Classical and Quantum Gravity最新文献_第2页

Pseudo-supersymmetric approach to the Dirac operator in the Schwarzschild spacetime 施瓦兹柴尔德时空中狄拉克算子的伪超对称方法

Classical and Quantum Gravity Pub Date : 2024-06-06 DOI: 10.1088/1361-6382/ad550c

Ö. Yeşiltaş

引用次数: 0

Infinitely degenerate slowly rotating solutions in f(R) gravity f(R)引力中无限退化的缓慢旋转解

Classical and Quantum Gravity Pub Date : 2024-05-15 DOI: 10.1088/1361-6382/ad4c4b

Alan Sunny, Semin Xavier, S. Shankaranarayanan

{"title":"Infinitely degenerate slowly rotating solutions in f(R) gravity","authors":"Alan Sunny, Semin Xavier, S. Shankaranarayanan","doi":"10.1088/1361-6382/ad4c4b","DOIUrl":"https://doi.org/10.1088/1361-6382/ad4c4b","url":null,"abstract":"\u0000 This work tests the no-hair conjecture in f(R) gravity models. No-hair conjecture asserts that all black holes in General Relativity coupled to any matter must be Kerr–Newman type. However, the conjecture fails in some cases with non-linear matter sources. Here, we address this by explicitly constructing multiple slow-rotating black hole solutions, up to second order in rotational parameter, for a class of f(R) models ( f(R) =(alpha_{0} + alpha_{1},R)^{p}, p > 1). Such an f(R) includes all higher-powers of R. We analytically show that multiple vacuum solutions satisfy the field equations up to the second order in the rotational parameter. In other words, we show that the multiple vacuum solutions depend on arbitrary constants, which depend on the coupling parameters of the model. Hence, our results indicate that the no-hair theorem for modified gravity theories merits extending to include the coupling constants. The uniqueness of our result stems from the fact that these are obtained directly from metric formalism without conformal transformation. We discuss the kinematical properties of these black hole solutions and compare them with slow-rotating Kerr. Specifically, we show that the circular orbits for the black holes in f(R) are smaller than that of Kerr. This implies that the inner-most stable circular orbit for black holes in f(R) is smaller than Kerr's; hence, the shadow radius might also be smaller. Finally, we discuss the implications of our results for future observations.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140976126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Preliminary sensitivity study for a gravitational redshift measurement with China's Lunar Exploration Project 中国探月工程引力红移测量的初步灵敏度研究

Classical and Quantum Gravity Pub Date : 2024-05-13 DOI: 10.1088/1361-6382/ad4ae2

Chenggang Qin, Tong Liu, Xiao-Yi Dai, Peng-Bin Guo, Weisheng Huang, Xiang-Pei Liu, Yu-Jie Tan, Cheng-Gang Shao

{"title":"Preliminary sensitivity study for a gravitational redshift measurement with China's Lunar Exploration Project","authors":"Chenggang Qin, Tong Liu, Xiao-Yi Dai, Peng-Bin Guo, Weisheng Huang, Xiang-Pei Liu, Yu-Jie Tan, Cheng-Gang Shao","doi":"10.1088/1361-6382/ad4ae2","DOIUrl":"https://doi.org/10.1088/1361-6382/ad4ae2","url":null,"abstract":"\u0000 General relativity (GR) is a highly successful theory that describes gravity as a geometric phenomenon. The gravitational redshift, a classic test of GR, can potentially be violated in alternative gravity theories, and experimental tests on this effect are crucial for our understanding of gravity. In this paper, considering the space-ground clock comparisons with free-space links, we discuss a high-precision Doppler cancellation-based measurement model for testing gravitational redshift. This model can effectively reduce various sources of error and noise, reducing the influences of the first-order Doppler effect, atmospheric delay, Shapiro delay, etc. China's Lunar Exploration Project (CLEP) is proposed to equip the deep-space H maser with a daily stability of $2times10^{-15}$, which provides an approach for testing gravitational redshift. Based on the simulation, we analyze the space-ground clock comparison experiments of the CLEP experiment, and simulation analysis demonstrates that under ideal condition of high-precision measurement of the onboard H-maser frequency offset and drift, the CLEP experiment may reach the uncertainty of $3.7times10^{-6}$ after a measurement session of 60 days. Our results demonstrate that if the issue of frequency offset and drift is solved, CLEP missions have a potential of testing the gravitational redshift with high accuracy.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140984575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Deﬂection of Light by a Reissner-Nordström Black Hole and Painlevé VI equation 雷斯纳-诺德斯特伦黑洞对光的探测和潘列维 VI方程

Classical and Quantum Gravity Pub Date : 2024-05-13 DOI: 10.1088/1361-6382/ad4ae1

Tadashi Sasaki

{"title":"Deﬂection of Light by a Reissner-Nordström Black Hole and Painlevé VI equation","authors":"Tadashi Sasaki","doi":"10.1088/1361-6382/ad4ae1","DOIUrl":"https://doi.org/10.1088/1361-6382/ad4ae1","url":null,"abstract":"\u0000 We consider the bending angle of the trajectory of a photon incident from and deﬂected to inﬁnity around a Reissner-Nordström black hole. We treat the bending angle as a function of the squared reciprocal of the impact parameter and the squared electric charge of the background normalized by the mass of the black hole. It is shown that the bending angle satisﬁes a system of two inhomogeneous linear partial diﬀerential equations with polynomial coeﬃcients. This system can be understood as an isomonodromic deformation of the inhomogeneous Picard-Fuchs equation satisﬁed by the bending angle in the Schwarzschild spacetime, where the deformation parameter is identiﬁed as the background electric charge. Furthermore, the integrability condition for these equations is found to be a speciﬁc type of the Painlevé VI equation that allows an algebraic solution. We solve the diﬀerential equations both at the weak and strong deﬂection limits. In the weak deﬂection limit, the bending angle is expressed as a power series expansion in terms of the squared reciprocal of the impact parameter and we obtain the explicit full-order expression for the coeﬃcients. In the strong deﬂection limit, we obtain the asymptotic form of the bending angle that consists of the divergent logarithmic term and the ﬁnite O(1) term supplemented by linear recurrence relations which enable us to straightforwardly derive higher order coeﬃcients. In deriving these results, the isomonodromic property of the diﬀerential equations plays an important role. Lastly, we brieﬂy discuss the applicability of our method to other types of spacetimes such as a spinning black hole.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140984486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geometric interpretation of Tensor-Vector-Scalar theory in a Kaluza-Klein reference fluid 张量-矢量-标量理论在卡卢扎-克莱因参比流体中的几何解释

Classical and Quantum Gravity Pub Date : 2024-05-09 DOI: 10.1088/1361-6382/ad494e

Timothy Andersen

{"title":"Geometric interpretation of Tensor-Vector-Scalar theory in a Kaluza-Klein reference fluid","authors":"Timothy Andersen","doi":"10.1088/1361-6382/ad494e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad494e","url":null,"abstract":"\u0000 Gravitational alternatives to dark matter require additional fields or assumptions beyond general relativity while continuing to agree with tight solar system constraints. Modified Newtonian Dynamics (MOND), for example, predicts the Tully-Fisher relation for galaxies more accurately than dark matter models while limiting to Newtonian gravity in the solar system. On the other hand, MOND does a poor job predicting larger scale observations such as the Cosmic Microwave Background and Matter Power Spectra. Tensor-Vector-Scalar (TeVeS) theory is a relativistic generalization of MOND that accounts for these observations without dark matter. In this paper, I derive a generalized TeVeS from Kaluza-Klein theory in one extra dimension as a consequence of $n=0$ Kaluza-Klein modes. In the KK theory, MOND is a special case of a slicing condition in the 5D ADM formalism enforced by a reference fluid as in the Isham-Kuchav{r} method which may arise from a broken displacement symmetry. This has two benefits: first is means that TeVeS is compatible with Kaluza-Klein dark matter theory, which is a strong candidate for Weakly Interacting Massive Particles (WIMPs), the other is that it provides an elegant mechanism for the scalar and vector fields. It constrains most of the freedom in the definition of TeVeS which does not have a field theoretic motivation. This is important because the Kaluza-Klein theory predicts that spin-2 tensor modes must propagate at the speed of light, in agreement with observation, from theoretical constraints while TeVeS has to match this observation empirically. Furthermore, it removes need for the interpolating function in MOND and the Lorentz-violating condition on the vector field to be physical since they are analogous to a gauge condition and depend on state of motion.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140994560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Scalar Perturbations in Nonsingular Universes from Interacting Vacuum 来自相互作用真空的非星际宇宙中的标量扰动

Classical and Quantum Gravity Pub Date : 2024-05-09 DOI: 10.1088/1361-6382/ad494d

Rodrigo Maier, Filipe Cattete Alves

引用次数: 0

New generation of Superattenuator for Einstein Telescope: preliminary studies 用于爱因斯坦望远镜的新一代超级衰减器：初步研究

Classical and Quantum Gravity Pub Date : 2024-04-18 DOI: 10.1088/1361-6382/ad407e

A. Bertocco, M. Bruno, Rosario De Rosa, L. Di Fiore, Domenico D'Urso, F. Frasconi, A. Gennai, L. Lucchesi, M. Refat, F. Pilo, D. Rozza, P. Ruggi, V. Sipala, I. Tosta e Melo, L. Trozzo

{"title":"New generation of Superattenuator for Einstein Telescope: preliminary studies","authors":"A. Bertocco, M. Bruno, Rosario De Rosa, L. Di Fiore, Domenico D'Urso, F. Frasconi, A. Gennai, L. Lucchesi, M. Refat, F. Pilo, D. Rozza, P. Ruggi, V. Sipala, I. Tosta e Melo, L. Trozzo","doi":"10.1088/1361-6382/ad407e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad407e","url":null,"abstract":"\u0000 Seismic noise and local disturbances are dominant noise sources for ground-based Gravitational Waves detectors in the low frequency region (0.1 to 10 Hz) limiting their sensitivity and duty cycle. With the introduction of high-performance seismic isolation systems based on mechanical pendula, the 2nd generation laser interferometric detectors have reached the scientific goal of the first direct observation of GW signals thanks to the extension of the detection bandwidth down to 10 Hz. Now, the 3rd generation instrument era is approaching, and the Einstein Telescope giant interferometer is becoming a reality with the possibility to install the detector in an underground site where seismic noise is 100 times smaller than on surface. Moreover, new available technologies as well as the experience acquired in operating advanced detectors are key points to further extend the detection bandwidth down to 2 Hz with the possibility to suspend cryogenic payload and then mitigating Thermal Noise too. Here, we present a preliminary study devoted to improving seismic attenuation performance of the Advanced VIRGO Superattenuator in the low frequency region of about five orders of magnitude. Particular care has been carried on in analyzing the possibility to improve the vertical attenuation performance with a multi-stage pendulum chain equipped with magnetic anti-springs that is hung to a double Inverted Pendulum in nested configuration. The feedback control requirements and possible strategies to be adopted for this last element will be presented.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140688124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ar transport and blister growth kinetics in titania-doped germania-based optical coatings 掺杂二氧化钛的锗基光学镀膜中的氩传输和砂眼生长动力学

Classical and Quantum Gravity Pub Date : 2024-04-17 DOI: 10.1088/1361-6382/ad3ffb

É. Lalande, Aaron Davenport, Lory Marchand, Ashot Markosyan, Daniel Martinez, A. Paolone, M. Rezac, M. Bazzan, M. Chicoine, Julien Colaux, Matthieu Coulon, M. Fejer, A. Lussier, E. Majorana, Ludvik Martinu, Carmen Menoni, Christophe Michel, Fulvio Ricci, F. Schiettekatte, Nikita Shcheblanov, Joshua R Smith, J. Teillon, G. Terwagne, G. Vajente

{"title":"Ar transport and blister growth kinetics in titania-doped germania-based optical coatings","authors":"É. Lalande, Aaron Davenport, Lory Marchand, Ashot Markosyan, Daniel Martinez, A. Paolone, M. Rezac, M. Bazzan, M. Chicoine, Julien Colaux, Matthieu Coulon, M. Fejer, A. Lussier, E. Majorana, Ludvik Martinu, Carmen Menoni, Christophe Michel, Fulvio Ricci, F. Schiettekatte, Nikita Shcheblanov, Joshua R Smith, J. Teillon, G. Terwagne, G. Vajente","doi":"10.1088/1361-6382/ad3ffb","DOIUrl":"https://doi.org/10.1088/1361-6382/ad3ffb","url":null,"abstract":"\u0000 Blistering is a phenomenon sometimes observed in sputtered-deposited thin films but seldom investigated in detail. Here, we consider the case of titania-doped germania (TGO)/silica multi-layers deposited by ion beam sputtering. TGO is a candidate as high refractive index material in the Bragg mirrors for the next iteration of gravitational waves detectors. It needs to be annealed at 600°C for 100h in order to reach the desired relaxation state. However under some growth conditions, in 52-layer TGO/silica stacks, blistering occurs upon annealing at a temperature near 500°C, which corresponds to the temperature where Ar desorbs from TGO. In order to better understand the blistering phenomenon, we measure the Ar transport in single layers of TGO and silica. In the case of <1 μm-thick TGO layers, the Ar desorption is mainly limited by detrapping. The transport model also correctly predicts the evolution of the total amount of Ar in a 8.5 μm stack of TGO and silica layers annealed at 450°C, but in that case, the process is mainly limited by diffusion. Since Ar diffusion is an order of magnitude slower in TGO compared to silica, we observe a correspondingly strong accumulation of Ar in TGO. The Ar transport model is used to explain some regimes of the blisters growth, and we find indications that Ar accumulation is a driver for their growth in general, but the blisters nucleation remains a complex phenomenon influenced by several other factors including stress, substrate roughness, and impurities.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140692405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Algebraic classiﬁcation of 2+1 geometries: a new approach 2+1 几何图形的代数分类：一种新方法

Classical and Quantum Gravity Pub Date : 2024-04-17 DOI: 10.1088/1361-6382/ad3ffd

M. Papajčı́k, J. Podolský

{"title":"Algebraic classiﬁcation of 2+1 geometries: a new approach","authors":"M. Papajčı́k, J. Podolský","doi":"10.1088/1361-6382/ad3ffd","DOIUrl":"https://doi.org/10.1088/1361-6382/ad3ffd","url":null,"abstract":"\u0000 We present a convenient method of algebraic classification of 2+1 spacetimes into the types I, II, D, III, N and O, without using any field equations. It is based on the 2+1 analogue of the Newman-Penrose curvature scalars Psi_A of distinct boost weights, which are specific projections of the Cotton tensor onto a suitable null triad. The algebraic types are then simply determined by the gradual vanishing of such Cotton scalars, starting with those of the highest boost weight. This classification is directly related to the specific multiplicity of the Cotton-aligned null directions (CANDs) and to the corresponding Bel-Debever criteria. Using a bivector (that is 2-form) decomposition, we demonstrate that our method is fully equivalent to the usual Petrov-type classification of 2+1 spacetimes based on the eigenvalue problem and determining the respective canonical Jordan form of the Cotton-York tensor. We also derive a simple synoptic algorithm of algebraic classification based on the key polynomial curvature invariants. To show the practical usefulness of our approach, we perform the classification of several explicit examples, namely the general class of Robinson-Trautman spacetimes with an aligned electromagnetic field and a cosmological constant, and other metrics of various algebraic types.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140690394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optical properties of germania and titania at 1064 nm and at 1550 nm 1064 纳米和 1550 纳米波长下的锗和二氧化钛的光学特性

Classical and Quantum Gravity Pub Date : 2024-04-09 DOI: 10.1088/1361-6382/ad3c8c

Diksha Diksha, Alex Amato, V. Spagnuolo, Graeme McGhee, M. Chicoine, Caspar Clark, Stuart Hill, J. Hough, Ross Johnston, Remy Keil, Nena Mavridi, S. Reid, Sheila Rowan, Timon Schapals, F. Schiettekatte, Simon Tait, Iain W Martin, J. Steinlechner

{"title":"Optical properties of germania and titania at 1064 nm and at 1550 nm","authors":"Diksha Diksha, Alex Amato, V. Spagnuolo, Graeme McGhee, M. Chicoine, Caspar Clark, Stuart Hill, J. Hough, Ross Johnston, Remy Keil, Nena Mavridi, S. Reid, Sheila Rowan, Timon Schapals, F. Schiettekatte, Simon Tait, Iain W Martin, J. Steinlechner","doi":"10.1088/1361-6382/ad3c8c","DOIUrl":"https://doi.org/10.1088/1361-6382/ad3c8c","url":null,"abstract":"\u0000 One of the main noise sources in current gravitational wave detectors is the thermal noise of the high-reflectivity coatings on the main interferometer optics. Coating thermal noise is dominated by the mechanical loss of the high-refractive index material within the coating stacks, Ta2O5 mixed with TiO2. For upgrades to room-temperature detectors, a mixture of GeO2 and TiO2 is an interesting alternative candidate coating material. While the rather low refractive index of GeO2 increases with increasing TiO2 content, a higher TiO2 content results in a lower threshold temperature before heat treatment leads to crystallisation, and potentially to a degradation of optical properties. For future cryogenic detectors, on the other hand, a higher TiO2 content is beneficial as the TiO2 suppresses the low-temperature mechanical loss peak of GeO2. In this paper, we present the optical properties of coatings -- produced by plasma-assisted ion-beam evaporation -- with high TiO2 content at 1550nm, a laser wavelength considered for cryogenic gravitational-wave detectors, as a function of heat-treatment temperature. For comparison, the absorption was also measured of pure GeO2. Furthermore, results at the currently-used wavelength of 1064nm are presented.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140725535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0