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Fluid and Scalar Field Representations in the Brans–Dicke Theory: Cosmological Scenarios 布兰斯-迪克理论中的流体和标量场表示：宇宙学情景
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700537
Tiago H. B. Alves, Júlio C. Fabris, Luiz Filipe Guimarães
{"title":"Fluid and Scalar Field Representations in the Brans–Dicke Theory: Cosmological Scenarios","authors":"Tiago H. B. Alves,&nbsp;Júlio C. Fabris,&nbsp;Luiz Filipe Guimarães","doi":"10.1134/S0202289325700537","DOIUrl":"10.1134/S0202289325700537","url":null,"abstract":"<p>The Brans–Dicke scalar-tensor cosmological models are studied in both Einstein and Jordan frames, using a hydrodynamical and self-interacting scalar field representations of the energy-momentum tensor leading to the same background solutions. The main features of the corresponding cosmological scenarios are determined. In many cases, the interpolation of decelerating and accelerating regimes are identified. Furthermore, the characteristics of solutions with attractive gravity are analyzed, determining possible implications for Brans–Dicke gravitation theory in the present scenario. The properties of the self-interacting scalar field, including the corresponding potential, are determined. Some possible appealing configurations are identified for the matter content like pressureless <span>((alpha=0))</span>, cosmological constant <span>((alpha={-}1))</span> and phantom matter <span>((alpha={-}2))</span>. The phantom case is motivated by some observational results like those obtained by the DESI project.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"50 - 59"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
A Note on Pure Connection Formalism for Unimodular Gravity and Its Possible Generalizations 关于非模引力的纯连接形式及其可能推广的注记
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700562
Alexey L. Smirnov
{"title":"A Note on Pure Connection Formalism for Unimodular Gravity and Its Possible Generalizations","authors":"Alexey L. Smirnov","doi":"10.1134/S0202289325700562","DOIUrl":"10.1134/S0202289325700562","url":null,"abstract":"<p>In this note, we consider the Henneaux–Teitelboim version of Unimodular Gravity (UG) and its deformations in the form of gauge theories with spontaneously broken diffeomorphism invariance. The actions defining such theories depends on the curvature of an <span>(SO(3,mathbb{C}))</span> gauge connection and the field strength of a (real) 3-form (or equivalently its dual vector density). We obtain the pure connection action of the theory from the corresponding Plebanski action by integrating out auxiliary fields. Then we show that the Henneaux–Teitelboim form of UG can be included in a wider class of theories which propagate two (complex) degrees of freedom.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"87 - 92"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Impact of Pressure Anisotropy on a Compact Stellar Model in General Relativity 广义相对论中压力各向异性对致密恒星模型的影响
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700628
Rinkal Patel
{"title":"Impact of Pressure Anisotropy on a Compact Stellar Model in General Relativity","authors":"Rinkal Patel","doi":"10.1134/S0202289325700628","DOIUrl":"10.1134/S0202289325700628","url":null,"abstract":"<p>We present a new class of singularity-free interior solutions for anisotropic compact stars with spherical symmetry. By prescribing a specific pressure anisotropy, exact solutions to Einstein’s field equations are obtained and matched smoothly to the Schwarzschild exterior metric. The model parameters are determined using the boundary condition of vanishing radial pressure. The physical viability of the model is demonstrated through an analysis of the pulsar 4U1820-30, characterized by a radius of 9.1 km and mass <span>(M=1.58M_{odot}.)</span>\u0000 </p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"164 - 173"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147559437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Scalar Field Dark Energy Model Via Observational Constraints 观测约束下的标量场暗能量模型
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700550
Aroonkumar Beesham, Alfred Mvunyelwa Msomi, Sfundo Cebolenkosi Gumede
{"title":"Scalar Field Dark Energy Model Via Observational Constraints","authors":"Aroonkumar Beesham,&nbsp;Alfred Mvunyelwa Msomi,&nbsp;Sfundo Cebolenkosi Gumede","doi":"10.1134/S0202289325700550","DOIUrl":"10.1134/S0202289325700550","url":null,"abstract":"<p>This paper proposes a new scalar field cosmological model aimed at studying the late-time acceleration of the universe, based on a parametrization of the deceleration parameter. The main objective is to constrain fundamental cosmological parameters by integrating the latest measurements of the Hubble parameter from various observational datasets, including BAO, BAO <span>(+)</span> R19, CC <span>(+)</span> SC <span>(+)</span> BAO, and CC <span>(+)</span> SC <span>(+)</span> BAO <span>(+)</span> R19 from recent galaxy surveys. With a redshift range covering <span>(0.106&lt;z&lt;2.33)</span>, and incorporating the newest Hubble constant measurements from Riess et al. in 2019, we acquire best-fit parameter values for <span>(H_{0})</span> and <span>(r_{d})</span>. It is noteworthy that within late-time observations of <span>(H_{0})</span>, we observe a significant discrepancy, reproducing the reported <span>(H_{0})</span> tension. While our model is in good agreement with both the joint analysis and analysis with R19, discrepancies arise when BAO and BAO with R19 datasets are gradually included. Our model provides an excellent fit to the observed data and is consistent with the standard <span>(Lambda)</span>CDM paradigm at higher redshifts. However, the most interesting aspect is the prediction of future super-accelerated expansion, in contrast to the de Sitter phase predicted by the <span>(Lambda)</span>CDM model. The unique behavior of the jerk parameter also hints at new dynamics as ccompared to traditional cosmological models.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"70 - 86"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
New Relativistic Cosmology Based on Principle of Scale Invariance# 基于尺度不变性原理的新相对论宇宙论#
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700495
A. S. Rabinowitch
{"title":"New Relativistic Cosmology Based on Principle of Scale Invariance#","authors":"A. S. Rabinowitch","doi":"10.1134/S0202289325700495","DOIUrl":"10.1134/S0202289325700495","url":null,"abstract":"<p>Modern cosmology faces a large number of unsolved questions. These include the problem of cosmological singularity, the lack of explanations for the nature of dark matter, the existence of well-developed galaxies in the few hundred million years after the Big Bang, and a number of other questions. In this regard, a different approach to constructing cosmology is proposed. It examines a generalization of General Relativity based on Weyl’s principle of scale invariance. This generalization allows one to arrive at a nonstandard cosmological solution in which the Big Bang is absent. Its application leads to new explanations for the redshift in the spectra of distant galaxies and the cosmic microwave background, as well as to a new view on the nature of dark matter.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"7 - 13"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Geometrization of Physics: The Problem of Motion 物理学的几何化：运动问题
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700574
Magd E. Kahil
{"title":"Geometrization of Physics: The Problem of Motion","authors":"Magd E. Kahil","doi":"10.1134/S0202289325700574","DOIUrl":"10.1134/S0202289325700574","url":null,"abstract":"<p>The geometrization of physics may be expressed in the context of finding equations of motion for different objects rather than the conventional concept of allocating field variables geometrically. This can be performed by identifying physical quantities in terms of scalars, vectors and tensors described in various geometries that admit a nonvanishing curvature and torsion of space-time. The effect of covariant differentiation may represent the effect of physical fields on the trajectory of objects. We adopt a method in which spinning and charged objects are expressed using a parameter transformation between two nearby paths separated by a deviation vector in Riemannian, non-Riemannian, and Finslerian geometries. Moreover, the concept of parameter transformation is being revisited in the context of Clifford space as a step of combining microphysics and macrophysics.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"93 - 107"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Selection of the Valid Gravitation Theory from Observations of Black Hole Images({}^{sharp}) 从黑洞图像观测中选择有效的引力理论({}^{sharp})
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700501
V. I. Dokuchaev, K. E. Prokopev
{"title":"Selection of the Valid Gravitation Theory from Observations of Black Hole Images({}^{sharp})","authors":"V. I. Dokuchaev,&nbsp;K. E. Prokopev","doi":"10.1134/S0202289325700501","DOIUrl":"10.1134/S0202289325700501","url":null,"abstract":"<p>A fast progress in the observational technologies in astrophysics provides a unique possibility for detailed observations of black holes in the nearest future. It will be possible to verify general relativity (GR) and its numerous modifications in the strong field limit by using observational data from advanced cosmic interferometric observatories. We review the modeled images of a rotating black hole in different appropriate cases: a luminous distant background, a thin accretion disk, and a luminous moving hot spots in relativistic jets along the black hole rotation axis. Detailed observations of astrophysical supermassive black holes SgrA* and M87* will be possible within the nearest 10 years by using the Millimetron Space Observatory proposed and developed by domestic scientists.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"14 - 17"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147559427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Nonlinear Electrodynamic Bending of Hard Radiation Rays in the Eletromagnetic Field of a Relativistically Rotating Pulsar 相对旋转脉冲星电磁场中硬辐射的非线性电动力弯曲
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700525
Moldir S. Seidaliyeva, Victor I. Denisov, Irene P. Denisova
{"title":"Nonlinear Electrodynamic Bending of Hard Radiation Rays in the Eletromagnetic Field of a Relativistically Rotating Pulsar","authors":"Moldir S. Seidaliyeva,&nbsp;Victor I. Denisov,&nbsp;Irene P. Denisova","doi":"10.1134/S0202289325700525","DOIUrl":"10.1134/S0202289325700525","url":null,"abstract":"<p>The propagation of X-ray or gamma-ray radiation in the electromagnetic field of a relativistically rotating pulsar is studied within the framework of vacuum nonlinear electrodynamics (NED). Metric tensors are constructed, along the geodesics along which two normal waves propagate in the strong electromagnetic field of a relativistically rotating pulsar. The laws of motion of two X-ray or gamma-ray pulses carried by these normal waves are indicated in a parametric form. The parameter in a specially selected coordinate system is the <span>(z)</span> coordinate. Tangent vectors to the rays are constructed, and the laws of ray curvature are investigated with their help when the <span>(z)</span> parameter changes from the point of emission of X-ray or gamma-ray pulses to the detector. It is shown that these rays are bent in two mutually perpendicular planes. This circumstance leads to a modification of the NED lensing effect compared to the NED lensing observed in the electromagnetic field of a slowly rotating pulsar.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"42 - 49"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
A Note on Twisted Spacetimes 关于扭曲时空的笔记
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700549
Uday Chand De, Sudhakar Kumar Chaubey
{"title":"A Note on Twisted Spacetimes","authors":"Uday Chand De,&nbsp;Sudhakar Kumar Chaubey","doi":"10.1134/S0202289325700549","DOIUrl":"10.1134/S0202289325700549","url":null,"abstract":"<p>Twisted space-times are logical extensions of Friedmann cosmological models, Lorentz–Minkowski space-times, Einstein-de Sitter space-times, generalized Robertson–Walker (GRW) space-times, and static Einstein space-times. The purpose of this manuscript is to investigate the characteristics of twisted space-times that are almost pseudo-Ricci symmetric (briefly, A(PRS)<span>({}_{n})</span>). We establish the sufficient conditions under which A(PRS)<span>({}_{n})</span> twisted space-times are GRW space-times, and under which A(PRS)<span>({}_{n})</span> space-times are twisted space-times. The necessary and sufficient condition for A(PRS)<span>({}_{n})</span> twisted space-times to be perfect fluid space-times is derived. We also prove that the vorticity and shear of A(PRS)<span>({}_{n})</span> twisted space-times filled with perfect fluid vanish identically. Consequently, we establish the equation of state and energy conditions. The non-existence of Ricci symmetric A(PRS)<span>({}_{n})</span> twisted space-times is ensured.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"60 - 69"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Investigating Anisotropic Spheres under (boldsymbol{f(R,T)}) Gravity in Karmarkar–Tolman Space-Time 研究Karmarkar-Tolman时空中(boldsymbol{f(R,T)})重力作用下的各向异性球体
IF 1 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2026-03-16 DOI: 10.1134/S0202289325700586
M. Ilyas, Fawad Khan, Sobia Khan, Ayesha Siddiqui, Rohna Iqbal, Natasha Saleem, Mona Mohamoud, Kottakkaran Sooppy Nisar, Abdel-Haleem Abdel-Aty
{"title":"Investigating Anisotropic Spheres under (boldsymbol{f(R,T)}) Gravity in Karmarkar–Tolman Space-Time","authors":"M. Ilyas,&nbsp;Fawad Khan,&nbsp;Sobia Khan,&nbsp;Ayesha Siddiqui,&nbsp;Rohna Iqbal,&nbsp;Natasha Saleem,&nbsp;Mona Mohamoud,&nbsp;Kottakkaran Sooppy Nisar,&nbsp;Abdel-Haleem Abdel-Aty","doi":"10.1134/S0202289325700586","DOIUrl":"10.1134/S0202289325700586","url":null,"abstract":"<p>The article probes exploration of the probable existence of relativistic compact celestial entities within a modified <span>(f(R,T))</span> theory. We employ the Karmarkar and Tolman solutions along with two noteworthy and sustainable forms of <span>(f(R,T))</span> gravity for an anisotropic distribution of matter. Within the solution of three relativistic compact star contenders, we opt for certain observational data to obtain the values of constants. We demonstrate a few physical characteristics of these relativistic compact celestial entities consisting of their formations, transverse and radial pressure, stability, anisotropy measure, energy density, EoS parameters and energy conditions.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"32 1","pages":"108 - 121"},"PeriodicalIF":1.0,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
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