Classical and Quantum Gravity最新文献

Monitoring the evolution of optical coatings during thermal annealing with real-time, in situ spectroscopic ellipsometry 利用实时原位光谱椭偏仪监测热退火过程中光学镀膜的演变情况

Classical and Quantum Gravity Pub Date : 2024-07-24 DOI: 10.1088/1361-6382/ad672c

Stefano Colace, Shima Samandari, M. Granata, Alex Amato, M. Caminale, Christophe Michel, G. Gemme, Laurent Pinard, Maurizio Canepa, M. Magnozzi

{"title":"Monitoring the evolution of optical coatings during thermal annealing with real-time, in situ spectroscopic ellipsometry","authors":"Stefano Colace, Shima Samandari, M. Granata, Alex Amato, M. Caminale, Christophe Michel, G. Gemme, Laurent Pinard, Maurizio Canepa, M. Magnozzi","doi":"10.1088/1361-6382/ad672c","DOIUrl":"https://doi.org/10.1088/1361-6382/ad672c","url":null,"abstract":"\u0000 Thermal annealing plays a key role in optimizing the properties of amorphous optical coatings. In the field of gravitational wave detection (GWD), however, the effects of annealing protocols on the interferometry mirror coatings have been explored primarily by ex post analysis. As a result, the dynamics of the coatings properties during annealing is still poorly known, potentially leading to suboptimal performance. Here, using real-time, in situ spectroscopic ellipsometry (SE) we have tracked the refractive index and thickness of a titania-tantala coating during controlled annealing. We have tested the material and the annealing protocol used in current GWD mirrors. The annealing cycle consisted of a heating ramp from room temperature to 500 °C, followed by a 10-hour plateau at the same temperature and the final cooling ramp. SE measurements have been run continuously during the entire cycle. Significant variations in the thickness and refractive index, which accompany the coating structural relaxation, have been recorded during the heating ramp. These variations start around 200 °C, slightly above the deposition temperature, and show an increased rate in the range 250-350 °C. A smaller, continuous evolution has been observed during the 10-hour high-temperature plateau. The results offer suggestions to modify the current annealing protocol for titania-tantala coatings, for example by increasing the time duration of the high-temperature plateau. They also suggest an increase in the substrate temperature at deposition. The approach presented here paves the way for systematic, real-time investigations to clarify how the annealing parameters shape the properties of optical coatings, and can be leveraged to define and optimize the annealing protocol of new candidate materials for GWD mirrors.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809666","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

A relativistic scalar model for fractional interaction between dark matter and gravity 暗物质与引力分数相互作用的相对论标量模型

Classical and Quantum Gravity Pub Date : 2024-07-23 DOI: 10.1088/1361-6382/ad66a8

Francesco Benetti, A. Lapi, G. Gandolfi, Stefano Liberati

{"title":"A relativistic scalar model for fractional interaction between dark matter and gravity","authors":"Francesco Benetti, A. Lapi, G. Gandolfi, Stefano Liberati","doi":"10.1088/1361-6382/ad66a8","DOIUrl":"https://doi.org/10.1088/1361-6382/ad66a8","url":null,"abstract":"\u0000 In a series of recent papers we put forward a “fractional gravity” framework striking an intermediate course between a modified gravity theory and an exotic dark matter (DM) scenario, which envisages the DM component in virialized halos to feel a non-local interaction mediated by gravity. The remarkable success of this model in reproducing several aspects of DM phenomenology motivates us to look for a general relativistic extension. Specifically, we propose a theory, dubbed Relativistic Scalar Fractional Gravity or RSFG, in which the trace of the DM stressenergy tensor couples to the scalar curvature via a non-local operator constructed with a fractional power of the d’Alembertian. We derive the field equations starting from an action principle, and then we investigate their weak field limit, demonstrating that in the Newtonian approximation the fractional gravity setup of our previous works is recovered. We compute the first-order post-Newtonian parameter γ and its relation with weak lensing, showing that although in RSFG the former deviates from its GR values of unity, the latter is unaffected. We also perform a standard scalar-vectortensor-decomposition of RSFG in the weak field limit, to highlight that gravitational waves propagate at the speed of light, though also an additional scalar mode becomes dynamical. Finally, we derive the modified conservation laws of the DM stress energy tensor in RSFG, showing that a new non-local force emerges, and hence that the DM fluid deviates from the geodesic solutions of the field equations.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141812844","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

Role of complexity on the minimal deformation of black holes 复杂性对黑洞最小变形的作用

Classical and Quantum Gravity Pub Date : 2024-07-15 DOI: 10.1088/1361-6382/ad6389

Z. Yousaf, K. Bamba, Bander Almutairi, S. Khan, M. Z. Bhatti

{"title":"Role of complexity on the minimal deformation of black holes","authors":"Z. Yousaf, K. Bamba, Bander Almutairi, S. Khan, M. Z. Bhatti","doi":"10.1088/1361-6382/ad6389","DOIUrl":"https://doi.org/10.1088/1361-6382/ad6389","url":null,"abstract":"\u0000 We investigate spherically symmetric classes of anisotropic solutions within the realm of a schematic gravitational decoupling scheme, primarily decoupling through minimal geometric deformation, applied to non-rotating, ultra-compact, self-gravitational fluid distributions. In this respect, we employ the minimal complexity factor scheme to generate physically realistic models for anisotropic matter distributions, using a well-behaved model. The zero-complexity factor condition enables us to determine the deformation function for solving the decoupled system. We explore all the structure-defining scalar variables, such as density inhomogeneity, strong energy condition, density homogeneity, and the complexity factor (an alloy of density inhomogeneity and pressure anisotropy) for the decoupling constant ranging between $0$ and $1$. We observe that the anisotropy vanishes when the coupling constant is set to unity. This finding holds significance as it implies that, in the context of a zero-complexity factor approach, an anisotropic matter distribution becomes perfect without requiring any isotropy requirements. This work effectively explored the impact of complexity on the composition of self-gravitational stellar distributions. This effective approach enables the development of new, physically realistic isotropic stellar models for anisotropic matter distributions. Additionally, our findings indicate that the complexity factor in static, spherically symmetric self-gravitational objects can significantly affect the nature of the matter distribution within these systems. It is concluded that the minimally deformed Durgapal-IV model features an increasing pressure profile, and the local anisotropy of pressure vanishes throughout the model under complexity-free conditions.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141648627","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

Imprints of the operator ordering ambiguity on the dynamics of perfect fluid dominated quantum universe 算子排序模糊性对完美流体主导量子宇宙动力学的影响

Classical and Quantum Gravity Pub Date : 2024-07-15 DOI: 10.1088/1361-6382/ad638a

Harkirat Singh Sahota

引用次数: 0

Axialgravisolitons at infinite corner 无限角的轴向游离基团

Classical and Quantum Gravity Pub Date : 2024-07-10 DOI: 10.1088/1361-6382/ad61b5

Federico Manzoni

{"title":"Axialgravisolitons at infinite corner","authors":"Federico Manzoni","doi":"10.1088/1361-6382/ad61b5","DOIUrl":"https://doi.org/10.1088/1361-6382/ad61b5","url":null,"abstract":"\u0000 Gravitational solitons (gravisolitons) are particular exact solutions of Einstein field equation in vacuum build on a given background solution. Their interpretation is not yet fully clear but they contain many of the physically relevant solutions low N-solitons solutions. However, a systematic study and characterization of gravisolitons solution for every N is lacking and their relevance in a theory of quantum gravity is not fully understood. This work aims to investigate and characterize some properties of N-axialsoliton solutions such as their asymptotically behaviour and asymptotic symmetries given minimal assumptions on the background metric. We develop an explicit systematic asymptotically expansion for the N-axialsoliton solution and we compute the leading order of the asymptotic killing vectors. Moreover, in the perspective to better understand the role of gravisolitons in quantum gravity we make a link, and a one of the first explicit test, to the corner symmetry proposal deriving which subalgebra of the universal corner symmetry algebra is generated by the asymptotic Killing vectors of N-axialsoliton solution. In the spirit of the corner proposal, the axialgravisoliton corner symmetry algebra (agcsa) can be useful for the quantization of the non-asymptotically flat sector of gravity while, in the spirit of IR triangle, new soft theorems and memory effects could emerge.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661259","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 ﬁelds around a rotating loop quantum gravity black hole: Waveform, quasi-normal modes and superradiance 旋转环量子引力黑洞周围的标量场：波形、准正常模式和超辐照度

Classical and Quantum Gravity Pub Date : 2024-07-09 DOI: 10.1088/1361-6382/ad6129

Zhong-Wu Xia, Hao Yang, Yan-Gang Miao

{"title":"Scalar ﬁelds around a rotating loop quantum gravity black hole: Waveform, quasi-normal modes and superradiance","authors":"Zhong-Wu Xia, Hao Yang, Yan-Gang Miao","doi":"10.1088/1361-6382/ad6129","DOIUrl":"https://doi.org/10.1088/1361-6382/ad6129","url":null,"abstract":"\u0000 The rotating loop quantum gravity black hole is a newly proposed non-singular black hole, which eliminates spacetime singularities owing to the introduction of a regular parameter through loop quantum corrections. This regular parameter leads to many observable effects. In this paper, the dynamical behavior of a scalar field near a rotating loop quantum gravity black hole is investigated. Given a small initial perturbation by a massless scalar field, we obtain the waveform of the massless scalar field evolving over time. By analyzing the waveform, we find that the regular parameter only affects the decaying oscillation of waveform, which is mainly described by quasi-normal modes. Moreover, we calculate the quasi-normal modes of a massive scalar field by three numerical methods, which are the Prony, WKB, and shooting methods, respectively. Our results indicate that the regular parameter has a significant influence on quasi-normal modes, but the loop quantum black holes remain stable under scalar field perturbations. Finally, we study the amplification effect of rotating loop quantum gravity black holes on scalar fields, i.e., the superradiance effect. Our results indicate the existence of stronger superradiance around loop quantum gravity black holes than that around Kerr ones.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141664182","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: 1

Quantum group intertwiner space from quantum curved tetrahedron 来自量子弯曲四面体的量子群交织空间

Classical and Quantum Gravity Pub Date : 2024-07-04 DOI: 10.1088/1361-6382/ad5f71

Muxin Han, Chen-Hung Hsiao, Qiaoyin Pan

{"title":"Quantum group intertwiner space from quantum curved tetrahedron","authors":"Muxin Han, Chen-Hung Hsiao, Qiaoyin Pan","doi":"10.1088/1361-6382/ad5f71","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5f71","url":null,"abstract":"\u0000 In this paper, we develop a quantum theory of homogeneously curved tetrahedron geometry, by applying the combinatorial quantization to the phase space of tetrahedron shapes defined in cite{Haggard:2015ima}. Our method is based on the relation between this phase space and the moduli space of SU(2) flat connections on a 4-punctured sphere. The quantization results in the physical Hilbert space as the solution of the quantum closure constraint, which quantizes the classical closure condition $M_4M_3M_2M_1=1$, $M_nuin SU(2)$, for the homogeneously curved tetrahedron. The quantum group $mathcal{U}_q(mathfrak{su}(2))$ emerges as the gauge symmetry of a quantum tetrahedron. The physical Hilbert space of the quantum tetrahedron coincides with the Hilbert space of 4-valent intertwiners of $mathcal{U}_q(mathfrak{su}(2))$. In addition, we define the area operators quantizing the face areas of the tetrahedron and compute the spectrum. The resulting spectrum is consistent with the usual Loop-Quantum-Gravity area spectrum in the large spin regime but is different for small spins. This work closely relates to 3+1 dimensional Loop Quantum Gravity in presence of cosmological constant and provides a justification for the emergence of quantum group in the theory.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141680101","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

Particle and light motion in Lyra-Schwarzschild spacetime 天琴-施瓦兹柴尔德时空中的粒子和光运动

Classical and Quantum Gravity Pub Date : 2024-07-02 DOI: 10.1088/1361-6382/ad5e30

R. R. Cuzinatto, E. de Morais, Bruto Max Pimentel

{"title":"Particle and light motion in Lyra-Schwarzschild spacetime","authors":"R. R. Cuzinatto, E. de Morais, Bruto Max Pimentel","doi":"10.1088/1361-6382/ad5e30","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5e30","url":null,"abstract":"\u0000 In this paper we recall the static and spherically symmetric solution derived within LyST gravity. LyST stands for “Lyra Scalar-Tensor” and is a scalar-tensor proposal for the gravitational interaction modifying general relativity by adopting Lyra manifold as the spacetime substrate. Lyra manifold is characterized both by the metric tensor gµν(x) and the scale φ(x); the latter being an integral part of the definition of reference frame. In a previous work, we have launched the formal geometrical basis of LyST, we have proposed an associated action integral for the gravitational interaction, we have derived the ﬁeld equations generalizing Einstein ﬁeld equation, and we have solved these equation to obtain the generalized version of Schwarzschild line element in Lyra manifold. This lead us to Lyra-Schwarzschild spacetime, which is further explored in the present paper. Herein, the trajectories of test particles is thoroughly studied. This is done for both massive particles and massless particles. The geodesic equations are built and solved. The effective potential associated to the motion of these particles around the source is determined and characterized. The possible trajectories include gravitational capture, scattering, bounded orbits, stable and unstable circular orbits, near-horizon motion. The innermost circular orbit allowed for massive particles is determined and compared to the one predicted by GR. The last photon orbit is also calculated for Lyra-Schwarzschild metric. The equation for the periastron shift in the context of Lyra-Schwarzschild solution is constructed; its application to observational data could be useful to constrain the parameters typical of LyST, telling it apart from GR.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141686997","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

Comparative Analysis of Dark Energy Compact Stars in $f(T,mathcal{T})$ and $f(T)$ Gravity Theories via Conformally Flat Condition 通过共形平坦条件对比分析 $f(T,mathcal{T})$ 和 $f(T)$ 引力理论中的暗能量紧凑恒星

Classical and Quantum Gravity Pub Date : 2024-06-11 DOI: 10.1088/1361-6382/ad56f0

A. Ditta, G. Mustafa, S. Maurya, D. Sofuoğlu, Asif Mahmood

{"title":"Comparative Analysis of Dark Energy Compact Stars in $f(T,mathcal{T})$ and $f(T)$ Gravity Theories via Conformally Flat Condition","authors":"A. Ditta, G. Mustafa, S. Maurya, D. Sofuoğlu, Asif Mahmood","doi":"10.1088/1361-6382/ad56f0","DOIUrl":"https://doi.org/10.1088/1361-6382/ad56f0","url":null,"abstract":"\u0000 This manuscript is the first investigation of dark energy celestial phenomena in the modified gravity theory by examining dark energy compact stars within the context of modified $f(T,mathcal{T})$ gravity. In order to compare the outcomes of the $f(T,mathcal{T})$ and $f(T)$ gravity theories, the model $f(T,mathcal{T})=alpha T(r)+beta mathcal{T}(r)+phi$ is selected. This model is then simplified to $f(T)$ gravity by setting $beta=0$. The $f(T)$ gravity is torsion-based gravity, while in $f(T,mathcal{T}$) gravity trace of energy-momentum tensor is coupled with torsion. Moreover, we note that we have more dense object formation in $f(T,mathcal{T})$ gravity as compared to $f(T$)-gravity. The spherically symmetric space-time inside the internal geometry is analyzed using a conformally flat condition, while the Schwarzschild geometry represents the outer space-time. Numerous characteristics of dark energy stars are examined, including equation of state components, energy conditions, and dark energy pressure components. Empirical evidence for the existence of dark energy in stellar configurations is presented by the results for pressure components in dark energy, which show a significant negative tendency in these stellar parameters. A complete analysis is performed by thoroughly investigating energy conditions, pressure profiles, sound speeds, gradients, adiabatic index, TOV equation, mass function, compactness, and redshift function. The mass-radius relation is also discussed via $M-R$ curves. This confirms that the studied star configuration is realistic and acceptable.","PeriodicalId":505126,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141359410","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

Superspace worldline formalism approach to Quantum Gravity: dimensional reduction and Holography 量子引力的超空间世界线形式主义方法：降维与全息

Classical and Quantum Gravity Pub Date : 2024-06-11 DOI: 10.1088/1361-6382/ad56ef

Jean-Baptiste Roux

引用次数: 0