Geoffrey Lovelace, Kyle C Nelli, Nils Deppe, Nils L Vu, William Throwe, Marceline S Bonilla, Alexander Carpenter, Lawrence E Kidder, Alexandra Macedo, Mark A Scheel, Azer Afram, Michael Boyle, Andrea Ceja, Matthew Giesler, Sarah Habib, Ken Z Jones, Prayush Kumar, Guillermo Lara, Denyz Melchor, Iago B Mendes, Keefe Mitman, Marlo Morales, Jordan Moxon, Eamonn O’Shea, Kyle Pannone, Harald P Pfeiffer, Teresita Ramirez-Aguilar, Jennifer Sanchez, Daniel Tellez, Saul A Teukolsky and Nikolas A Wittek
{"title":"Simulating binary black hole mergers using discontinuous Galerkin methods","authors":"Geoffrey Lovelace, Kyle C Nelli, Nils Deppe, Nils L Vu, William Throwe, Marceline S Bonilla, Alexander Carpenter, Lawrence E Kidder, Alexandra Macedo, Mark A Scheel, Azer Afram, Michael Boyle, Andrea Ceja, Matthew Giesler, Sarah Habib, Ken Z Jones, Prayush Kumar, Guillermo Lara, Denyz Melchor, Iago B Mendes, Keefe Mitman, Marlo Morales, Jordan Moxon, Eamonn O’Shea, Kyle Pannone, Harald P Pfeiffer, Teresita Ramirez-Aguilar, Jennifer Sanchez, Daniel Tellez, Saul A Teukolsky and Nikolas A Wittek","doi":"10.1088/1361-6382/ad9f19","DOIUrl":"https://doi.org/10.1088/1361-6382/ad9f19","url":null,"abstract":"Binary black holes are the most abundant source of gravitational-wave observations. Gravitational-wave observatories in the next decade will require tremendous increases in the accuracy of numerical waveforms modeling binary black holes, compared to today’s state of the art. One approach to achieving the required accuracy is using spectral-type methods that scale to many processors. Using the SpECTRE numerical-relativity (NR) code, we present the first simulations of a binary black hole inspiral, merger, and ringdown using discontinuous Galerkin (DG) methods. The efficiency of DG methods allows us to evolve the binary through ∼ 18 orbits at reasonable computational cost. We then use SpECTRE’s Cauchy Characteristic Evolution (CCE) code to extract the gravitational waves at future null infinity. The open-source nature of SpECTRE means this is the first time a spectral-type method for simulating binary black hole evolutions is available to the entire NR community.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"82 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935229","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}
Akihito Katsumata, Tomohiro Harada, Kota Ogasawara and Hayami Iizuka
{"title":"New series expansion for the periapsis shift","authors":"Akihito Katsumata, Tomohiro Harada, Kota Ogasawara and Hayami Iizuka","doi":"10.1088/1361-6382/ada196","DOIUrl":"https://doi.org/10.1088/1361-6382/ada196","url":null,"abstract":"We propose a prescription for a new series expansion of the periapsis shift. The prescription formulates the periapsis shift in various spacetimes analytically without using special functions and provides simple and highly accurate approximate formulae. We derive new series representations for the periapsis shift in the Kerr and the Chazy–Curzon spacetimes by using the prescription, where the expansion parameter is defined as the eccentricity divided by the non-dimensional quantity that vanishes in the limit of the innermost stable circular orbit (ISCO). That is to say, the expansion parameter characterizes both the eccentricity of the orbit and its proximity to the ISCO. The smaller the eccentricity, the higher the accuracy of the formulae that are obtained by truncating the new series representations up to a finite number of terms. If the eccentricity is sufficiently small, the truncated new representations have higher accuracy than the post-Newtonian (PN) expansion formulae even in strong gravitational fields where the convergence of the PN expansion formula is not guaranteed. On the other hand, even if the orbit is highly eccentric, the truncated new representations have comparable or higher accuracy than the PN expansion formulae if the semi-major axis is sufficiently large. An exact formula for the periapsis shift of the quasi-circular orbit in the Chazy–Curzon spacetime is also obtained as a special case of the new series representation.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"12 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935230","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":"Gyroscopic gravitational memory from quasi-circular binary systems","authors":"Guillaume Faye and Ali Seraj","doi":"10.1088/1361-6382/ada339","DOIUrl":"https://doi.org/10.1088/1361-6382/ada339","url":null,"abstract":"Gravitational waves cause freely falling spinning objects to precess, resulting in a net orientation change called gyroscopic memory. In this paper, we will consider isolated gravitational sources in the post-Newtonian (PN) framework and compute the gyroscopic precession and memory at leading PN orders. We compare two competing contributions: the spin memory and the nonlinear helicity flux. At the level of the precession rate, the former is a 2PN oscillatory effect, while the latter is a 4PN adiabatic effect. However, the gyroscopic memory involves a time integration, which enhances subleading adiabatic effects by the fifth power of the velocity of light, leading to a 1.5PN memory effect. We explicitly compute the leading effects for a quasi-circular binary system and obtain the angular dependence of the memory on the celestial sphere.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"310 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935233","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}
Zihan Wang, Yanfu Liu, Xida Han, Yuntao Cheng, Ming Li and Hongchao Zhao
{"title":"Dimensional stability sensitivity analysis based on transfer function models for telescope in space gravitational wave detectors","authors":"Zihan Wang, Yanfu Liu, Xida Han, Yuntao Cheng, Ming Li and Hongchao Zhao","doi":"10.1088/1361-6382/ada2d2","DOIUrl":"https://doi.org/10.1088/1361-6382/ada2d2","url":null,"abstract":"The telescope serves as a vital component of the space gravitational wave detector. In TianQin project, the exceptional dimensional stability of the telescope must be better than 1 pm Hz−1/2 @0.1 mHz–1 Hz. To assess the in-orbit dimensional stability of the telescope, a transfer function model was developed to evaluate the stability of the primary and secondary mirror spacing structure, considering the three primary thermal sources. It has been discovered that the stability of the spacer structure is influenced not only by the thermal expansion coefficient of the material but also by its heat capacity, density, and frequency band. Zerodur offers distinct advantages in terms of overall thermal performance. Specifically, the stability of the spacer constructed by it can be effectively controlled at 0.14 pm Hz−1/2@0.1 mHz–1 Hz, which is an achievement in the field of ultra-stability structure design.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"28 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935234","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}
Alessio Belfiglio, Orlando Luongo, Stefano Mancini and Sebastiano Tomasi
{"title":"Entanglement entropy in quantum black holes","authors":"Alessio Belfiglio, Orlando Luongo, Stefano Mancini and Sebastiano Tomasi","doi":"10.1088/1361-6382/ad9e66","DOIUrl":"https://doi.org/10.1088/1361-6382/ad9e66","url":null,"abstract":"We discuss the entanglement entropy for a massive scalar field in two Schwarzschild-like quantum black hole spacetimes, also including a nonminimal coupling term with the background scalar curvature. To compute the entanglement entropy, we start from the standard spherical shell discretization procedure, tracing over the degrees of freedom residing inside an imaginary surface. We estimate the free parameters for such quantum metrics through a simple physical argument based on Heisenberg uncertainty principle, along with alternative proposals as asymptotic safety, trace anomaly, and graviton corpuscular scaling. Our findings reveal a significant decrease in entropy compared to the area law near the origin for the quantum metrics. In both scenarios, the entanglement entropy converges to the expected area law sufficiently far from the origin. We then compare these results to the entropy scaling in regular Hayward and corrected-Hayward spacetimes to highlight the main differences with such regular approaches.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"32 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935227","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":"Phase space structure of symmetric teleparallel theory of gravity","authors":"Dalia Saha and Abhik Kumar Sanyal","doi":"10.1088/1361-6382/ada197","DOIUrl":"https://doi.org/10.1088/1361-6382/ada197","url":null,"abstract":"The ‘generalized symmetric teleparallel gravity’ (GSTG) does not admit diffeomorphic invariance, since the auxiliary field as well as the shift vector act as non-propagating dynamical variables carrying 1/2 degrees of freedom each. We show that in a minisuperspace model, which is devoid of the shift vector, the problem is alleviated for locally Lorentz invariant GSTG theory, and diffeomorphic invariance is established at least for one connection. However, the eerie structure of the Hamiltonian constructed even in the background of spatially flat isotropic and homogeneous Robertson–Walker space-time, can not be maneuvered. In contrast, the other two spatially flat connections containing an arbitrary time dependent function, doesʼnt admit non-linear extension to ‘symmetric teleparallel equivalent to general relativity’ (STEGR). We therefore construct the phase-space structure with three different spatially flat connections for the ‘Lorentz invariant’ linear-scalar–vector–tensor GSTG action. Diffeomorphic invariance is established and the associated Hamiltonians are found to be well behaved for all the three cases.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"98 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935232","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":"3+1 formalism of the minimally extended varying speed of light model","authors":"Seokcheon Lee","doi":"10.1088/1361-6382/ada2d5","DOIUrl":"https://doi.org/10.1088/1361-6382/ada2d5","url":null,"abstract":"The formalism provides a structured approach to analyzing spacetime by separating it into spatial and temporal components. When applied to the Robertson–Walker metric, it simplifies the analysis of cosmological evolution by dividing the Einstein field equations into constraint and evolution equations. It introduces the lapse function N and the shift vector Ni, which control how time and spatial coordinates evolve between hypersurfaces. In standard model cosmology, N = 1 and for the Robertson–Walker metric. However, the N becomes a function of time when we apply the metric to the minimally extended varying speed of light model. This approach allows for a more direct examination of the evolution of spatial geometry and offers flexibility in handling scenarios where the lapse function and shift vector vary. In this manuscript, we derive the model's N, Ni, along with the constraint and evolution equations, and demonstrate their consistency with the existing Einstein equations. We have shown in a previous paper that the possibility of changes in the speed of light in the Robertson–Walker metric is due to cosmological time dilation. Through the formalism, we can make the physical significance more explicit and demonstrate that it can be interpreted as the lapse function. From this, we show that the minimally extended varying speed of light model is consistent.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"38 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929583","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":"Some remarks on Wang–Yau quasi-local mass","authors":"Bowen Zhao, Lars Andersson and Shing-Tung Yau","doi":"10.1088/1361-6382/ada1c1","DOIUrl":"https://doi.org/10.1088/1361-6382/ada1c1","url":null,"abstract":"We review the definition of Wang–Yau quasi-local mass from the point of view of the gravitational Hamiltonian. This makes clear the relation between Wang–Yau definition and Brown–York or even global ADM definition. We make a brief comment on admissibility condition in the definition of the Wang–Yau quasi-lcoal mass. We extend the positivity proof for Wang–Yau quasi-local energy to allow possible presence of strictly stable apparent horizons through establishing solvability of Dirac equation in certain 3-manifolds that possess cylindrical ends, as in the case of Jang graph blowing up at marginally outer trapped surfaces.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"37 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929573","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":"A nested sequence of inequivalent Rindler vacua : universal relic thermality of Planckian origin","authors":"Kinjalk Lochan and T Padmanabhan","doi":"10.1088/1361-6382/ada2d6","DOIUrl":"https://doi.org/10.1088/1361-6382/ada2d6","url":null,"abstract":"The Bogoliubov transformation connecting the standard inertial frame mode functions to the standard mode functions defined in the Rindler frame R0, leads to the result that the inertial vacuum appears as a thermal state with temperature where a0 is the acceleration parameter of R0. We construct an infinite family of nested Rindler-like coordinate systems within the right Rindler wedge, with time coordinates and acceleration parameters by shifting the origin along the inertial x-axis by amounts . We show that, apart from the inertial vacuum, the Rindler vacuum of the frame Rn also appears to be a thermal state in the frame with the temperature . In fact, the Rindler frame attributes to all the Rindler vacuum states of , as well as to the inertial vacuum state, the same temperature . We further show that our result is discontinuous in an essential way in the coordinate shift parameters. For a Rindler frame Ri, this thermality turns on with smallest non-zero allowed in the semiclassical framework and remains insensitive to thereafter, indicating its universal Planckian origin. Similar structures can be introduced in the right wedge of any spacetime with bifurcate Killing horizon, like, for e.g. Schwarzschild spacetime. Apart from providing unsuppressed observables capturing Planck scale effects, these results have important implications for quantum gravity (QG) when flat spacetime is treated as the ground state of QG. Furthermore, a frame with the shift and the corresponding acceleration parameter can be thought of as a Rindler frame which is instantaneously comoving with the Einstein's elevator moving with a variable acceleration. Our result suggests that the quantum temperature associated with such an Einstein's elevator is the same as that defined in the comoving Rindler frame. The implications of these results are wide ranging, from having a definitive signature of Planck shifts in the horizon to the existence of a new set of observers in black hole exterior having thermodynamic description of the horizon they perceive.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"27 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929639","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":"Entropy production due to spacetime fluctuations","authors":"Thiago H Moreira and Lucas C Céleri","doi":"10.1088/1361-6382/ada083","DOIUrl":"https://doi.org/10.1088/1361-6382/ada083","url":null,"abstract":"Understanding the quantum nature of the gravitational field is undoubtedly one of the greatest challenges in theoretical physics. Despite significant progress, a complete and consistent theory remains elusive. However, in the weak field approximation—where curvature effects are small—we can explore some expected properties of such a theory. Particularly relevant to this study is the quantum nature of gravitational waves, which are represented as small perturbations in flat spacetime. In this framework, a quantum description of these perturbations, as a quantum field, is feasible, leading to the emergence of the graviton. Here we consider a non-relativistic quantum system interacting with such a field. We employ the consistent histories approach to quantum mechanics, which allows us to frame classical questions in a quantum context, to define a fluctuation relation for this system. As a result, thermodynamic entropy must be produced in the system due to its unavoidable interaction with the quantum fluctuations of spacetime.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"3 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905019","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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