Pub Date : 2026-02-10DOI: 10.1088/1361-6382/ae0aad
K E Saavik Ford and Barry McKernan
Active galactic nuclei (AGN) are powered by accretion disks onto supermassive black holes (SMBHs) in the centers of galaxies. AGN are believed to play important roles in the evolution of both SMBHs and their host galaxies over cosmic time. AGN and the nuclear star clusters (NSCs) that interact with them remain unresolved with present and planned telescopes. As a result, the properties of AGN and NSCs are highly uncertain. Here we review how binary black hole (BBH) mergers can occur in AGN disks and how both the gravitational wave and electromagnetic wave properties of such mergers allow us to reverse-engineer the properties of AGN disks and NSCs over cosmic time. We point out that the feature in the BBH mass spectrum around is an excellent probe of hierarchical merger models. Likewise constraints on the spins of upper-mass gap BH ( ) test the AGN channel. The effective spin ( ) distribution, including asymmetry, islands of structure and magnitudes are excellent tests of AGN model predictions. We also argue, that the rate of AGN-driven BBH mergers as a function of redshift should scale slightly shallower than the AGN number density, at least out to redshifts of , and should turnover at the same redshift as the AGN number density. Finally, we emphasize a determination of an AGN fraction of observed BBH mergers ( ), regardless of the actual value, allows us to infer the average properties of AGN disks and NSCs out to high redshift.
{"title":"Using gravitational waves & multi-messenger astronomy to reverse-engineer the properties of galactic nuclei","authors":"K E Saavik Ford and Barry McKernan","doi":"10.1088/1361-6382/ae0aad","DOIUrl":"https://doi.org/10.1088/1361-6382/ae0aad","url":null,"abstract":"Active galactic nuclei (AGN) are powered by accretion disks onto supermassive black holes (SMBHs) in the centers of galaxies. AGN are believed to play important roles in the evolution of both SMBHs and their host galaxies over cosmic time. AGN and the nuclear star clusters (NSCs) that interact with them remain unresolved with present and planned telescopes. As a result, the properties of AGN and NSCs are highly uncertain. Here we review how binary black hole (BBH) mergers can occur in AGN disks and how both the gravitational wave and electromagnetic wave properties of such mergers allow us to reverse-engineer the properties of AGN disks and NSCs over cosmic time. We point out that the feature in the BBH mass spectrum around is an excellent probe of hierarchical merger models. Likewise constraints on the spins of upper-mass gap BH ( ) test the AGN channel. The effective spin ( ) distribution, including asymmetry, islands of structure and magnitudes are excellent tests of AGN model predictions. We also argue, that the rate of AGN-driven BBH mergers as a function of redshift should scale slightly shallower than the AGN number density, at least out to redshifts of , and should turnover at the same redshift as the AGN number density. Finally, we emphasize a determination of an AGN fraction of observed BBH mergers ( ), regardless of the actual value, allows us to infer the average properties of AGN disks and NSCs out to high redshift.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"15 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146188","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 : 2026-02-10DOI: 10.1088/1361-6382/ae3b91
Anthony W Yu, Molly E Fahey, Kenji Numata, Yvonne Kandem Manewa, Ali Feizi, Frankie Micalizzi, Hua Jiao, Joseph Hart, Xiaozhen Xu, Stewart Wu, Kylan Jersey, Will Drobnick, Pat Burns, Jennifer Lee and Scott Merritt
NASA Goddard Space Flight Center (GSFC) is developing a laser system (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency with a launch date of 2035. The LS under development at NASA GSFC consists of a laser head, a frequency reference system, and power monitor detector assemblies. The LS development, which began in late 2016, follows the established NASA process in demonstrating the performance requirements through the development of various models to advance the technology readiness level (TRL) (www.nasa.gov/directorates/somd/space-communications-navigation-program/technology-readiness-levels/). The effort began with a successful demonstration of a laboratory breadboard (TRL 4) and has achieved a status of TRL-6 (flight-qualified) through rigorous testing and performance verification for space applications. In this paper, we provide an overview of the development and roadmap for advancing the LISA LS toward spaceflight by the NASA GSFC. Optomechanical and electronic details of each component and subsystems are presented in this paper, as well as test results and technical challenges that have been or are being overcome. As the project progresses, more detailed results will be reported in future publications including representative scientific data in support of the LISA launch, which is planned for 2035.
{"title":"Overview of the NASA LISA laser system development","authors":"Anthony W Yu, Molly E Fahey, Kenji Numata, Yvonne Kandem Manewa, Ali Feizi, Frankie Micalizzi, Hua Jiao, Joseph Hart, Xiaozhen Xu, Stewart Wu, Kylan Jersey, Will Drobnick, Pat Burns, Jennifer Lee and Scott Merritt","doi":"10.1088/1361-6382/ae3b91","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3b91","url":null,"abstract":"NASA Goddard Space Flight Center (GSFC) is developing a laser system (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency with a launch date of 2035. The LS under development at NASA GSFC consists of a laser head, a frequency reference system, and power monitor detector assemblies. The LS development, which began in late 2016, follows the established NASA process in demonstrating the performance requirements through the development of various models to advance the technology readiness level (TRL) (www.nasa.gov/directorates/somd/space-communications-navigation-program/technology-readiness-levels/). The effort began with a successful demonstration of a laboratory breadboard (TRL 4) and has achieved a status of TRL-6 (flight-qualified) through rigorous testing and performance verification for space applications. In this paper, we provide an overview of the development and roadmap for advancing the LISA LS toward spaceflight by the NASA GSFC. Optomechanical and electronic details of each component and subsystems are presented in this paper, as well as test results and technical challenges that have been or are being overcome. As the project progresses, more detailed results will be reported in future publications including representative scientific data in support of the LISA launch, which is planned for 2035.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"284 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146189","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 : 2026-02-09DOI: 10.1088/1361-6382/ae3e4b
Dipayan Mukherjee, Harkirat Singh Sahota and S Shankaranarayanan
Building upon our recently established correspondence between quantum cosmology and the hydrogen atom (Sahota et al 2025 arXiv:2505.16863 [gr-qc]), we investigate the specific sector of a negative cosmological constant ( ) in a flat FLRW Universe with dust. While the positive Λ sector (Sahota et al 2025 arXiv:2505.16863 [gr-qc]) yields a continuous spectrum and a single bounce, we show here that the negative Λ sector leads to a discrete spectrum of energy eigenvalues, effectively quantizing the cosmological constant. Within this dual description, the operator-ordering ambiguity parameter appears as the azimuthal quantum number of the hydrogen atom. A skewed Bohr correspondence emerges for the bound states, matching classical evolution at large volumes but deviating near the bounce. By constructing wave packets from these bound states, we demonstrate that the classical Big Bang and Big Crunch singularities are resolved, and the Universe oscillates between quantum bounces and classical turnaround points. The expectation values of the observables indicate a cyclic Universe—with vanishing Hubble parameter at turnarounds—undergoing quantum bounces. This exactly solvable model offers a tractable setting to explore quantum gravitational effects in cosmology. We analyze the properties of this cyclic Universe, contrasting its bound-state dynamics with the scattering states of the de Sitter case.
基于我们最近建立的量子宇宙学和氢原子之间的对应关系（Sahota et al 2025 arXiv:2505.16863 [gr-qc]），我们研究了一个平坦的FLRW宇宙中负宇宙常数（）的特定部分。当正的Λ扇区（Sahota et al 2025 arXiv:2505.16863 [gr-qc]）产生连续光谱和单一反弹时，我们在这里表明负的Λ扇区导致能量特征值的离散谱，有效地量化了宇宙常数。在这种对偶描述中，算子序模糊参数表现为氢原子的方位量子数。束缚态出现了扭曲的玻尔对应，在大体积下与经典演化相匹配，但在弹跳附近偏离。通过从这些束缚态构造波包，我们证明了经典的大爆炸和大压缩奇点是解决的，宇宙在量子弹跳和经典周转点之间振荡。可观测值的期望值表明，一个循环的宇宙正在经历量子反弹，而哈勃参数在转弯时消失。这个完全可解的模型为探索宇宙学中的量子引力效应提供了一个易于处理的环境。我们分析了这个循环宇宙的性质，对比了它的束缚态动力学和de Sitter情况下的散射态。
{"title":"Quantum cosmology as a hydrogen atom: discrete Λ and cyclic universes from Wheeler–DeWitt quantization","authors":"Dipayan Mukherjee, Harkirat Singh Sahota and S Shankaranarayanan","doi":"10.1088/1361-6382/ae3e4b","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3e4b","url":null,"abstract":"Building upon our recently established correspondence between quantum cosmology and the hydrogen atom (Sahota et al 2025 arXiv:2505.16863 [gr-qc]), we investigate the specific sector of a negative cosmological constant ( ) in a flat FLRW Universe with dust. While the positive Λ sector (Sahota et al 2025 arXiv:2505.16863 [gr-qc]) yields a continuous spectrum and a single bounce, we show here that the negative Λ sector leads to a discrete spectrum of energy eigenvalues, effectively quantizing the cosmological constant. Within this dual description, the operator-ordering ambiguity parameter appears as the azimuthal quantum number of the hydrogen atom. A skewed Bohr correspondence emerges for the bound states, matching classical evolution at large volumes but deviating near the bounce. By constructing wave packets from these bound states, we demonstrate that the classical Big Bang and Big Crunch singularities are resolved, and the Universe oscillates between quantum bounces and classical turnaround points. The expectation values of the observables indicate a cyclic Universe—with vanishing Hubble parameter at turnarounds—undergoing quantum bounces. This exactly solvable model offers a tractable setting to explore quantum gravitational effects in cosmology. We analyze the properties of this cyclic Universe, contrasting its bound-state dynamics with the scattering states of the de Sitter case.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"4 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138513","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 : 2026-02-06DOI: 10.1088/1361-6382/ae399b
Jinfeng Lu, Yizhou Zhang, Chujie Zhang, Ming Hu, Yanzheng Bai and Zebing Zhou
The space inertial sensor (IS) is a critical payload in space-based gravitational wave detection missions. The test mass, serving as the gravitational reference, should be maintained at the center of its electrode housing through AC electrostatic control and drag-free attitude control. However, excessive electrostatic actuation cross-coupling between degrees of freedom can significantly deteriorate the residual acceleration performance along the sensitive axis (x-axis). This paper investigates the influence of carrier frequency selection on the electrostatic actuation noise coupling from the ϕ-axis to the x-axis. The analysis shows that the coupling coefficient can be suppressed below over the 0.1 mHz–1 Hz band by properly choosing the AC carrier frequencies. Specifically, both the sum and the difference of the carrier frequencies should be integer multiples of the desired force/torque update rate . Furthermore, the difference frequency should exceed 180 Hz with a deviation smaller than 0.4% to satisfy TianQin’s requirement. These conclusions are validated through a dedicated Simulink simulation platform. The proposed frequency configuration guideline offers a clear basis for AC feedback design in IS, effectively suppressing cross-coupling and enhancing low-frequency performance for future space-based gravitational wave missions.
{"title":"AC actuation carrier frequency optimization for cross-coupling suppression in space inertial sensor","authors":"Jinfeng Lu, Yizhou Zhang, Chujie Zhang, Ming Hu, Yanzheng Bai and Zebing Zhou","doi":"10.1088/1361-6382/ae399b","DOIUrl":"https://doi.org/10.1088/1361-6382/ae399b","url":null,"abstract":"The space inertial sensor (IS) is a critical payload in space-based gravitational wave detection missions. The test mass, serving as the gravitational reference, should be maintained at the center of its electrode housing through AC electrostatic control and drag-free attitude control. However, excessive electrostatic actuation cross-coupling between degrees of freedom can significantly deteriorate the residual acceleration performance along the sensitive axis (x-axis). This paper investigates the influence of carrier frequency selection on the electrostatic actuation noise coupling from the ϕ-axis to the x-axis. The analysis shows that the coupling coefficient can be suppressed below over the 0.1 mHz–1 Hz band by properly choosing the AC carrier frequencies. Specifically, both the sum and the difference of the carrier frequencies should be integer multiples of the desired force/torque update rate . Furthermore, the difference frequency should exceed 180 Hz with a deviation smaller than 0.4% to satisfy TianQin’s requirement. These conclusions are validated through a dedicated Simulink simulation platform. The proposed frequency configuration guideline offers a clear basis for AC feedback design in IS, effectively suppressing cross-coupling and enhancing low-frequency performance for future space-based gravitational wave missions.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"48 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122221","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 : 2026-02-06DOI: 10.1088/1361-6382/ae3d27
Omar Chahboun, Rachid Ahl Laamara and El Hassan Saidi
This work presents a new approach to understanding dark matter and dark energy within the framework of 4-dimensional Einstein–Gauss–Bonnet gravity coupled to a scalar field. By treating dark matter as a curvature effect with negative mass properties arising from the Gauss–Bonnet term , we develop a model that unifies the dark sector through its interaction with the scalar field. Utilizing the symmetry , we examine the unified behavior of dark matter and dark energy before symmetry breaking and their decoupling afterward. We also explore the compatibility of our model with the Modified Newtonian Dynamics paradigm, where the coupling constant α encapsulates the imprints of dark matter. Furthermore, we constrain the model’s background parameters using 57 data points of H(z) and the reduced Pantheon dataset, which is statistically comparable to the Λ cold dark matter model. In the context of cosmological perturbations, we derive an effective gravitational constant, Geff, which depends on the coupling function and the Hubble parameter but aligns with the standard gravitational constant at the present time. Additionally, we establish a direct relationship between dark matter density perturbations, the curvature potential ψ, and the weak lensing potential , providing a geometric interpretation of dark matter effects. Another aspect of our study involves a thorough comparison between our model’s predictions and observational data for the linear cosmic structure growth function , along with the growth index γ, the matter power spectrum P and the halo mass function using Sheth–Tormen approximation. This unified framework offers new insights into the dark sector and its interplay with cosmic dynamics.
{"title":"Einstein–Gauss–Bonnet dark matter: negative masses, curvature effects and dark sector unification","authors":"Omar Chahboun, Rachid Ahl Laamara and El Hassan Saidi","doi":"10.1088/1361-6382/ae3d27","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3d27","url":null,"abstract":"This work presents a new approach to understanding dark matter and dark energy within the framework of 4-dimensional Einstein–Gauss–Bonnet gravity coupled to a scalar field. By treating dark matter as a curvature effect with negative mass properties arising from the Gauss–Bonnet term , we develop a model that unifies the dark sector through its interaction with the scalar field. Utilizing the symmetry , we examine the unified behavior of dark matter and dark energy before symmetry breaking and their decoupling afterward. We also explore the compatibility of our model with the Modified Newtonian Dynamics paradigm, where the coupling constant α encapsulates the imprints of dark matter. Furthermore, we constrain the model’s background parameters using 57 data points of H(z) and the reduced Pantheon dataset, which is statistically comparable to the Λ cold dark matter model. In the context of cosmological perturbations, we derive an effective gravitational constant, Geff, which depends on the coupling function and the Hubble parameter but aligns with the standard gravitational constant at the present time. Additionally, we establish a direct relationship between dark matter density perturbations, the curvature potential ψ, and the weak lensing potential , providing a geometric interpretation of dark matter effects. Another aspect of our study involves a thorough comparison between our model’s predictions and observational data for the linear cosmic structure growth function , along with the growth index γ, the matter power spectrum P and the halo mass function using Sheth–Tormen approximation. This unified framework offers new insights into the dark sector and its interplay with cosmic dynamics.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"15 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122224","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 : 2026-02-06DOI: 10.1088/1361-6382/ae3c52
Keita Takahashi
We extend Beem’s three completeness notions—finite compactness, timelike Cauchy completeness, and Condition A—originally defined for spacetimes, to Lorentzian length spaces and study their relationships. We prove that finite compactness implies timelike Cauchy completeness and that timelike Cauchy completeness implies Condition A for globally hyperbolic Lorentzian length spaces. Furthermore, for globally hyperbolic C1-spacetimes, we establish the equivalence of the three conditions assuming the causally non-branching and non-intertwining conditions, which in fact imply the continuity of the causal exponential map. These results can be regarded as a Hopf–Rinow type theorem for low-regularity Lorentzian geometry. The appendix presents examples of C1-spacetimes—where geodesic uniqueness may fail—in which causal geodesics nevertheless behave well, illustrating the scope of our results.
{"title":"Completeness conditions for spacetimes with low-regularity metrics","authors":"Keita Takahashi","doi":"10.1088/1361-6382/ae3c52","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3c52","url":null,"abstract":"We extend Beem’s three completeness notions—finite compactness, timelike Cauchy completeness, and Condition A—originally defined for spacetimes, to Lorentzian length spaces and study their relationships. We prove that finite compactness implies timelike Cauchy completeness and that timelike Cauchy completeness implies Condition A for globally hyperbolic Lorentzian length spaces. Furthermore, for globally hyperbolic C1-spacetimes, we establish the equivalence of the three conditions assuming the causally non-branching and non-intertwining conditions, which in fact imply the continuity of the causal exponential map. These results can be regarded as a Hopf–Rinow type theorem for low-regularity Lorentzian geometry. The appendix presents examples of C1-spacetimes—where geodesic uniqueness may fail—in which causal geodesics nevertheless behave well, illustrating the scope of our results.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122223","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 : 2026-02-06DOI: 10.1088/1361-6382/ae1b5f
Ashmita Roy, Suresh Doravari and Ravi Banavar
Ground-based interferometric gravitational wave detectors utilize suspended mirrors as ‘Test Masses’ to sense fluctuations in the fabric of space-time. These tandem, multi-stage suspensions are carefully designed such that the mirrors, which form a Michelson interferometer, behave as free masses undisturbed by extraneous forces such as seismic vibrations, within the bandwidth of the detectors (20 Hz–8 kHz).As a result of the achieved active and passive vibration isolation, the residual mirror motion could be as low as . This work explores robust control design techniques used in the active feedback mechanism of these suspensions, incorporating key concepts, such as loop shaping and normalized coprime factorization, to design a multi-input multi-output (MIMO) controller with optimization. We use a single-stage suspension as our test bed, as it provides a simpler plant than the multistage suspensions used in these interferometers, while also preserving the basic features of the MIMO suspension plant. A systematic methodology to design the frequency-dependent weighting functions tailored to these types suspension systems is developed, along with a figure of merit to optimize the performance of the controller. Further, an automated process is proposed to refine the design of our weighting functions for improved robust performance. The study also demonstrates that the resulting control design can also account for model uncertainties and nonlinearities specific to the suspension systems of Laser Interferometer Gravitational Wave Observatory.
{"title":"An optimized H ∞ ...","authors":"Ashmita Roy, Suresh Doravari and Ravi Banavar","doi":"10.1088/1361-6382/ae1b5f","DOIUrl":"https://doi.org/10.1088/1361-6382/ae1b5f","url":null,"abstract":"Ground-based interferometric gravitational wave detectors utilize suspended mirrors as ‘Test Masses’ to sense fluctuations in the fabric of space-time. These tandem, multi-stage suspensions are carefully designed such that the mirrors, which form a Michelson interferometer, behave as free masses undisturbed by extraneous forces such as seismic vibrations, within the bandwidth of the detectors (20 Hz–8 kHz).As a result of the achieved active and passive vibration isolation, the residual mirror motion could be as low as . This work explores robust control design techniques used in the active feedback mechanism of these suspensions, incorporating key concepts, such as loop shaping and normalized coprime factorization, to design a multi-input multi-output (MIMO) controller with optimization. We use a single-stage suspension as our test bed, as it provides a simpler plant than the multistage suspensions used in these interferometers, while also preserving the basic features of the MIMO suspension plant. A systematic methodology to design the frequency-dependent weighting functions tailored to these types suspension systems is developed, along with a figure of merit to optimize the performance of the controller. Further, an automated process is proposed to refine the design of our weighting functions for improved robust performance. The study also demonstrates that the resulting control design can also account for model uncertainties and nonlinearities specific to the suspension systems of Laser Interferometer Gravitational Wave Observatory.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"84 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122413","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 : 2026-02-06DOI: 10.1088/1361-6382/ae3b93
Vincent R Siggia, Eric D Carlson and P Lee Pryor
We consider Type Ia supernova data in the context of gravity. We consider functions of the form where ε < 1. We find that for all models with ε < 0, the Universe transitions to exponential growth at late times, just as it does in the standard cosmological model, which corresponds to ε = 0. It also fits the type Ia supernova data slightly better than the standard cosmological model, without increasing the number of parameters of the theory. In contrast, the fits for ε > 0 rapidly become worse than the standard cosmological model.
我们在重力的背景下考虑Ia型超新星的数据。我们考虑ε 0迅速变得比标准宇宙学模型差的形式的函数。
{"title":"Exploration of parameters in f(R,T) gravity and comparison with type Ia supernovae data","authors":"Vincent R Siggia, Eric D Carlson and P Lee Pryor","doi":"10.1088/1361-6382/ae3b93","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3b93","url":null,"abstract":"We consider Type Ia supernova data in the context of gravity. We consider functions of the form where ε < 1. We find that for all models with ε < 0, the Universe transitions to exponential growth at late times, just as it does in the standard cosmological model, which corresponds to ε = 0. It also fits the type Ia supernova data slightly better than the standard cosmological model, without increasing the number of parameters of the theory. In contrast, the fits for ε > 0 rapidly become worse than the standard cosmological model.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"56 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122222","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 : 2026-02-05DOI: 10.1088/1361-6382/ae3afa
Souvik Pramanik and Kumar Das
We have obtained the general form of even mode potential function for the gravitational perturbation of a static spherically symmetric spacetime and compared with known one in Schwarzschild limit. Considering the minimal-spread Gaussian matter source, parameterized by a smearing length scale Θ, the associated quasinormal mode (QNM) frequencies are computed numerically using the well known WKB formula. A comparative study on the accuracy of the results based on different approximation orders of the WKB formula indicates that the smearing parameter Θ has an upper bound, beyond which the spectra of odd and even modes deviate from their usual isospectral nature.
{"title":"Even parity potential for spacetimes with Gaussian matter source and its associated QNM spectra","authors":"Souvik Pramanik and Kumar Das","doi":"10.1088/1361-6382/ae3afa","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3afa","url":null,"abstract":"We have obtained the general form of even mode potential function for the gravitational perturbation of a static spherically symmetric spacetime and compared with known one in Schwarzschild limit. Considering the minimal-spread Gaussian matter source, parameterized by a smearing length scale Θ, the associated quasinormal mode (QNM) frequencies are computed numerically using the well known WKB formula. A comparative study on the accuracy of the results based on different approximation orders of the WKB formula indicates that the smearing parameter Θ has an upper bound, beyond which the spectra of odd and even modes deviate from their usual isospectral nature.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"159 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115690","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 : 2026-02-04DOI: 10.1088/1361-6382/ae3afd
Benito Rodríguez, I Díaz-Saldaña, Wilfredo Yunpanqui and Javier Chagoya
The main goal of this work is to investigate how relevant quantum gravity corrections can be, at an effective level, in the geometry describing the exterior of a black hole, and whether such corrections can be tested observationally. For this purpose, we employ Bozza’s method to calculate the deflection angle of light in presence of the strong gravitational field generated by an improved Schwarzschild-like black hole whose metric, regular throughout the entire spacetime, was derived using the improved generalized uncertainty principle (GUP). This framework incorporates effective quantum gravity corrections that resolve the physical singularity inside the black hole, quantified by a model parameter . In addition, the event horizon, the photon sphere, and the shadow radius receive modifications characterized by a second model parameter . Using observational properties of the supermassive black holes Messier 87 and Sagittarius A reported by the Event Horizon Telescope, we derive constraints on the parameter , namely . To the best of our knowledge, these are the first constraints reported in the literature for this improved GUP parameter. Since does not play a significant role in the correction of the shadow radius, it was not possible to impose restrictions on its allowed values, however, it is important to consider a non-zero in order to avoid a black hole singularity.
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