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Models of (boldsymbol{f(Q)}) Gravity with Electromagnetic Field 的模型带电磁场的万有引力
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700543
S. H. Shekh, Hira Sohail, Irfan Mahmood, Allah Ditta, Anil Kumar Yadav, Suresh Parekh
{"title":"Models of (boldsymbol{f(Q)}) Gravity with Electromagnetic Field","authors":"S. H. Shekh,&nbsp;Hira Sohail,&nbsp;Irfan Mahmood,&nbsp;Allah Ditta,&nbsp;Anil Kumar Yadav,&nbsp;Suresh Parekh","doi":"10.1134/S0202289324700543","DOIUrl":"10.1134/S0202289324700543","url":null,"abstract":"<p>There are so many ideas that potentially explain the dark energy phenomenon, current research is focusing on a more in-depth analysis of the potential effects of modified gravity on both local and cosmic scales. In this paper we investigate some cosmic reconstructions in <span>(f(Q))</span> cosmology, where <span>(Q)</span> is the nonmetricity corresponding to the evolution background in the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. This allows us to determine how any FLRW cosmology can emerge from a particular <span>(f(Q))</span> theory. We employ the reconstruction technique to generate explicit formulations of the <span>(f(Q))</span> Lagrangian for several types of matter sources like a perfect fluid, a dustlike fluid, stiff fluid and a binary mixture of two fluids. Furthermore, we compute the field equations and the equation of state (EoS) parameter <span>(omega)</span> for two different reconstructed <span>(f(Q))</span> models with variation of the involved constants, which gives a scenario of an accelerating universe, a quintessence region and the cosmological constant. We also observe that the time dependence of <span>(omega)</span> admits cosmic acceleration. These new <span>(f(Q))</span> gravity inspired models may have an impact on gravitational phenomena at other cosmological scales.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"113 - 124"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529930","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
Compact Star Modeling of Durgapal Solution in (boldsymbol{f(Q)}) Gravity Durgapal 解决方案的紧凑星体建模((boldsymbol{f(Q)})引力
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700531
Akanksha Singh, S. K. Maurya, Sacheendra Shukla
{"title":"Compact Star Modeling of Durgapal Solution in (boldsymbol{f(Q)}) Gravity","authors":"Akanksha Singh,&nbsp;S. K. Maurya,&nbsp;Sacheendra Shukla","doi":"10.1134/S0202289324700531","DOIUrl":"10.1134/S0202289324700531","url":null,"abstract":"<p>This study uses a specific ansatz within <span>(f(Q))</span> gravity theory to examine the characteristics of spherically symmetric anisotropic compact stars. The research aims at enhance comprehension of these atypical entities by examining the physical properties of the compact star model using the Durgapal geometry within the context of <span>(f(Q))</span> gravity. The <span>(f(Q))</span> gravity field equations are resolved using the Karmarkar condition, and the physical characteristics such as density and pressure are computed for the resulting solution. The energy criteria are fulfilled, and the TOV equations perform the equilibrium analysis. The physical study indicates that our models meet the requirements for a well-behaved stellar system. This indicates that our solution is suitable for modeling astrophysical objects.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"99 - 112"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529929","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
Studies of the Inhomogeneous Cosmology in Higher Dimensional Space-Time with a Cosmological Constant
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S020228932470049X
D. Panigrahi, S. Chatterjee
{"title":"Studies of the Inhomogeneous Cosmology in Higher Dimensional Space-Time with a Cosmological Constant","authors":"D. Panigrahi,&nbsp;S. Chatterjee","doi":"10.1134/S020228932470049X","DOIUrl":"10.1134/S020228932470049X","url":null,"abstract":"<p>We study an inhomogeneous cosmology in Kaluza–Klein space-time with a positive cosmological constant in a dust dominated era (<span>(p=0)</span>). Depending on an integration constant, we have derived two types of solutions. The dimensional reduction of the extra-dimensional scale factor is possible due to an inhomogeneity depending on the curvature of the metric for the positive cosmological constant in all solutions. The high value of entropy in the present observable universe and the possible matter leakage in 4D world due to reduction of the extra dimension are also discussed. Our solutions show an early decelerating and late accelerating nature of the universe. The findings are verified by the well-known Raychaudhuri equation.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"53 - 63"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530031","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
Existence and Physical Properties of Gradient Ricci–Yamabe Solitons
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700464
Sinem Güler, Fatma Karaca
{"title":"Existence and Physical Properties of Gradient Ricci–Yamabe Solitons","authors":"Sinem Güler,&nbsp;Fatma Karaca","doi":"10.1134/S0202289324700464","DOIUrl":"10.1134/S0202289324700464","url":null,"abstract":"<p>We first prove the existence of the gradient Ricci–Yamabe soliton (briefly GRYS) by constructing an explicit example endowed with the Robertson–Walker metric. Then we focus on the physical properties of the gradient Ricci–Yamabe solitons satisying Einstein’s field equations, under the assumptions of different subspaces of Gray’s decompositions. For instance, we prove that if a GRYS space-time satisfying Einstein’s field equations, in which the gradient of the potential function <span>(psi)</span> is a unit-timelike torse-forming vector field, belongs to the subspaces <span>(mathcal{B})</span> and <span>(mathcal{B}^{prime})</span>, then it is a Robertson–Walker space-time with vanishing shear and vorticity. Moreover, its possible local cosmological structures are of Petrov types I, D, or O. Finally, we obtain the equations of state of a perfect-fluid space-time admitting the GRYS whose velocity field is a unit-timelike Killing vector field.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"28 - 36"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530021","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
Can Ring-Shaped Structures form Due to the Instability of Vertical Perturbations in a Self-Gravitating Disk?
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700488
K. T. Mirtadjieva, C. N. Nuritdinov, F. U. Botirov, J. M. Ganiev
{"title":"Can Ring-Shaped Structures form Due to the Instability of Vertical Perturbations in a Self-Gravitating Disk?","authors":"K. T. Mirtadjieva,&nbsp;C. N. Nuritdinov,&nbsp;F. U. Botirov,&nbsp;J. M. Ganiev","doi":"10.1134/S0202289324700488","DOIUrl":"10.1134/S0202289324700488","url":null,"abstract":"<p>We study the question of whether the instability of the vertical perturbation mode of a self-gravitating disk can lead to the formation of a certain ring-shaped structure. Thus, we have discovered two modes of vertical perturbations. The gravitational instability of these perturbation modes is investigated below against the background of a radially pulsating disk model, which is a nonstationary generalization of the well-known Bisnovaty-Kogan–Zeldovich equilibrium model. The corresponding nonstationary analogues of the dispersion equation of these two modes of vertical perturbations are found. The results of the study are presented in the form of critical dependencies of the initial virial ratio on the disk rotation parameter. It is shown that with an increase in the disk’s degree of rotation, there decreases the range of the initial virial ratio at which ring structures can form. The initial physical conditions, criteria and the corresponding mechanisms for the formation of ring-shaped structures due to the instability of the bending mode of the vertical perturbation are determined. A comparative analysis of the gravitational instability increments of the annular horizontal and vertical perturbation modes is also carried out.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"46 - 52"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530030","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
Bondi Accretion onto a Damour–Solodukhin Wormhole
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700476
R. M. Yusupova, R. Kh. Karimov, A. Bhattacharya
{"title":"Bondi Accretion onto a Damour–Solodukhin Wormhole","authors":"R. M. Yusupova,&nbsp;R. Kh. Karimov,&nbsp;A. Bhattacharya","doi":"10.1134/S0202289324700476","DOIUrl":"10.1134/S0202289324700476","url":null,"abstract":"<p>The Damour–Solodukhin wormhole (hereinafter DSWH) is known to mimic a Schwarzschild black hole (hereinafter SBH) horizon in some properties. To act as a mimicker, the DSWH parameter <span>(lambda)</span> by definition is required to be extremely tiny, i.e., <span>(lambdasim 0)</span>. Our comparative analysis shows that such a requirement may be too restrictive at least as far as the Bondi accretion profiles of the two objects, the DSWH and SBH, are concerned. Intriguingly, it turns out that some profiles of a DSWH mimic those for the SBH near the horizon even at values of <span>(lambda)</span> considerably higher, i.e., <span>(lambdasim 1)</span>.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"37 - 45"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530032","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
Theoretical Analysis on QCD Ghost Dark Energy in the DGP Braneworld DGP 边界中 QCD 幽灵暗能量的理论分析
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S020228932470052X
Sibo Zhang, Weiqiang Yang
{"title":"Theoretical Analysis on QCD Ghost Dark Energy in the DGP Braneworld","authors":"Sibo Zhang,&nbsp;Weiqiang Yang","doi":"10.1134/S020228932470052X","DOIUrl":"10.1134/S020228932470052X","url":null,"abstract":"<p>We study the evolution of a QCD ghost dark energy model under two branches of the DGP braneworld, and this model is distinguished from the <span>(Lambda)</span>CDM model by diagnostic methods of Statefinder hierarchy and Om(<span>(z)</span>). Through the derivation of the evolution equation of the energy density parameters, the deceleration parameters and the equation-of-state (EoS) parameter, it can be proved that in both noninteractive and interactive scenarios (specifically, including <span>(Q_{1}=3Hxirho_{textrm{de}},Q_{2}=3Hxirho_{textrm{dm}},Q_{3}=3Hxi(rho_{textrm{de}}+rho_{textrm{dm}}))</span>), this model can well describe the evolution rule of today’s universe. In the later stage of the evolution of the universe, the main component of the universe changed from dark matter to dark energy, and the universe gradually transitioned from decelerating expansion to accelerating expansion, and it will not end up with a big rip in the future. And in the self-accelerating branch of the DGP braneworld, the accelerated expansion of the universe occurred earlier. In order to distinguish the QCD model from the <span>(Lambda)</span>CDM model, we adopted two diagnostic methods, namely, the Statefinder diagnostic and the Om diagnostic. From their respective diagnostic images, it can be seen that these two diagnostic methods cannot only effectively distinguish the QCD model from <span>(Lambda)</span>CDM, but also directly reflect that the coupling parameters <span>(xi)</span> have a certain impact on the dark energy model. It can also eliminate the degeneracy of different coupling parameters under the same interaction.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"82 - 98"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529927","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 Theory of Gravity in Minkowski Space 闵科夫斯基空间引力理论
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700506
Naman Kumar
{"title":"A Theory of Gravity in Minkowski Space","authors":"Naman Kumar","doi":"10.1134/S0202289324700506","DOIUrl":"10.1134/S0202289324700506","url":null,"abstract":"<p>We propose a theory of gravity in Minkowski space. The basic idea is that the presence of mass affects the world line of particles in flat Minkowski background. Although General Relativity is in complete agreement with observations so far, the theory discussed in this paper can solve some of the conceptual difficulties of GR, such as the energy problem, that is at the core of constructing this theory. We also discuss the cosmic expansion of the present universe and comment on the early universe. Furthermore, we demonstrate how the flatness problem and horizon problem are solved within this framework. As it will become clear, this is a theory of principle and not a theory of construction.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"64 - 70"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529928","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
Projective Collineation in Space-Times of Pseudo-Symmetric Type
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700452
Uday Chand De, Krishnendu De
{"title":"Projective Collineation in Space-Times of Pseudo-Symmetric Type","authors":"Uday Chand De,&nbsp;Krishnendu De","doi":"10.1134/S0202289324700452","DOIUrl":"10.1134/S0202289324700452","url":null,"abstract":"<p>This article deals with an investigation of projective collineations in pseudo-symmetric type space-times. First we deduce that if a pseudo-Ricci symmetric space-time admits a projective collineation whose associated vector field is a special projective vector field, then the space-time represents a stiff matter fluid. Also, we establish that if a pseudo-projective symmetric space-time admits a projective collineation whose associated vector field is a projective vector field, then the space-time becomes an Einstein space-time. Finally, we illustrate that if a pseudo-projective symmetric space-time admits a non-affine projective vector field, then the space-time becomes a perfect fluid space-time.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"22 - 27"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530029","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
Existence of a Local Classical Solution to the Einstein-Scalar System in Higher Dimensions
IF 1.2 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2025-03-02 DOI: 10.1134/S0202289324700440
Mirda Prisma Wijayanto, Fiki Taufik Akbar, Bobby Eka Gunara
{"title":"Existence of a Local Classical Solution to the Einstein-Scalar System in Higher Dimensions","authors":"Mirda Prisma Wijayanto,&nbsp;Fiki Taufik Akbar,&nbsp;Bobby Eka Gunara","doi":"10.1134/S0202289324700440","DOIUrl":"10.1134/S0202289324700440","url":null,"abstract":"<p>We study the existence of a local classical solution to the Einstein-Scalar equations in higher dimensions. We reduce the problem to a single first-order integro-differential equation. Then, we employ the contraction mapping in the appropriate Banach space. Using the Banach fixed theorem, we show that there exists a unique fixed point, which is the solution to the main problem. Finally, for given initial data, we prove the existence of a local classical solution.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"31 1","pages":"13 - 21"},"PeriodicalIF":1.2,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530028","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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