Pub Date : 2024-11-19DOI: 10.1088/1361-6382/ad8f26
Charlie Hoy, Connor R Weaving, Laura K Nuttall and Ian Harry
The laser interferometer space antenna (LISA) will observe gravitational-wave (GW) signals from a wide range of sources, including massive black hole binaries (MBHBs). Although numerous techniques have been developed to perform Bayesian inference for LISA, they are often computationally expensive; analyses often take at least ∼1 month on a single CPU, even when using accelerated techniques. Not only does this make it difficult to concurrently analyse more than one GW signal, it also makes it challenging to rapidly produce parameter estimates for possible electromagnetic follow-up campaigns. simple-pe was recently developed to produce rapid parameter estimates for GW signals observed with ground-based GW detectors. In this work, we extend simple-pe to produce rapid parameter estimates for LISA sources, including the effects of higher order multipole moments. We show that simple-pe infers the source properties of massive black hole binaries in zero-noise at least faster than existing techniques; h on a single CPU. We further demonstrate that simple-pe can be applied before existing Bayesian techniques to mitigate biases in multi-modal parameter estimation analyses of MBHBs.
激光干涉仪空间天线（LISA）将观测来自各种信号源的引力波（GW）信号，包括大质量黑洞双星（MBHBs）。虽然为 LISA 开发了许多贝叶斯推理技术，但这些技术的计算成本往往很高；即使使用加速技术，单个 CPU 的分析时间也至少需要 1 个月～1 个月。这不仅使同时分析一个以上的 GW 信号变得困难，也使为可能的电磁跟踪活动快速生成参数估计变得具有挑战性。最近开发了 simple-pe，用于为地面 GW 探测器观测到的 GW 信号快速生成参数估计。在这项工作中，我们对 simple-pe 进行了扩展，以快速估算 LISA 信号源的参数，包括高阶多极矩的影响。我们的研究表明，simple-pe 在零噪声条件下推断大质量黑洞双星的源属性至少比现有技术更快；而且只需一个 CPU。我们进一步证明，simple-pe 可以在现有贝叶斯技术之前应用，以减轻 MBHB 多模式参数估计分析中的偏差。
{"title":"A rapid multi-modal parameter estimation technique for LISA","authors":"Charlie Hoy, Connor R Weaving, Laura K Nuttall and Ian Harry","doi":"10.1088/1361-6382/ad8f26","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8f26","url":null,"abstract":"The laser interferometer space antenna (LISA) will observe gravitational-wave (GW) signals from a wide range of sources, including massive black hole binaries (MBHBs). Although numerous techniques have been developed to perform Bayesian inference for LISA, they are often computationally expensive; analyses often take at least ∼1 month on a single CPU, even when using accelerated techniques. Not only does this make it difficult to concurrently analyse more than one GW signal, it also makes it challenging to rapidly produce parameter estimates for possible electromagnetic follow-up campaigns. simple-pe was recently developed to produce rapid parameter estimates for GW signals observed with ground-based GW detectors. In this work, we extend simple-pe to produce rapid parameter estimates for LISA sources, including the effects of higher order multipole moments. We show that simple-pe infers the source properties of massive black hole binaries in zero-noise at least faster than existing techniques; h on a single CPU. We further demonstrate that simple-pe can be applied before existing Bayesian techniques to mitigate biases in multi-modal parameter estimation analyses of MBHBs.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"173 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670907","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 : 2024-11-18DOI: 10.1088/1361-6382/ad8d2e
Souvik Jana, Shasvath J Kapadia, Tejaswi Venumadhav, Surhud More and Parameswaran Ajith
We present a detailed exposition of a statistical method for estimating cosmological parameters from the observation of a large number of strongly lensed binary-black-hole (BBH) mergers observable by next (third) generation (XG) gravitational-wave (GW) detectors. This method, first presented in Jana (2023 Phys. Rev. Lett.130 261401), compares the observed number of strongly lensed GW events and their time delay distribution (between lensed images) with observed events to infer cosmological parameters. We show that the precision of the estimation of the cosmological parameters does not have a strong dependance on the assumed BBH redshift distribution model. Using the large number of unlensed mergers, XG detectors are expected to measure the BBH redshift distribution with sufficient precision for the cosmological inference. However, a biased inference of the BBH redshift distribution will bias the estimation of cosmological parameters. An incorrect model for the distribution of lens properties can also lead to a biased cosmological inference. However, Bayesian model selection can assist in selecting the right model from a set of available parametric models for the lens distribution. We also present a way to incorporate the effect of contamination in the data due to the limited efficiency of lensing identification methods, so that it will not bias the cosmological inference.
{"title":"Strong-lensing cosmography using third-generation gravitational-wave detectors","authors":"Souvik Jana, Shasvath J Kapadia, Tejaswi Venumadhav, Surhud More and Parameswaran Ajith","doi":"10.1088/1361-6382/ad8d2e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8d2e","url":null,"abstract":"We present a detailed exposition of a statistical method for estimating cosmological parameters from the observation of a large number of strongly lensed binary-black-hole (BBH) mergers observable by next (third) generation (XG) gravitational-wave (GW) detectors. This method, first presented in Jana (2023 Phys. Rev. Lett.130 261401), compares the observed number of strongly lensed GW events and their time delay distribution (between lensed images) with observed events to infer cosmological parameters. We show that the precision of the estimation of the cosmological parameters does not have a strong dependance on the assumed BBH redshift distribution model. Using the large number of unlensed mergers, XG detectors are expected to measure the BBH redshift distribution with sufficient precision for the cosmological inference. However, a biased inference of the BBH redshift distribution will bias the estimation of cosmological parameters. An incorrect model for the distribution of lens properties can also lead to a biased cosmological inference. However, Bayesian model selection can assist in selecting the right model from a set of available parametric models for the lens distribution. We also present a way to incorporate the effect of contamination in the data due to the limited efficiency of lensing identification methods, so that it will not bias the cosmological inference.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"66 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670343","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 : 2024-11-18DOI: 10.1088/1361-6382/ad8f8d
Ulf Danielsson and Vincent Van Hemelryck
In this paper, we realise the charged Nariai black hole on a braneworld from a nucleated bubble in AdS5, known as the dark bubble model. Geometrically, the black hole takes the form of a cylindrical spacetime pulling on the dark bubble. This is realised by a brane embedding in an AdS5 black string background. Identifying the brane with a D3-brane in string theory allows us to determine a relation between the fine structure constant and the string coupling, , which was previously obtained for a microscopic black hole. We also speculate on the consequences for the Festina Lente bound and neutrino masses.
{"title":"Charged Nariai black holes on the dark bubble","authors":"Ulf Danielsson and Vincent Van Hemelryck","doi":"10.1088/1361-6382/ad8f8d","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8f8d","url":null,"abstract":"In this paper, we realise the charged Nariai black hole on a braneworld from a nucleated bubble in AdS5, known as the dark bubble model. Geometrically, the black hole takes the form of a cylindrical spacetime pulling on the dark bubble. This is realised by a brane embedding in an AdS5 black string background. Identifying the brane with a D3-brane in string theory allows us to determine a relation between the fine structure constant and the string coupling, , which was previously obtained for a microscopic black hole. We also speculate on the consequences for the Festina Lente bound and neutrino masses.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670316","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 : 2024-11-18DOI: 10.1088/1361-6382/ad84ae
Collin D Capano, Jahed Abedi, Shilpa Kastha, Alexander H Nitz, Julian Westerweck, Yi-Fan Wang, Miriam Cabero, Alex B Nielsen and Badri Krishnan
A major aim of gravitational wave astronomy is to test observationally the Kerr nature of black holes. The strongest such test, with minimal additional assumptions, is provided by observations of multiple ringdown modes, also known as black hole spectroscopy. For the gravitational wave merger event GW190521, we have previously claimed the detection of two ringdown modes emitted by the remnant black hole. In this paper we provide further evidence for the detection of multiple ringdown modes from this event. We analyse the recovery of simulated gravitational wave signals designed to replicate the ringdown properties of GW190521. We quantify how often our detection statistic reports strong evidence for a sub-dominant ringdown mode, even when no such mode is present in the simulated signal. We find this only occurs with a probability ∼0.02, which is consistent with a Bayes factor of (1σ uncertainty) found for GW190521. We also quantify our agnostic analysis of GW190521, in which no relationship is assumed between ringdown modes, and find that only 1 in 250 simulated signals without a mode yields a result as significant as GW190521. Conversely, we verify that when simulated signals do have an observable mode they consistently yield a strong evidence and significant agnostic results. We also find that constraints on deviations from the mode on GW190521-like signals with a mode are consistent with what was obtained from our previous analysis of GW190521. Our results support our previous conclusion that the gravitational wave signal from GW190521 contains an observable sub-dominant mode.
{"title":"Estimating false alarm rates of sub-dominant quasi-normal modes in GW190521","authors":"Collin D Capano, Jahed Abedi, Shilpa Kastha, Alexander H Nitz, Julian Westerweck, Yi-Fan Wang, Miriam Cabero, Alex B Nielsen and Badri Krishnan","doi":"10.1088/1361-6382/ad84ae","DOIUrl":"https://doi.org/10.1088/1361-6382/ad84ae","url":null,"abstract":"A major aim of gravitational wave astronomy is to test observationally the Kerr nature of black holes. The strongest such test, with minimal additional assumptions, is provided by observations of multiple ringdown modes, also known as black hole spectroscopy. For the gravitational wave merger event GW190521, we have previously claimed the detection of two ringdown modes emitted by the remnant black hole. In this paper we provide further evidence for the detection of multiple ringdown modes from this event. We analyse the recovery of simulated gravitational wave signals designed to replicate the ringdown properties of GW190521. We quantify how often our detection statistic reports strong evidence for a sub-dominant ringdown mode, even when no such mode is present in the simulated signal. We find this only occurs with a probability ∼0.02, which is consistent with a Bayes factor of (1σ uncertainty) found for GW190521. We also quantify our agnostic analysis of GW190521, in which no relationship is assumed between ringdown modes, and find that only 1 in 250 simulated signals without a mode yields a result as significant as GW190521. Conversely, we verify that when simulated signals do have an observable mode they consistently yield a strong evidence and significant agnostic results. We also find that constraints on deviations from the mode on GW190521-like signals with a mode are consistent with what was obtained from our previous analysis of GW190521. Our results support our previous conclusion that the gravitational wave signal from GW190521 contains an observable sub-dominant mode.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"33 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670342","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 : 2024-11-15DOI: 10.1088/1361-6382/ad8e28
Zhang-Qi Wu, Pan-Pan Wang, Jun Ke and Cheng-Gang Shao
Arm-locking technique has been a focus of attention as one of the means to suppress the laser phase noise in space-based gravitational wave detector. The main idea of the arm-locking technique is to transfer the stability of the detector arm length to laser frequency by introducing a feedback control loop. Generally, laser phase noise will be suppressed by an amount similar to the magnitude of the controller gain. However, on the one hand, clock-jitter noise and optical bench motion noise, as the noise floor of the arm-locking technique, need to be suppressed. On the other hand, limited by the Doppler frequency pulling, the gain of the controller generally cannot be too large. It means that even if we do not consider clock-jitter noise and optical bench motion noise, it is difficult to suppress laser phase noise below the noise floor only by arm-locking technique. In this work, we combine self-referenced optical frequency combs and arm-locking technique to generate clock signals that are coherently referenced to the closed-loop laser beams, so that the clock-jitter noise is also suppressed by about the level of controller gain. We conduct a simulation on the above configuration, and the results show that the performance of the arm-locking is no longer limited by clock-jitter noise in the low-frequency band. To address the issue of insufficient laser phase noise suppression by the arm-locking technique, we further investigate time-delay interferometry (TDI) combinations under outputs of arbitrary arm-locking configurations. We obtain the equations for eliminating laser phase noise. To ensure that the TDI combinations can directly operate in the time domain, we derive a restricted solution space by assuming a specific form for the solutions.
{"title":"Suppression of clock-jitter noise and laser phase noise in arm locking","authors":"Zhang-Qi Wu, Pan-Pan Wang, Jun Ke and Cheng-Gang Shao","doi":"10.1088/1361-6382/ad8e28","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8e28","url":null,"abstract":"Arm-locking technique has been a focus of attention as one of the means to suppress the laser phase noise in space-based gravitational wave detector. The main idea of the arm-locking technique is to transfer the stability of the detector arm length to laser frequency by introducing a feedback control loop. Generally, laser phase noise will be suppressed by an amount similar to the magnitude of the controller gain. However, on the one hand, clock-jitter noise and optical bench motion noise, as the noise floor of the arm-locking technique, need to be suppressed. On the other hand, limited by the Doppler frequency pulling, the gain of the controller generally cannot be too large. It means that even if we do not consider clock-jitter noise and optical bench motion noise, it is difficult to suppress laser phase noise below the noise floor only by arm-locking technique. In this work, we combine self-referenced optical frequency combs and arm-locking technique to generate clock signals that are coherently referenced to the closed-loop laser beams, so that the clock-jitter noise is also suppressed by about the level of controller gain. We conduct a simulation on the above configuration, and the results show that the performance of the arm-locking is no longer limited by clock-jitter noise in the low-frequency band. To address the issue of insufficient laser phase noise suppression by the arm-locking technique, we further investigate time-delay interferometry (TDI) combinations under outputs of arbitrary arm-locking configurations. We obtain the equations for eliminating laser phase noise. To ensure that the TDI combinations can directly operate in the time domain, we derive a restricted solution space by assuming a specific form for the solutions.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"160 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637198","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 : 2024-11-15DOI: 10.1088/1361-6382/ad8f8b
Julian Gurs, Nina Bode, Christian Darsow-Fromm, Henning Vahlbruch, Pascal Gewecke, Sebastian Steinlechner, Benno Willke and Roman Schnabel
All current gravitational wave (GW) observatories operate with Nd:YAG lasers with a wavelength of 1064 nm. The sensitivity of future GW observatories could benefit significantly from changing the laser wavelength to approximately 2 µm combined with exchanging the current room temperature test mass mirrors with cryogenically cooled crystalline silicon test masses with mirror coatings from amorphous silicon and amorphous silicon nitride layers. Laser light of the order of ten watts with a low relative power noise (RPN) would be required. Here we use a laboratory-built degenerate optical parametric oscillator to convert the light from a high-power Nd:YAG laser to 2128 nm. With an input power of 30 W, we achieve an output power of 20 W, which corresponds to an external conversion efficiency of approximately 67%. We find that the RPN spectrum marginally increases during the wavelength conversion process. Our result is an important step in the development of low-noise light around 2 µm based on existing low-noise Nd:YAG lasers.
{"title":"Conversion of 30 W laser light at 1064 nm to 20 W at 2128 nm and comparison of relative power noise","authors":"Julian Gurs, Nina Bode, Christian Darsow-Fromm, Henning Vahlbruch, Pascal Gewecke, Sebastian Steinlechner, Benno Willke and Roman Schnabel","doi":"10.1088/1361-6382/ad8f8b","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8f8b","url":null,"abstract":"All current gravitational wave (GW) observatories operate with Nd:YAG lasers with a wavelength of 1064 nm. The sensitivity of future GW observatories could benefit significantly from changing the laser wavelength to approximately 2 µm combined with exchanging the current room temperature test mass mirrors with cryogenically cooled crystalline silicon test masses with mirror coatings from amorphous silicon and amorphous silicon nitride layers. Laser light of the order of ten watts with a low relative power noise (RPN) would be required. Here we use a laboratory-built degenerate optical parametric oscillator to convert the light from a high-power Nd:YAG laser to 2128 nm. With an input power of 30 W, we achieve an output power of 20 W, which corresponds to an external conversion efficiency of approximately 67%. We find that the RPN spectrum marginally increases during the wavelength conversion process. Our result is an important step in the development of low-noise light around 2 µm based on existing low-noise Nd:YAG lasers.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"46 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637203","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 : 2024-11-13DOI: 10.1088/1361-6382/ad8d9d
Tayyab Naseer and M Sharif
We develop multiple analytical solutions to the Rastall field equations using a recently proposed scheme, named the gravitational decoupling. In order to do this, we assume a spherical distribution that possesses anisotropic pressure in its interior and extend it by incorporating an additional gravitating source through the corresponding Lagrangian density. Such addition in the initial fluid distribution leads to the complicated field equations which are then tackled by implementing the minimal geometric deformation. This execution divides these equations into two different systems, each corresponds to the original source. The first system representing initial source is solved by adopting Krori–Barua and Tolman IV spacetimes, while three different constraints are used to work out the other set. The constants engaged in the above two ansatz are calculated through the junction conditions. The developed models are further explored graphically in the interior of a star, say . Finally, we conclude our results to be physically feasible under the considered variation in both Rastall and decoupling parameters. It is important to mention here that the derived models can be viewed as idealized or toy models that serve as preliminary explorations within the framework of Rastall gravity.
我们利用最近提出的一种名为引力解耦的方案，开发了拉斯塔尔场方程的多种解析解。为此，我们假定球形分布在其内部具有各向异性的压力，并通过相应的拉格朗日密度加入额外的引力源对其进行扩展。初始流体分布中的这种添加会导致复杂的场方程，然后通过最小几何变形来处理这些方程。这种执行方式将这些方程分为两个不同的系统，每个系统都与原始源相对应。代表初始源的第一个系统通过采用 Krori-Barua 和 Tolman IV 空间时间来求解，而另一组则采用三种不同的约束条件来求解。上述两个等式中的常数是通过交界条件计算得出的。我们将在恒星内部（例如......）对所建立的模型进行进一步的图形探索。最后，我们得出结论，在所考虑的拉斯托尔参数和去耦参数变化下，我们的结果在物理上是可行的。在此有必要提及的是，推导出的模型可视为理想化或玩具模型，可作为拉斯塔尔引力框架内的初步探索。
{"title":"Role of decoupling and Rastall parameters on Krori–Barua and Tolman IV models generated by isotropization and complexity factor","authors":"Tayyab Naseer and M Sharif","doi":"10.1088/1361-6382/ad8d9d","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8d9d","url":null,"abstract":"We develop multiple analytical solutions to the Rastall field equations using a recently proposed scheme, named the gravitational decoupling. In order to do this, we assume a spherical distribution that possesses anisotropic pressure in its interior and extend it by incorporating an additional gravitating source through the corresponding Lagrangian density. Such addition in the initial fluid distribution leads to the complicated field equations which are then tackled by implementing the minimal geometric deformation. This execution divides these equations into two different systems, each corresponds to the original source. The first system representing initial source is solved by adopting Krori–Barua and Tolman IV spacetimes, while three different constraints are used to work out the other set. The constants engaged in the above two ansatz are calculated through the junction conditions. The developed models are further explored graphically in the interior of a star, say . Finally, we conclude our results to be physically feasible under the considered variation in both Rastall and decoupling parameters. It is important to mention here that the derived models can be viewed as idealized or toy models that serve as preliminary explorations within the framework of Rastall gravity.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601263","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 : 2024-11-13DOI: 10.1088/1361-6382/ad8d9e
Luca Fabbri
We consider the problem of having relativistic quantum mechanics re-formulated with hydrodynamic variables, and specifically the problem of deriving the Mathisson–Papapetrou–Dixon equations (describing the motion of a massive spinning body moving in a gravitational field) from the Dirac equation. The problem will be answered on a general manifold with torsion and gravity. We will demonstrate that when plane waves are considered the MPD equations describe the general relativistic wave-particle duality with torsion (Guedes and Popławski 2024 Class. Quantum Grav.41 065011), but we will also see that in such a form the MPD equations become trivial.
我们考虑用流体力学变量重新表述相对论量子力学的问题，特别是从狄拉克方程导出马蒂森-帕佩特罗-狄克逊方程（描述在引力场中运动的大质量旋转体的运动）的问题。这个问题将在具有扭转和引力的一般流形上得到解答。我们将证明，当考虑平面波时，MPD方程描述了具有扭转的广义相对论波粒二象性（Guedes and Popławski 2024 Class. Quantum Grav.41 065011），但我们也将看到，在这种形式下，MPD方程变得微不足道。
{"title":"Classical characters of spinor fields in torsion gravity","authors":"Luca Fabbri","doi":"10.1088/1361-6382/ad8d9e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8d9e","url":null,"abstract":"We consider the problem of having relativistic quantum mechanics re-formulated with hydrodynamic variables, and specifically the problem of deriving the Mathisson–Papapetrou–Dixon equations (describing the motion of a massive spinning body moving in a gravitational field) from the Dirac equation. The problem will be answered on a general manifold with torsion and gravity. We will demonstrate that when plane waves are considered the MPD equations describe the general relativistic wave-particle duality with torsion (Guedes and Popławski 2024 Class. Quantum Grav.41 065011), but we will also see that in such a form the MPD equations become trivial.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"156 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601264","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 : 2024-11-12DOI: 10.1088/1361-6382/ad8c1e
Fabio M Mele and Johannes Münch
In spatially non-compact homogeneous minisuperpace models, spatial integrals in the Hamiltonian and symplectic form must be regularised by confining them to a finite volume Vo, known as the fiducial cell. As this restriction is unnecessary in the complete field theory before homogeneous reduction, the physical significance of the fiducial cell has been largely debated, especially in the context of (loop) quantum cosmology. Understanding the role of Vo is in turn essential for assessing the minisuperspace description’s validity and its connection to the full theory. In this work we present a systematic procedure for the field theory reduction to spatially homogeneous and isotropic minisuperspaces within the canonical framework and apply it to both a massive scalar field theory and gravity. Our strategy consists in implementing spatial homogeneity via second-class constraints for the discrete field modes over a partitioning of the spatial slice into countably many disjoint cells. The reduced theory’s canonical structure is then given by the corresponding Dirac bracket. Importantly, the latter can only be defined on a finite number of cells homogeneously patched together. This identifies a finite region, the fiducial cell, whose physical size acquires then a precise meaning already at the classical level as the scale over which homogeneity is imposed. Additionally, the procedure allows us to track the information lost during homogeneous reduction and how the error depends on Vo. We then move to the quantisation of the classically reduced theories, focusing in particular on the relation between the theories for different Vo, and study the implications for statistical moments, quantum fluctuations, and semiclassical states. In the case of a quantum scalar field, a subsector of the full quantum field theory where the results from the ‘first reduced, then quantised’ approach can be reproduced is identified and the conditions for this to be a good approximation are also determined.
{"title":"On the role of fiducial structures in minisuperspace reduction and quantum fluctuations in LQC","authors":"Fabio M Mele and Johannes Münch","doi":"10.1088/1361-6382/ad8c1e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8c1e","url":null,"abstract":"In spatially non-compact homogeneous minisuperpace models, spatial integrals in the Hamiltonian and symplectic form must be regularised by confining them to a finite volume Vo, known as the fiducial cell. As this restriction is unnecessary in the complete field theory before homogeneous reduction, the physical significance of the fiducial cell has been largely debated, especially in the context of (loop) quantum cosmology. Understanding the role of Vo is in turn essential for assessing the minisuperspace description’s validity and its connection to the full theory. In this work we present a systematic procedure for the field theory reduction to spatially homogeneous and isotropic minisuperspaces within the canonical framework and apply it to both a massive scalar field theory and gravity. Our strategy consists in implementing spatial homogeneity via second-class constraints for the discrete field modes over a partitioning of the spatial slice into countably many disjoint cells. The reduced theory’s canonical structure is then given by the corresponding Dirac bracket. Importantly, the latter can only be defined on a finite number of cells homogeneously patched together. This identifies a finite region, the fiducial cell, whose physical size acquires then a precise meaning already at the classical level as the scale over which homogeneity is imposed. Additionally, the procedure allows us to track the information lost during homogeneous reduction and how the error depends on Vo. We then move to the quantisation of the classically reduced theories, focusing in particular on the relation between the theories for different Vo, and study the implications for statistical moments, quantum fluctuations, and semiclassical states. In the case of a quantum scalar field, a subsector of the full quantum field theory where the results from the ‘first reduced, then quantised’ approach can be reproduced is identified and the conditions for this to be a good approximation are also determined.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"5 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599454","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 : 2024-11-12DOI: 10.1088/1361-6382/ad8b93
César A Zen Vasconcellos, Peter O Hess, José de Freitas Pacheco, Fridolin Weber, Benno Bodmann, Dimiter Hadjimichef, Geovane Naysinger, Marcelo Netz-Marzola and Moisés Razeira
Based on an analytically continued Riemannian foliated quantum gravity super-Hamiltonian, known as branch cut quantum gravity (BCQG) we propose a novel approach to investigating the effects of noncommutative geometry on a minisuperspace of variables, influencing the acceleration behavior of the Universe’s wave function and the cosmic scale factor. Noncommutativity is introduced through a deformation of the conventional Poisson algebra, enhanced with a symplectic metric. The resulting symplectic manifold provides a natural setting that enables an isomorphism between canonically conjugate dual vector spaces, spanning the BCQG cosmic scale factor and its complementary quantum counterpart. Using this formulation, we describe the dynamic evolution of the Universe’s wave function, the cosmic scale factor, and its complementary quantum image. Our results strongly suggest that the noncommutative algebra induces late-time accelerated growth of the wave function, the Universe’s scale factor, and its complementary quantum counterpart, offering a new perspective on explaining the accelerating cosmic expansion rate and the inflationary period. In contrast to the inflationary model, where inflation requires a remarkably fine-tuned set of initial conditions in a patch of the Universe, analytically continued non-commutative foliated quantum gravity captures short and long scales, driving the evolutionary dynamics of the Universe through a reconfiguration of the primordial cosmic content of matter and energy. This reconfiguration is encapsulated into a quantum field potential, which leads to the generation of relic gravitational waves, a topic for future investigation. Graphical representations and contour plots indicate a characteristic torsion (or twist) deformation of spacetime geometry. This result introduces new speculative elements regarding the reconfiguration of matter and energy as a driver of spacetime torsion deformation, generating relic gravitational waves and serving as an alternative topological mechanism for the Universe’s acceleration. However, these assumptions require further investigation.
{"title":"The accelerating universe in a noncommutative analytically continued foliated quantum gravity","authors":"César A Zen Vasconcellos, Peter O Hess, José de Freitas Pacheco, Fridolin Weber, Benno Bodmann, Dimiter Hadjimichef, Geovane Naysinger, Marcelo Netz-Marzola and Moisés Razeira","doi":"10.1088/1361-6382/ad8b93","DOIUrl":"https://doi.org/10.1088/1361-6382/ad8b93","url":null,"abstract":"Based on an analytically continued Riemannian foliated quantum gravity super-Hamiltonian, known as branch cut quantum gravity (BCQG) we propose a novel approach to investigating the effects of noncommutative geometry on a minisuperspace of variables, influencing the acceleration behavior of the Universe’s wave function and the cosmic scale factor. Noncommutativity is introduced through a deformation of the conventional Poisson algebra, enhanced with a symplectic metric. The resulting symplectic manifold provides a natural setting that enables an isomorphism between canonically conjugate dual vector spaces, spanning the BCQG cosmic scale factor and its complementary quantum counterpart. Using this formulation, we describe the dynamic evolution of the Universe’s wave function, the cosmic scale factor, and its complementary quantum image. Our results strongly suggest that the noncommutative algebra induces late-time accelerated growth of the wave function, the Universe’s scale factor, and its complementary quantum counterpart, offering a new perspective on explaining the accelerating cosmic expansion rate and the inflationary period. In contrast to the inflationary model, where inflation requires a remarkably fine-tuned set of initial conditions in a patch of the Universe, analytically continued non-commutative foliated quantum gravity captures short and long scales, driving the evolutionary dynamics of the Universe through a reconfiguration of the primordial cosmic content of matter and energy. This reconfiguration is encapsulated into a quantum field potential, which leads to the generation of relic gravitational waves, a topic for future investigation. Graphical representations and contour plots indicate a characteristic torsion (or twist) deformation of spacetime geometry. This result introduces new speculative elements regarding the reconfiguration of matter and energy as a driver of spacetime torsion deformation, generating relic gravitational waves and serving as an alternative topological mechanism for the Universe’s acceleration. However, these assumptions require further investigation.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"71 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599453","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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