption. For this class of consistent boundary conditions, and assuming the required compatibility conditions at the intersection of the initial and boundary hypersurfaces, we establish the local wellposedness of the initial boundary value problem and prove the propagation of the constraints.
{"title":"Wellposedness of the initial boundary value problem for the conformal field equations","authors":"Chris Stevens,Juan Antonio Valiente Kroon","doi":"10.1088/1361-6382/aeb524","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb524","url":null,"abstract":"Abstract We provide a formulation of the initial boundary value problem for Friedrich's extended conformal Einstein field equations in which boundary data is prescribed on a timelike hypersurface located at a finite position in the spacetime. Our construction relies on a gauge based on the properties of conformal geodesics and requires the boundary is ruled by timelike conformal geodesics. The consequences of this assumption on the timelike boundary are analysed and we identify a subset of maximally dissipative boundary conditions which are consistent with this assumption. For this class of consistent boundary conditions, and assuming the required compatibility conditions at the intersection of the initial and boundary hypersurfaces, we establish the local wellposedness of the initial boundary value problem and prove the propagation of the constraints.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"63 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-15DOI: 10.1088/1361-6382/aeb527
Olaf Müller
Abstract Bartnik conjecture is one of the prime open conjectures in mathematical relativity. There are many approaches to this conjecture that use (Lorentzian) conformal geometry. In this article, we show that if we replace the strong energy condition in Bartnik's splitting conjecture with the null energy condition, then in any dimension greater or equal to $3$ the conclusion of the conjecture would be wrong, more precisely: On a manifold of dimension at least $ 3$, {em every} globally hyperbolic spatially compact conformal class contains future complete metrics satisfying the null energy condition. In the spatially noncompact case, the same is true in the future of any Cauchy surface. The main tool is the flatzoomer method.
{"title":"Bartnik's splitting conjecture with the null energy condition","authors":"Olaf Müller","doi":"10.1088/1361-6382/aeb527","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb527","url":null,"abstract":"Abstract Bartnik conjecture is one of the prime open conjectures in mathematical relativity. There are many approaches to this conjecture that use (Lorentzian) conformal geometry. In this article, we show that if we replace the strong energy condition in Bartnik's splitting conjecture with the null energy condition, then in any dimension greater or equal to $3$ the conclusion of the conjecture would be wrong, more precisely: On a manifold of dimension at least $ 3$, {em every} globally hyperbolic spatially compact conformal class contains future complete metrics satisfying the null energy condition. In the spatially noncompact case, the same is true in the future of any Cauchy surface. The main tool is the flatzoomer method.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"14 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-15DOI: 10.1088/1361-6382/aeb525
Jane Glanzer,Adrian Helmling-Cornell,Alicia Calafat,Samantha Callos,Elenna Capote,Genevieve Connolly,Anamaria Effler,Tabata Aira Ferreira,Evan Goetz,Alan Matthew Knee,Joan-René René Mérou,Dishari Malakar,Benjamin Robert Mannix,Debasmita Nandi,Kiet Anh Pham,Robert Schofield,Preeti Sharma,Zach Yarbrough,Nicolas Arnaud,Beverly K Berger,Kim Burtnyk
Abstract LIGO detector characterization efforts enabled the confident detection of gravitational waves from hundreds of compact binary coalescences during the fourth observing run. Reliable production of high quality detector data and rapid noise mitigation efforts allow the extraction of the most in-depth knowledge of gravitational wave sources and their progenitors. In this paper we describe LIGO detector characterization activities during the second and third parts of O4—O4b and O4c. We summarize changes in detector configuration and performance at the LIGO Hanford and LIGO Livingston Observatories between the end of the first part of O4a and the end of O4c, including upgrades made during the commissioning break preceding O4b and during repairs performed in O4c. We describe instrumental investigations carried out at both sites designed to understand and subsequently mitigate the effect on detector sensitivity of transient glitches, narrowband spectral lines, and vibration-driven noise, among other data quality concerns. We then review the tools and procedures used to validate gravitational wave candidates and the data quality products thus supplied to searches for gravitational waves from compact binary coalescences and unmodeled transients, continuous gravitational waves, and the stochastic gravitational wave background. The efforts of the detector characterization group are essential for maintaining and improving the sensitivity and reliability of the LIGO detectors especially as observing runs lengthen and more events are detected. We conclude with prospects for LIGO detector characterization activities in future observing runs.
{"title":"LIGO Detector Characterization in the Second and Third Parts of the Fourth Observing Run","authors":"Jane Glanzer,Adrian Helmling-Cornell,Alicia Calafat,Samantha Callos,Elenna Capote,Genevieve Connolly,Anamaria Effler,Tabata Aira Ferreira,Evan Goetz,Alan Matthew Knee,Joan-René René Mérou,Dishari Malakar,Benjamin Robert Mannix,Debasmita Nandi,Kiet Anh Pham,Robert Schofield,Preeti Sharma,Zach Yarbrough,Nicolas Arnaud,Beverly K Berger,Kim Burtnyk","doi":"10.1088/1361-6382/aeb525","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb525","url":null,"abstract":"Abstract LIGO detector characterization efforts enabled the confident detection of gravitational waves from hundreds of compact binary coalescences during the fourth observing run. Reliable production of high quality detector data and rapid noise mitigation efforts allow the extraction of the most in-depth knowledge of gravitational wave sources and their progenitors. In this paper we describe LIGO detector characterization activities during the second and third parts of O4—O4b and O4c. We summarize changes in detector configuration and performance at the LIGO Hanford and LIGO Livingston Observatories between the end of the first part of O4a and the end of O4c, including upgrades made during the commissioning break preceding O4b and during repairs performed in O4c. We describe instrumental investigations carried out at both sites designed to understand and subsequently mitigate the effect on detector sensitivity of transient glitches, narrowband spectral lines, and vibration-driven noise, among other data quality concerns. We then review the tools and procedures used to validate gravitational wave candidates and the data quality products thus supplied to searches for gravitational waves from compact binary coalescences and unmodeled transients, continuous gravitational waves, and the stochastic gravitational wave background. The efforts of the detector characterization group are essential for maintaining and improving the sensitivity and reliability of the LIGO detectors especially as observing runs lengthen and more events are detected. We conclude with prospects for LIGO detector characterization activities in future observing runs.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"85 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-15DOI: 10.1088/1361-6382/aeb526
Daiki Tanabe,Yuki Inoue,Mario Juvenal III S Onglao
Abstract Improving sub-Hz sensitivity of gravitational wave (GW) detectors is important to detect heavier binary black hole mergers and study phenomena in stronger gravity fields. Torsion-bar-based GW detectors have been projected to focus on low-frequency GW. Among noise sources of GW detector, actuation noise induced by vibration of force sources and fluctuation of environmental magnetic fields is one that increases in low frequency. In this study, we propose photon-pressure actuator as a solution to isolate an actuator from seismic and magnetic noise. It can also be used as a photon calibrator. We designed an optical layout of the photon-pressure actuator having four beams independently controlled and applied it to CHRONOS experiment. Based on a realistic power control system, we estimated its maximum torque amplitude around yaw rotation axis as 1.0×10 -8 N•m and actuation efficiency as 6.6×10 -13 rad/V, which are sufficiently large for controlling the CHRONOS torsion bar. The actuation noise was estimated as 5.3×10 -19 rad•Hz -1/2 at 1 Hz, lower than the target sensitivity of CHRONOS. Assuming its usage as a photon calibrator, the estimated systematic error was 1.14%.
{"title":"Noise reduction in suspension control with photon-pressure actuator for CHRONOS gravitational wave detector","authors":"Daiki Tanabe,Yuki Inoue,Mario Juvenal III S Onglao","doi":"10.1088/1361-6382/aeb526","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb526","url":null,"abstract":"Abstract Improving sub-Hz sensitivity of gravitational wave (GW) detectors is important to detect heavier binary black hole mergers and study phenomena in stronger gravity fields. Torsion-bar-based GW detectors have been projected to focus on low-frequency GW. Among noise sources of GW detector, actuation noise induced by vibration of force sources and fluctuation of environmental magnetic fields is one that increases in low frequency. In this study, we propose photon-pressure actuator as a solution to isolate an actuator from seismic and magnetic noise. It can also be used as a photon calibrator. We designed an optical layout of the photon-pressure actuator having four beams independently controlled and applied it to CHRONOS experiment. Based on a realistic power control system, we estimated its maximum torque amplitude around yaw rotation axis as 1.0×10 -8 N•m and actuation efficiency as 6.6×10 -13 rad/V, which are sufficiently large for controlling the CHRONOS torsion bar. The actuation noise was estimated as 5.3×10 -19 rad•Hz -1/2 at 1 Hz, lower than the target sensitivity of CHRONOS. Assuming its usage as a photon calibrator, the estimated systematic error was 1.14%.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"11 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-09DOI: 10.1088/1361-6382/aeb25a
An T. Le
Abstract Energy-condition tests for warp-drive spacetimes must account for all admissible causal directions at each point. We use the classical S-lemma to express the null, weak and strong conditions as 4×4 linear matrix inequalities; the dominant condition requires two such tests. These criteria require neither Hawking–Ellis classification nor a rapidity cutoff. For the null condition in a fixed orthonormal tetrad, the optimized multiplier margin equals half the minimum normalized null-energy contraction. Interval evaluation of the metric and curvature provides pointwise certificates and global bounds on its minimum over the bubble wall. On flat unit-lapse slices, the momentum constraint relates Eulerian momentum to shift vorticity. For smooth shifts on all of Euclidean space with bounded vorticity, momentum vanishes identically precisely for a gradient plus rigid rotation. For shifts linear in speed, integrated negative Eulerian energy scales exactly quadratically when finite, with a fixed profile and integration domain on these slices. We implement the tests in warpax, a JAX toolkit, and compare four warp-drive geometries at matched parameters across subluminal and superluminal speeds. At the reference parameters, the global bounds establish null-energy violation in all four bubble walls. The ideal irrotational Rodal profile has zero Eulerian momentum and is everywhere Type I; Type-IV regions are detected in the other sampled walls. For Rodal, the Eulerian reading misses about 73% of the sampled wall weak-energy violations. These numerical type labels and sampled fractions are distinct from the interval bounds. Finite-segment null-geodesic integrals and flat-space quantum-inequality estimates supplement the pointwise analysis.
{"title":"Observer-robust energy condition verification for warp drive spacetimes","authors":"An T. Le","doi":"10.1088/1361-6382/aeb25a","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb25a","url":null,"abstract":"Abstract Energy-condition tests for warp-drive spacetimes must account for all admissible causal directions at each point. We use the classical S-lemma to express the null, weak and strong conditions as 4×4 linear matrix inequalities; the dominant condition requires two such tests. These criteria require neither Hawking–Ellis classification nor a rapidity cutoff. For the null condition in a fixed orthonormal tetrad, the optimized multiplier margin equals half the minimum normalized null-energy contraction. Interval evaluation of the metric and curvature provides pointwise certificates and global bounds on its minimum over the bubble wall. On flat unit-lapse slices, the momentum constraint relates Eulerian momentum to shift vorticity. For smooth shifts on all of Euclidean space with bounded vorticity, momentum vanishes identically precisely for a gradient plus rigid rotation. For shifts linear in speed, integrated negative Eulerian energy scales exactly quadratically when finite, with a fixed profile and integration domain on these slices. We implement the tests in warpax, a JAX toolkit, and compare four warp-drive geometries at matched parameters across subluminal and superluminal speeds. At the reference parameters, the global bounds establish null-energy violation in all four bubble walls. The ideal irrotational Rodal profile has zero Eulerian momentum and is everywhere Type I; Type-IV regions are detected in the other sampled walls. For Rodal, the Eulerian reading misses about 73% of the sampled wall weak-energy violations. These numerical type labels and sampled fractions are distinct from the interval bounds. Finite-segment null-geodesic integrals and flat-space quantum-inequality estimates supplement the pointwise analysis.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-09DOI: 10.1088/1361-6382/aeb29c
Yoann Launay
Abstract During cosmological inflation, inhomogeneities arising from quantum vacuum fluctuations are stretched to become super-Hubble and effectively classical. As many scenarios of the origin involve nonlinearities or a breakdown of perturbativity in the infrared, the limitations of quantum field theory can be addressed using a stochastic description of the dynamics, the so-called stochastic inflation paradigm. However, the stochastic formalism was only recently formulated consistently within full General Relativity and has not yet been extended to more general theories of the early universe, which is the subject of this work.
In order to find the stochastic sources for a wide class of fully nonlinear scalar-tensor theories, we apply our gauge-agnostic coarse-graining procedure to the linear equations of the yl{associated effective field theory}. Each theory can then be mapped to its own set of stochastic equations of motion by identifying the corresponding coefficients in the yl{former}. We illustrate this with a few concrete and, in most cases, unprecedented examples, including Gauss-Bonnet, generalized Brans-Dicke, Horndeski, and braiding theories.
Finally, we discuss other natural extensions to provide a phenomenologically complete stochastic framework. For example, we showcase the coarse-graining of multifield inflation in full General Relativity and argue for the generality of our procedure and thus its potential applications beyond the realm of inflation.
{"title":"Stochastic scalar-tensor inflation and beyond","authors":"Yoann Launay","doi":"10.1088/1361-6382/aeb29c","DOIUrl":"https://doi.org/10.1088/1361-6382/aeb29c","url":null,"abstract":"Abstract During cosmological inflation, inhomogeneities arising from quantum vacuum fluctuations are stretched to become super-Hubble and effectively classical. As many scenarios of the origin involve nonlinearities or a breakdown of perturbativity in the infrared, the limitations of quantum field theory can be addressed using a stochastic description of the dynamics, the so-called stochastic inflation paradigm. However, the stochastic formalism was only recently formulated consistently within full General Relativity and has not yet been extended to more general theories of the early universe, which is the subject of this work.
In order to find the stochastic sources for a wide class of fully nonlinear scalar-tensor theories, we apply our gauge-agnostic coarse-graining procedure to the linear equations of the yl{associated effective field theory}. Each theory can then be mapped to its own set of stochastic equations of motion by identifying the corresponding coefficients in the yl{former}. We illustrate this with a few concrete and, in most cases, unprecedented examples, including Gauss-Bonnet, generalized Brans-Dicke, Horndeski, and braiding theories.
Finally, we discuss other natural extensions to provide a phenomenologically complete stochastic framework. For example, we showcase the coarse-graining of multifield inflation in full General Relativity and argue for the generality of our procedure and thus its potential applications beyond the realm of inflation.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"42 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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