Classical and Quantum Gravity最新文献

{"title":"B-spline based arm length estimation algorithm for space-borne gravitational wave detection","authors":"Defeng Gu, Zheng Zhang, Yangyu Ding and Chunbo Wei","doi":"10.1088/1361-6382/add2ca","DOIUrl":"https://doi.org/10.1088/1361-6382/add2ca","url":null,"abstract":"Data preprocessing is an essential step in space-borne gravitational wave detection, aimed at calibrating the data while suppressing noise. Time delay interferometry represents the primary technique for eliminating laser frequency noise, relying on precise arm length information. In this study, we combined pseudo-random noise ranging and Doppler measurements from TianQin’s data to create an observation equation and established an arm length model using a cubic B-spline function. To ensure accurate representation of the arm length and relative velocity, we employed quadruple-precision orbit information to simulate the observation data and determine reasonable spline node distances through fitting analysis. By utilizing the weighted least squares algorithm, we could estimate arm length information with millimeter-level accuracy. We investigated the contributions of the spline model’s smoothing function and additional Doppler measurement information to arm length estimation accuracy while analyzing the impact of weighting coefficients on the estimation results. Finally, we compared the accuracy of our proposed algorithm with that of the existing Kalman filter algorithm.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"108 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927329","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":"Testing general covariance in effective models motivated by loop quantum gravity","authors":"Juan Carlos Del Águila and Hugo A Morales-Técotl","doi":"10.1088/1361-6382/add079","DOIUrl":"https://doi.org/10.1088/1361-6382/add079","url":null,"abstract":"In this work we introduce a criterion for testing general covariance in effective quantum gravity theories. It adapts the analysis of invariance under general spacetime diffeomorphisms of the Einstein–Hilbert action to the case of effective canonical models. While the main purpose is to test models obtained in loop quantum gravity, the criterion is not limited to those physical systems and may be applied to any canonically formulated modified theory of gravity. The approach here is hence not that of finding an effective model, but rather to examine a given one represented by a quantum corrected Hamiltonian. Specifically, we will apply the criterion to spherically symmetric spacetimes in vacuum with inverse triad and holonomy modifications that arise as a consequence of the loop quantization procedure. It is found that, in addition to the initial modifications of the Hamiltonian, quantum corrections of the classical metric itself are needed as well in order to obtain generally covariant models. A comparison with recent alternative criteria is included in the discussion.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"67 1","pages":"105002"},"PeriodicalIF":3.5,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143920800","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":"Kiselev black strings: the charged rotating solutions","authors":"L G Barbosa, V H M Ramos, L C N Santos and C C Barros Jr","doi":"10.1088/1361-6382/add078","DOIUrl":"https://doi.org/10.1088/1361-6382/add078","url":null,"abstract":"We investigate the properties of a charged rotating black string immersed in a Kiselev anisotropic fluid in anti-de Sitter (AdS) spacetime. The Einstein–Maxwell equations with an anisotropic stress–energy tensor and cosmological constant are analyzed and solved exactly. In this work, we calculate the Kretschmann scalar, obtaining a consistent result that agrees with the existing literature in the absence of charge and fluid. The rotating solution is obtained by applying a coordinate transformation on time and angular coordinates. The event horizon associated with specific values of the equation of state parameter wq is studied. The results show an important influence of the fluid parameters Nq and wq , the charge parameter Q , and the rotation parameter a on the size of the black string horizon. In addition, we determine the conditions for the existence of closed timelike curves and compute the conserved charges, such as mass, angular momentum, and electric charge of the black string. Utilizing the Klein–Gordon equation, we employ the quantum particle tunneling approach to obtain the probability of charged scalar particles tunneling across the event horizon. We obtain the correspondent Hawking temperature as a consequence. Furthermore, we examine the thermodynamic properties, including entropy and heat capacity, to assess the effects of the quintessence field and charge on the black string. The results include particular cases such as the Lemos black string, providing a broader view of black string configurations in AdS spacetime.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"58 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143910040","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":"The third structure function","authors":"S P Miao, N C Tsamis, R P Woodard and B Yesilyurt","doi":"10.1088/1361-6382/adcfe9","DOIUrl":"https://doi.org/10.1088/1361-6382/adcfe9","url":null,"abstract":"We re-consider the graviton self-energy induced by a loop of massless, minimally coupled scalars on de Sitter background. On flat space background it can be represented as a sum of two tensor differential operators acting on scalar structure functions. On a general background these differential operators can be constructed from the linearized Ricci scalar and the linearized Weyl tensor. However, in cosmology one requires a third contribution which we derive here.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143910039","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":"Calculation method for eddy current effect of test mass in TianQin","authors":"Jia-Qi Wu, Xue-Yuan Li, Dan Peng, Hong-Mei Su and Qi Liu","doi":"10.1088/1361-6382/adcfea","DOIUrl":"https://doi.org/10.1088/1361-6382/adcfea","url":null,"abstract":"TianQin is proposed to detect gravitational wave signals at the frequency band of in space. Given that the residual acceleration noise of the test mass in TianQin is required to be below , all disturbing forces acting on the test mass should be estimated with the required precision. The magnetic force caused by eddy current is one of the error sources and should be treated seriously. In this paper, the eddy current effect is estimated by calculating the coupling between AC susceptibility and the applied ambient magnetic field. The proposed method demonstrates excellent agreement with direct calculations. The benefit of using the concept of AC susceptibility is that could be measured by precise experiment or calculated by FEM before launch, which improves the efficiency of calculation and increased the reliability and stability in space missions like TianQin.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"43 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143910041","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":"ROXAS: a new pseudospectral non-linear code for general relativistic oscillations of fast rotating isolated neutron stars","authors":"Gaël Servignat, Jérôme Novak","doi":"10.1088/1361-6382/adcd1e","DOIUrl":"https://doi.org/10.1088/1361-6382/adcd1e","url":null,"abstract":"Next-generation gravitational wave detectors are expected to increase their sensitivity in the kHz band where binary neutron star (NS) remnants are expected to emit. In this context, robust predictions of oscillation modes of the post-merger object are desirable. To that end, we present here our code <bold>R</bold>elativistic <bold>O</bold>scillations of non-a<bold>X</bold>isymmetric neutron st<bold>A</bold>r<bold>S</bold> (<monospace>ROXAS</monospace>) that is aimed at simulating isolated rotating NSs. It is based on our previously published formalism relying on primitive variables, along with the extended conformal-flatness condition formulation of Einstein equations. The equations are written under a well-balanced formulation. The code uses pseudospectral methods for both the metric and the hydrodynamics. Since standard test beds were already presented in a previous paper, we here mainly focus on presenting the numerical ingredients of <monospace>ROXAS</monospace>, as well as on the frequency extraction for axisymmetric and non-axisymmetric modes. We compare our results with semi-analytic perturbative methods. Spherically symmetric modes are also recovered. The code currently supports fast, rigidly rotating isolated NSs, described with a cold equation of state. We impose symmetries about the equatorial plane and by rotation of <italic toggle=\"yes\">π</italic> around the vertical <italic toggle=\"yes\">z</italic> axis. These symmetries include the dominant quadrupolar <inline-formula>\u0000<tex-math><?CDATA $ell = |m| = 2$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>ℓ</mml:mi><mml:mo>=</mml:mo><mml:mrow><mml:mo stretchy=\"false\">|</mml:mo></mml:mrow><mml:mi>m</mml:mi><mml:mrow><mml:mo stretchy=\"false\">|</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"cqgadcd1eieqn1.gif\"></inline-graphic></inline-formula> mode. A notable feature of the code is its ability to follow the surface of the star at every step. It is very lightweight and can be run on office computers.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"18 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143898280","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":"General shells and generalized functions","authors":"Albert Huber","doi":"10.1088/1361-6382/adcf6e","DOIUrl":"https://doi.org/10.1088/1361-6382/adcf6e","url":null,"abstract":"In this work, standard methods of the mixed thin-shell formalism are refined using the framework of Colombeau’s theory of generalized functions. To this end, systematic use is made of smooth generalized functions, in particular regularizations of the Heaviside step function and the delta distribution, instead of working directly with the corresponding Schwartz distributions. Based on this change of method, the resulting extended thin shell formalism is shown to offer a decisive advantage over traditional approaches to the subject: it avoids dealing with ill-defined products of distributions in the calculation of nonlinear curvature expressions, thereby allowing for the treatment of problems that prove intractable with the ‘conventional’ thin-shell formalism. This includes, in particular, the problem of matching singular spacetimes with distributional metrics (containing a delta distribution term) across a joint boundary hypersurface in spacetime, the problem of setting up the dominant energy condition for thin shells, and the problem of defining reasonably rigorously nonlinear distribution-valued curvature invariants needed in higher-derivative theories of gravity. Eventually, as a further application, close links to Penrose’s cut-and-paste method are established by proving that results of said method can be re-derived using the generalized formalism presented.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"14 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143898281","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":"On the dynamics of single-vertex states in quantum-reduced loop gravity","authors":"Ilkka Mäkinen","doi":"10.1088/1361-6382/adcdb9","DOIUrl":"https://doi.org/10.1088/1361-6382/adcdb9","url":null,"abstract":"In this article we examine a Hamiltonian constraint operator governing the dynamics of simple quantum states, whose graph consists of a single six-valent vertex, in quantum-reduced loop gravity. To this end, we first derive the action of the Hamiltonian constraint on generic basis states in the Hilbert space of quantum-reduced loop gravity. Specializing to the example of the single-vertex states, we find that the Euclidean part of the Hamiltonian bears a close formal similarity to the Hamiltonian constraint of Bianchi I models in loop quantum cosmology. Extending the formal analogy to the Lorentzian part of the Hamiltonian suggests a possible modified definition of the Hamiltonian constraint for loop quantum cosmology, in which the Lorentzian part, corresponding to the scalar curvature of the spatial surfaces, is not assumed to be identically vanishing, and is represented by a non-trivial operator in the quantum theory.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"10 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143889691","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":"Insights into binary neutron star merger simulations: a multi-code comparison","authors":"Maria C Babiuc Hamilton and William A Messman","doi":"10.1088/1361-6382/adccb1","DOIUrl":"https://doi.org/10.1088/1361-6382/adccb1","url":null,"abstract":"Gravitational Wave (GW) signals from binary neutron star (BNS) mergers provide critical insights into the properties of matter under extreme conditions. Due to the scarcity of observational data, numerical relativity (NR) simulations are indispensable for exploring these phenomena, without replacing the need for observational confirmation. However, simulating BNS mergers is a formidable challenge, and ensuring the consistency, reliability or convergence, especially in the post-merger, remains a work in progress. In this paper we assess the performance of current BNS merger simulations by analyzing open-source GW waveforms from five leading NR codes – SACRA, BAM, THC, Whisky, and SpEC. We focus on the accuracy of these simulations and on the effect of the equation of state on waveform predictions. We first check if different codes give similar results for similar initial data, then apply two methods to calculate convergence and quantify discretization errors. Lastly, we perform a thorough investigation into the effect of tidal interactions on key frequencies in the GW spectrum. We introduce a novel quasi-universal relation for the transient post-merger time, enhancing our understanding of remnant dynamics in this region. This detailed analysis clarifies agreements and discrepancies between these leading NR codes, and highlights necessary improvements for the advanced accuracy requirements of future GW detectors.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"25 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143884629","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":"The merger of a black hole with a cosmological horizon","authors":"Maxime Gadioux and Hangzhi Wang","doi":"10.1088/1361-6382/adce51","DOIUrl":"https://doi.org/10.1088/1361-6382/adce51","url":null,"abstract":"In recent years there have been many studies on exactly solvable black hole mergers, based on a model by Emparan and Martínez where the mass of one black hole is blown up to infinity (Emparan and Martínez 2016 Class. Quantum Grav.33 155003). Here we replace the large black hole by a cosmological horizon, and study how it merges with a black hole in the Schwarzschild-de Sitter spacetime by considering an observer positioned at future null infinity. We describe the geometry of the horizon over time, including the role that caustics play in the merger process, and also examine the growth of the horizon area. We argue that in the limit of zero cosmological constant, the system reduces to the Emparan-Martínez Schwarzschild merger. This allows us to regularize the increase in the area during the merger, which otherwise diverges.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"40 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143880431","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}