{"title":"Hermiticity/factor-ordering duality in quantum black holes","authors":"Harpreet Singh and Malay K Nandy","doi":"10.1088/1361-6382/add5b6","DOIUrl":"https://doi.org/10.1088/1361-6382/add5b6","url":null,"abstract":"As the property of duality exists in various disciplines of physics since early times, it is important to look for the existence of this symmetry in the physics of black holes described by quantum gravity. While canonically quantizing gravity, it is well-known that ambiguity in operator ordering and the requirement of Hermiticity play their crucial roles in determining the wave function of the black hole interior. Consequently, it is important to look for how Hermiticity and operator ordering could be interrelated, presumably by means of some duality between the two. In order to study this feature in a concrete way, we consider in this paper two distinct Kantowski–Sachs minisuperspace models for the black hole interior. In the process of canonical quantization in the first model, we maintain Hermiticity in the ensuing Wheeler–DeWitt equation. On the other hand, in the second model, we do not impose Hermiticity, but consider a general operator ordering in the Wheeler–DeWitt equation. Despite these crucial differences in the two frameworks, we find that there exists an exact duality between the wave functions occurring as solutions of the Wheeler–DeWitt equations in the two scenarios, called herein Hermiticity/factor-ordering duality.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066688","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":"Beyond GWTC-3: analyzing and verifying new gravitational-wave events from community catalogues","authors":"Daniel Williams","doi":"10.1088/1361-6382/add233","DOIUrl":"https://doi.org/10.1088/1361-6382/add233","url":null,"abstract":"The public release of data from the LIGO and Virgo detectors has enabled the identification of potential gravitational wave signals by independent teams using alternative methodologies. In addition to the LIGO-Virgo-KAGRA (LVK) collaboration’s GWTC-3 catalogue there have been several additional works claiming the detection of signals in the data from the first three observing runs. In this paper we present an analysis of these new signals using the same analysis workflow which was used to generate the GWTC-2.1 and GWTC-3 catalogues published by the LVK, matching the analysis configuration as closely as possible, and we provide our parameter estimation results in a format comparable to those of the GWTC-3 data release for 57 events not previously analyzed in LVK analyses. We find our results to be broadly consistent with those published by other groups. We also include a discussion of the workflow developed for this analysis.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"52 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979529","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":"Demonstration of tilt sensing using a homodyne quadrature interferometric translational sensor","authors":"Koji Nagano, Karera Mori and Kiwamu Izumi","doi":"10.1088/1361-6382/add3b4","DOIUrl":"https://doi.org/10.1088/1361-6382/add3b4","url":null,"abstract":"Future gravitational wave observation in space will demand improvement in the sensitivity of the local sensor for the drag-free control. This paper presents the proposal, design, and demonstration of a new laser interferometric sensor named Quadrature Interferometric Metrology of Translation and Tilt (QUIMETT) for the drag-free local sensor. QUIMETT enables simultaneous measurements of both translational displacement and tilts of a reflective object with a single interferometer package. QUIMETT offers a characteristic feature where the sensitivity to tilt is independent of the interference condition while maintaining the ability to measure the translational displacement for a range greater than the laser wavelength. The tilt-sensing function has been demonstrated in a prototype experiment. The tilt sensitivity remained unchanged in different interference conditions and stayed at 10 nrad Hz at 0.1 Hz.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"29 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945919","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}
Christopher Alléné, Florian Aubin, Inès Bentara, Damir Buskulic, Gianluca M Guidi, Vincent Juste, Morgan Lethuillier, Frédérique Marion, Lorenzo Mobilia, Benoît Mours, Amazigh Ouzriat, Thomas Sainrat and Viola Sordini
{"title":"The MBTA pipeline for detecting compact binary coalescences in the fourth LIGO-Virgo-KAGRA observing run","authors":"Christopher Alléné, Florian Aubin, Inès Bentara, Damir Buskulic, Gianluca M Guidi, Vincent Juste, Morgan Lethuillier, Frédérique Marion, Lorenzo Mobilia, Benoît Mours, Amazigh Ouzriat, Thomas Sainrat and Viola Sordini","doi":"10.1088/1361-6382/add234","DOIUrl":"https://doi.org/10.1088/1361-6382/add234","url":null,"abstract":"In this paper, we describe the multi-band template analysis search pipeline dedicated to the detection of compact binary coalescence gravitational wave signals from the data obtained by the LIGO-Virgo-KAGRA collaboration during the fourth observing run (O4), which started in May 2023. We give details on the configuration of the pipeline and its evolution compared to the third observing run (O3). We focus here on the configuration used for the offline results of the first part of the run (O4a), which are part of the GWTC-4 catalog (in preparation). We also give a brief summary of the online configuration and highlight some of the changes implemented or considered for the second part of O4 (O4b).","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"55 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945918","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":"Using t-SNE for characterizing glitches in LIGO detectors","authors":"Tabata Aira Ferreira and Gabriela González","doi":"10.1088/1361-6382/add3b5","DOIUrl":"https://doi.org/10.1088/1361-6382/add3b5","url":null,"abstract":"Glitches are non-Gaussian noise transients originating from environmental and instrumental sources that contaminate data from gravitational wave detectors. Some glitches can even mimic gravitational wave signals from compact object mergers, which are the primary targets of terrestrial observatories. In this study, we present a method to analyze noise transients from the Laser Interferometer Gravitational-Wave Observatory observatories using Q-transform information combined with t-distributed stochastic neighbor embedding. We implement classification techniques, examine the influence of parameters on glitch classification, and conduct a week-long daily analysis to track outlier transients over time.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"39 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945696","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":"Gravitational energy creation in the sandwich pp-waves collision","authors":"F L Carneiro and K Q Abbasi","doi":"10.1088/1361-6382/add2c7","DOIUrl":"https://doi.org/10.1088/1361-6382/add2c7","url":null,"abstract":"This article investigates the spacetime of two colliding sandwich gravitational waves, focusing on evaluating gravitational energy before and after the collision. In the framework of the teleparallel equivalent of general relativity (TEGR), we derive a true energy–momentum tensor for the gravitational waves and integrate it over a finite region of space, obtaining analytical expressions for the energy of each wave and the resulting spacetime. Our findings reveal that the energy after the collision exceeds the pre-collision, indicating energy creation. We analyze the energy density and ‘surface energy density’ on the wavefronts, underscoring their divergence near the singularity. Additionally, we observe that the colliding waves drag observers but exert no acceleration at the collision event. This study addresses and resolves longstanding issues raised by Szekeres in his seminal work on colliding pp-waves, offering a more physically realistic framework through the local energy definition provided by TEGR. The implications for gravitational wave interactions and their energy transfer mechanisms are discussed.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"231 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945962","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}
Astrid Eichhorn, Pedro G S Fernandes, Aaron Held and Hector O Silva
{"title":"Breaking black-hole uniqueness at supermassive scales","authors":"Astrid Eichhorn, Pedro G S Fernandes, Aaron Held and Hector O Silva","doi":"10.1088/1361-6382/add3b6","DOIUrl":"https://doi.org/10.1088/1361-6382/add3b6","url":null,"abstract":"In general relativity (GR), all asymptotically flat, stationary and axisymmetric vacuum black holes are described by the Kerr solution. Beyond GR, there is a prevailing expectation that deviations from the Kerr solution increase with the horizon curvature. We challenge this expectation by showing that, in a scalar-Gauss–Bonnet theory, black holes scalarize in a finite, adjustable window of black-hole masses, bounded from above and below. In this theory, there is an interplay between curvature scales and compactness, which we expect to protect neutron stars and other less compact objects from scalarization. In addition, this theory is the first to avoid the catastrophic instability of early-Universe cosmology that affects previous scalarization models. In this theory, black-hole uniqueness can be broken at supermassive black-hole scales, while stellar-mass black holes remain well-described by the general relativistic solution. To probe this scenario, observations targeting supermassive black holes are necessary.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"4 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945920","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":"Detecting horizons of symmetric black holes using relative differential invariants","authors":"David McNutt and Eivind Schneider","doi":"10.1088/1361-6382/adcc72","DOIUrl":"https://doi.org/10.1088/1361-6382/adcc72","url":null,"abstract":"Let be a nontrivial finite-dimensional Lie algebra of vector fields on a manifold M, and consider the family of Lorentzian metrics on M whose Killing algebra contains . We show that scalar relative differential invariants of such metrics, with respect to a Lie algebra of vector fields on M preserving , can be used to detect the horizons of several well-known black holes. In particular, using the Lie algebra structure of , we construct a general relative differential invariant of order 0 that always vanishes on -invariant Killing horizons. While the current work is meant to demonstrate the relevance of jet bundles and relative differential invariants in physical applications, we also provide a computationally simple approach for finding a relative differential invariant that detects Killing horizons. The computation and use of this relative differential invariant is comparable in difficulty to other horizon detection methods when there is an obvious Killing vector field that generates the Killing horizon, and often simpler when the preferred Killing vector field is not obvious.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"32 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143945916","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":"Instability of slowly expanding FLRW spacetimes","authors":"Elliot Marshall","doi":"10.1088/1361-6382/add2c8","DOIUrl":"https://doi.org/10.1088/1361-6382/add2c8","url":null,"abstract":"We numerically study, under a Gowdy symmetry assumption, nonlinear perturbations of the decelerated FLRW fluid solutions to the Einstein–Euler system toward the future for linear equations of state with . This article builds on the work of Fajman et al (2024 arXiv:2405.03431) in which perturbations of the homogeneous fluid solution on a fixed, decelerating FLRW background were studied. Our numerical results show that for all values of K, perturbations of the FLRW solution develop shocks in finite time. This behaviour contrasts known results for spacetimes with accelerated expansion in which shock formation is suppressed.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"72 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927283","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}
Bing-Wei Cai, Chao Xue, Ji Wang, Di-Wen Shi, Jie Chang, Wei Wang and Yi-Yan Xu
{"title":"Analytical model of Johnson–Kendall–Roberts adhesive contact with coating roughness on the release of test mass in TianQin","authors":"Bing-Wei Cai, Chao Xue, Ji Wang, Di-Wen Shi, Jie Chang, Wei Wang and Yi-Yan Xu","doi":"10.1088/1361-6382/add2c9","DOIUrl":"https://doi.org/10.1088/1361-6382/add2c9","url":null,"abstract":"The surface of the coating or substrate structure has a rough topological structure over multiple scales, which significantly affects the actual contact area and adhesion strength. In order to investigate potential interferences during the test mass (TM) release process of the locking and release mechanism in TianQin space-borne gravitational wave detection project, an analytical model of the Johnson–Kendall–Roberts (JKR) adhesive contact with coating roughness between the TM and the release tip has been developed. This work presents the integration of the JKR theory with the Greenwood–Williamson rough surface contact theory to address adhesion challenges and influence of roughness in space-borne gravitational wave detection systems. The comprehensive model can be used to analyze how various factors such as surface shape, material properties, coating thickness and roughness affect adhesion. By introducing a numerical approach based on the Newton down-hill method to solve coupled equations for gap, stress, and load balance, the model achieves high-precision predictions of adhesion behavior under multi-scale roughness effects. By establishing relationships between force, contact half-width, and penetration depth, it provides a theoretical basis for optimizing the TM release process and the design of the locking and release mechanism. Future work will validate predictions via high-precision torsion pendulum experiments.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"118 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927284","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}