Classical and Quantum Gravity最新文献

{"title":"S-algebra in gauge theory: twistor, spacetime and holographic perspectives","authors":"Adam Kmec, Lionel Mason, Romain Ruzziconi and Atul Sharma","doi":"10.1088/1361-6382/ae0673","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0673","url":null,"abstract":"The celestial S-algebra arose from a reinterpretation of collinear limits of the Yang–Mills S-matrix as OPEs in celestial holography. It was subsequently represented via asymptotic charge aspects defined in the Yang–Mills radiative phase space defined at null infinity on the one hand, and via a twisted holography vertex algebra construction in twistor space on the other. Here we first identify it with the traditional symmetry algebra of self-dual Yang–Mills theory as an integrable system via its hierarchies of conserved quantities and associated flows; the self-dual phase space can be canonically identified with that of full Yang–Mills at null infinity . We derive the associated canonical generators from the twistor space action, identifying two infinite towers of charges corresponding to the two gluon helicities. These expressions are translated into spacetime data at null infinity using twistor integral formulae. Examining the charge algebra at spacelike infinity reveals the vertex algebras studied in the context of twisted holography. Our discussion extends directly to the celestial symmetries of self-dual gravity. This analysis provides a unified framework for celestial symmetries, connecting twistor, spacetime, and holographic approaches and culminating in a nonlinear extrapolate dictionary for self-dual gauge theory.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127543","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}

{"title":"Canonical gravity in degenerate limit","authors":"Sandipan Sengupta","doi":"10.1088/1361-6382/ae06ea","DOIUrl":"https://doi.org/10.1088/1361-6382/ae06ea","url":null,"abstract":"We construct a limit of Hamiltonian gravity as the determinant of the spatial triad (and hence of the four-metric) goes to zero. Within the Barbero–Immirzi SU(2) formulation, we present two possible realizations of this limit, with the consequence that the Hamiltonian constraint becomes simpler and spatial diffeomorphisms become trivial. In the first case, the Hamiltonian constraint exhibits a polynomial structure, being formally similar to the Euclidean Hamitonian constraint of Sen–Ashtekar self-dual formulation. In the latter, the constraints become free from ordering ambiguity. Further, we show that the Carrollian gravity emerges as a special case of this degenerate limit, thus providing it a new geometric interpretation independent of the speed of light or any dimensionful coupling constant (G).","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"40 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145127544","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}

{"title":"Can an extra degree of freedom in scalar-tensor non-metricity gravity account for the evolution of the Universe?","authors":"Ghulam Murtaza, Avik De, Andronikos Paliathanasis and Tee-How Loo","doi":"10.1088/1361-6382/ae0404","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0404","url":null,"abstract":"We investigate whether the extra scalar degree of freedom that arises in the second connection class of scalar-tensor non-metricity gravity can accurately replicate and potentially enrich the cosmic expansion history. Focusing on a spatially flat Friedmann–Lemaître–Robertson–Walker background, we introduce Hubble-normalized variables and recast the field equations into an autonomous dynamical system. Four representative scenarios are analyzed comprehensively. Phase-space research reveals a rich hierarchy of critical points: matter-dominated, stiff-fluid, and de Sitter solutions, together with asymptotic trajectories leading to Big-Crunch/Rip singularities and transient, unstable matter epochs. With suitable parameter choices, the standard ΛCDM sequence is reinstated; however, novel late-time and high-curvature regimes arise exclusively from the non-metricity sector. A systematic comparison of metric scalar-tensor and teleparallel scalar-torsion theories reveals unique stability characteristics and potential observational discriminants. Our findings indicate that the additional time-dependent function inherent to scalar-tensor non-metricity gravity can effectively explain the Universe’s evolution while providing new phenomenology that can be tested by upcoming surveys.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"35 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116361","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}

{"title":"Listening across the cosmic time: standard sirens from ground- and space-based missions in the next decade","authors":"Alberto Salvarese, Hsin-Yu Chen, Alberto Mangiagli and Nicola Tamanini","doi":"10.1088/1361-6382/ae05ab","DOIUrl":"https://doi.org/10.1088/1361-6382/ae05ab","url":null,"abstract":"Precise measurement of the Hubble parameter will enable stringent tests of the standard model for cosmology. Standard sirens, using the luminosity distances measured by gravitational-wave observations of compact binary mergers, are expected to provide such measurements independently in the next decade. With the ground- and space-based gravitational wave observatories, the LIGO-Virgo-KAGRA (LVK) network and the Laser Interferometer Space Antenna (LISA), different types of standard sirens altogether will place constraints across a wide redshift range. In this paper, we forecast the precisions of standard siren Hubble parameter measurements and compare various scenarios, accounting for the dominant sources of systematic uncertainty. Specifically, we find a 2% constraint on H0, a 1.5%−3% constraint on H(z) at z = 1, and a 3%−5% constraint on H(z) at z = 7 when combining LVK and LISA standard sirens with precise redshift measurements from electromagnetic (EM) counterpart observations. We do not find a significant improvement when including standard sirens with no EM counterpart, but which rely on features in the black hole mass distribution, and the potential systematics introduced by the possible redshift evolution of such features could further degrade the measurement accuracy if not properly accounted for.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"17 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116363","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}

{"title":"Hyperboloidal neutron star and black hole initial data in spherical symmetry","authors":"Alex Vañó-Viñuales","doi":"10.1088/1361-6382/ae05e4","DOIUrl":"https://doi.org/10.1088/1361-6382/ae05e4","url":null,"abstract":"The focus of this work is on the construction of initial data including a neutron star on a hyperboloidal slice. As simplest scenario for this first step, spherical symmetry is considered together with a polytropic-like equation of state for the neutron star. Constraint-satisfying hyperboloidal initial data are obtained for a single neutron star and for a combination of neutron star with a black hole in its center. To the author’s best knowledge this is the first time that full hyperboloidal slices of a neutron star spacetime are constructed. The obtained initial data are suitable for evolutions of the Einstein and relativistic hydrodynamic equations on hyperboloidal slices.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"90 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116364","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}

{"title":"Towards a spacelike characterization of the null singularity inside a black hole","authors":"David Garfinkle","doi":"10.1088/1361-6382/ae0387","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0387","url":null,"abstract":"We propose a method for recognizing null singularities in a computer simulation that uses a foliation by spacelike surfaces. The method involves harmonic time slicing as well as rescaled tetrad variables. As a ‘proof of concept’ we show that the method works in Reissner–Nordstrom spacetime.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116360","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}

{"title":"Conformal boundaries near extremal black holes","authors":"Damián A Galante, Chawakorn Maneerat and Andrew Svesko","doi":"10.1088/1361-6382/ae0408","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0408","url":null,"abstract":"We examine four dimensional, near-extremal black hole solutions in the presence of a finite boundary obeying conformal boundary conditions, where the conformal class of the induced metric and the trace of the extrinsic curvature are fixed. Working in Euclidean signature and at fixed charge, we find the near-extremal regime is dominated by a double-scaling limit which reveals new scaling laws for the quasi-local conformal entropy at low temperatures. Upon spherical dimensional reduction, we obtain the effective two-dimensional dilaton-gravity theory that describes the near-extremal regime. In contrast to Dirichlet boundaries, for conformal boundaries a linear dilaton potential is not sufficient to capture the leading correction away from extremality and higher orders are needed. We also examine near-Nariai solutions and the circular reduction of pure three-dimensional gravity in (Anti-) de Sitter space. In the latter, provided the boundary is placed near the conformal boundary of three-dimensional Anti-de Sitter space, the dynamics of the spherically symmetric boundary mode is governed by a Liouville equation that descends from a (minus) Schwarzian effective action.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"79 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116362","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}

{"title":"Multimode ringdown modeling with qnmfits and KerrRingdown","authors":"L Magaña Zertuche, L Gao, E Finch and G B Cook","doi":"10.1088/1361-6382/ae0233","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0233","url":null,"abstract":"Gravitational-wave astronomy is dominated by the study of the inspiral and ringdown phases of the signal. In the last decade, the ringdown community has made large strides in understanding the aftermath of binary black hole mergers through the study of numerical simulations. In this note, we introduce two flavors of fitting algorithms, that have been verified against each other, for the extraction of quasinormal mode amplitudes from ringdown waveforms - qnmfits in Python and KerrRingdown in Mathematica. In addition, these codes are able to simultaneously fit for the remnant mass and spin of the system. Different from other methods, we include a greedy algorithm that automatically chooses which modes to model based on their power content. These tools can be applied to any generic waveform, including those extracted using Cauchy-characteristic Evolution.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116309","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}

{"title":"Quantum geometry of the light cone: Fock representation and spectrum of radiated power","authors":"Wolfgang Wieland","doi":"10.1088/1361-6382/ae0235","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0235","url":null,"abstract":"Starting from the symplectic potential for the γ-Palatini–Holst action on a null hypersurface, we identify an auxiliary conformal field theory (CFT), which carries a representation of the constraint algebra of general relativity on a null surface. The radiative data, which is encoded into the shear of each null generator, is mapped into an current algebra on each light ray. We study the resulting quantum theory for both bosonic and fermionic representations. In the fermionic representation, the central charge on each null ray is positive, for bosons it is negative. A negative central charge implies a non-unitary CFT, which has negative norm states. In the model, there is a natural Casimir. For the bosonic representations, the Casimir can have either sign. For the fermionic representations, the Casimir is always greater or equal to zero. To exclude negative norm states, we restrict ourselves to the fermionic case. To understand the physical implications of this restriction, we express the Casimir in terms of the geometric data. In this way, the positivity bound on the Casimir translates into an upper bound for the shear of each null generator. In the model, this bound must be satisfied for all three-dimensional null hypersurfaces. This in turn suggests to apply it to an entire null foliation in an asymptotically flat spacetime. In this way, we obtain a bound on the radiated power of gravitational waves in the model.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"39 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116359","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}

{"title":"Performance of the KAGRA photon calibrators during the fourth joint observing run with LIGO and Virgo","authors":"Dan Chen, Shingo Hido, Darkhan Tuyenbayev, Dripta Bhattacharjee, Nobuyuki Kanda, Richard L Savage, Rishabh Bajpai, Sadakazu Haino, Takahiro Sawada, Takahiro Yamamoto, Takayuki Tomaru and Yoshiki Moriwaki","doi":"10.1088/1361-6382/adfcad","DOIUrl":"https://doi.org/10.1088/1361-6382/adfcad","url":null,"abstract":"The KAGRA detector, located in Kamioka, Japan, is a kilometer-scale cryogenic gravitational-wave (GW) interferometer. It joined the fourth joint observing run (O4) in May 2023 in collaboration with the Laser Interferometer GW Observatory (LIGO) in the USA and the Virgo observatory in Italy. After one month of observations, KAGRA entered a break period to enhance its sensitivity to GWs, and has rejoined O4 in June 2025, which is currently ongoing and planned to continue until November 2025. To accurately recover the information encoded in the GW signals, it is essential to properly calibrate the telescope output signals. A photon calibration (Pcal) system was employed as a reference displacement injector to calibrate the output signals obtained from the telescope. In this paper, we present the methods used to estimate the uncertainty in the Pcal systems employed at KAGRA during O4. We investigated and quantified the uncertainty in the Pcal laser power sensors, which had the highest impact on the Pcal uncertainty, and measured the beam positions on the KAGRA end mirror, which had the second highest impact. We report an estimated overall system uncertainty of 0.63%, which is more than a factor of four lower than the uncertainty achieved in the previous third joint observing run (O3) in 2020. This estimate included, for the first time, correction for the Pcal-induced apparent displacement caused by unintended rotation of the end test mass, based on measured beam positions on the mirror surface. The Pcal systems in KAGRA are the first fully functional calibration systems for a cryogenic GW telescope. To avoid interference with the KAGRA cryogenic systems, the Pcal systems incorporate unique features regarding their placement and the use of telephoto cameras, which can capture images of the mirror surface at almost normal incidence. These images are used to quantify the laser beam positions on the mirror surface enabling correction for the impact of unintended rotation of the mirror caused by Pcal forces. As future GW telescopes, such as the Einstein Telescope, are expected to adopt cryogenic techniques, the performance of the KAGRA Pcal systems can serve as a valuable reference.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"9 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078045","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}