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London-Like Tensor Modes of Gravitational Waves in Cosmic String Cosmology 宇宙弦宇宙学中引力波的类伦敦张量模
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040035
Claudio Aravena-Plaza, Víctor Muñoz, Felipe A. Asenjo
{"title":"London-Like Tensor Modes of Gravitational Waves in Cosmic String Cosmology","authors":"Claudio Aravena-Plaza,&nbsp;Víctor Muñoz,&nbsp;Felipe A. Asenjo","doi":"10.1134/S0202289323040035","DOIUrl":"10.1134/S0202289323040035","url":null,"abstract":"<p>From a classical analysis, we show that gravitational waves in a cosmological medium with the equation of state parameter <span>(w=-1/3)</span> can follow a London-like equation, implying that some gravitational wave solutions present a decay for certain wavelengths. This scenario, corresponding to a cosmic string cosmology, induces an attenuation temporal scale on the gravitational wave propagation. We discuss on how these solutions impose a limit on the wavelength of the waves that can propagate, which depends on the type of spatial curvature and the energy density content of this type of cosmology.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"400 - 403"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437131","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
Models of Anisotropic Stars in Spherically Symmetric Space-Time 球对称时空中各向异性恒星模型
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040126
Ankita Jangid, B. S. Ratanpal, K. K. Venkataratnam
{"title":"Models of Anisotropic Stars in Spherically Symmetric Space-Time","authors":"Ankita Jangid,&nbsp;B. S. Ratanpal,&nbsp;K. K. Venkataratnam","doi":"10.1134/S0202289323040126","DOIUrl":"10.1134/S0202289323040126","url":null,"abstract":"<p>We introduce a new, well-mannered and stable model. To create the model, we used well-known Finch–Skea [1] ansatz for the metric potential <span>(g_{rr})</span>. For our model, we look into a number of physical variables, including the energy density, pressures, mass, anisotropy factor, gravitational redshifts, energy conditions, and stability analysis by utilizing graphs. This made sure that our suggested solutions behave as expected and represent physically plausible models for anisotropic matter distributions. We consider compact stars to compare our model with observational data: SAX J1808.4-3658, Her X-1, 4U 1608-52, PSR B1913 <span>(+)</span> 16, Cen X-3, LMC X-4, PSR J1614-2230, 4U1538-52, PSR J1903 <span>(+)</span> 327, SMC X-1, 4U 1820-30, Vela X-1.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"479 - 485"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437134","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
Phantom Dark Energy Nature of String-Fluid Cosmological Models in (boldsymbol{f(Q)})-Gravity (boldsymbol{f(Q)}) -重力中弦流体宇宙学模型的幻影暗能量性质
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040151
Dinesh Chandra Maurya
{"title":"Phantom Dark Energy Nature of String-Fluid Cosmological Models in (boldsymbol{f(Q)})-Gravity","authors":"Dinesh Chandra Maurya","doi":"10.1134/S0202289323040151","DOIUrl":"10.1134/S0202289323040151","url":null,"abstract":"<p>The present investigation is focused on a curvatureless and torsionless modified nonmetricity theory of gravity in the context of string fluid. For that, we use an anisotropic, locally rotationally symmetric (LRS), Bianchi Type I space-time universe with the arbitrary function <span>(f(Q)=Q+Lambda)</span>, where <span>(Q)</span> is the nonmetricity scalar and <span>(Lambda)</span> is the cosmological constant. We solve the field equations using a time-dependent deceleration parameter and obtain various cosmological parameters. To obtain the best-fit values of the model parameters, we use the observational constraints on Hubble function <span>(H(z))</span> and the apparent magnitude <span>(m(z))</span> using the observational datasets <span>(H(z))</span> and SNe Ia. Using these values of model parameters, we investigate cosmological scenarios of the model. We observe the behavior of the variable dark energy equation of state (EoS) parameter <span>(omega)</span> in the context of a string fluid universe and find the present value of the effective EoS parameter <span>(omega^{textrm{eff}}&lt;-1)</span> that corresponds to phantom dark energy. Also, we analyze the statefinder parameters and estimate the present age of the universe.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"345 - 361"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437140","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
On Algebraic Dependence of Cosmological Parameters 论宇宙学参数的代数依赖性
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040163
Žarko Mijajlović, Danijela Branković
{"title":"On Algebraic Dependence of Cosmological Parameters","authors":"Žarko Mijajlović,&nbsp;Danijela Branković","doi":"10.1134/S0202289323040163","DOIUrl":"10.1134/S0202289323040163","url":null,"abstract":"<p>We consider the inverse function of the scale factor <span>(a(t))</span> of the Friedmann equations, discussing also the asymptotics of cosmological parameters under various assumptions on the <span>(Lambda)</span>CDM model. Using algebraic dependencies between the cosmological parameters and the representation of the inverse function of the scale factor <span>(a(t))</span> as an elliptic integral with a parameter, we compute in a uniform way some special events in the universe’s evolution.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"456 - 467"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437177","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: 1
The Fate of the Universe Evolution in the Quadratic Form of Ricci–Gauss–Bonnet Cosmology 里奇-高斯-邦尼特宇宙学二次型中宇宙演化的命运
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040138
Santosh V Lohakare, Francisco Tello-Ortiz, B. Mishra, S. K. Tripathy
{"title":"The Fate of the Universe Evolution in the Quadratic Form of Ricci–Gauss–Bonnet Cosmology","authors":"Santosh V Lohakare,&nbsp;Francisco Tello-Ortiz,&nbsp;B. Mishra,&nbsp;S. K. Tripathy","doi":"10.1134/S0202289323040138","DOIUrl":"10.1134/S0202289323040138","url":null,"abstract":"<p>We investigate the possibility of a future singularity due to accelerating expansion of the Universe in a gravitational theory that comprises the Ricci scalar <span>(R)</span> and the Gauss–Bonnet invariant <span>(mathcal{G})</span>, known as <span>(F(R,mathcal{G}))</span> gravity, which can be viewed in the quadratic form. Three models are presented using Hubble parameters to represent a finite and infinite future. The model parameters are analyzed on the basis of their physical and geometrical properties. This study also explores the properties of the modified gravitational theory, and neither a future singularity nor a little or pseudo-rip are posed as threats to the fate of the Universe. We present scalar perturbation approaches to perturbed evolution equations and demonstrate their stability.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"443 - 455"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437194","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: 2
Cosmological Model with Cosmic Transit Behavior in Brans-Dicke Theory Brans-Dicke理论中具有宇宙凌日行为的宇宙学模型
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040187
Sunil K. Tripathy, Alaka Priyadarsini Sendha, Sasmita Kumari Pradhan, Zashmir Naik, B. Mishra
{"title":"Cosmological Model with Cosmic Transit Behavior in Brans-Dicke Theory","authors":"Sunil K. Tripathy,&nbsp;Alaka Priyadarsini Sendha,&nbsp;Sasmita Kumari Pradhan,&nbsp;Zashmir Naik,&nbsp;B. Mishra","doi":"10.1134/S0202289323040187","DOIUrl":"10.1134/S0202289323040187","url":null,"abstract":"<p>We have constructed a dark energy cosmological model in the framework of the generalized Brans Dicke (GBD) theory with a self-interacting potential. The source of dark energy is considered through a unified dark fluid (UDF) characterized by a linear equation of state (EoS). A time-varying deceleration parameter simulating the cosmic transit behavior has been introduced to get the dynamical behavior of the model. The <span>(H(z))</span> data have been explored to constrain the model parameters and to study the dynamical aspects of the Brans-Dicke parameter and the scalar field.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"468 - 478"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437178","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 the Arrow of Time in Nonminimally Coupled Scalar Field FRW Cosmology 关于非最小耦合标量场FRW宇宙学中的时间箭头的注释
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040023
L. A. León Andonayre, M. A. Skugoreva, A. V. Toporensky, T. Vargas
{"title":"A Note on the Arrow of Time in Nonminimally Coupled Scalar Field FRW Cosmology","authors":"L. A. León Andonayre,&nbsp;M. A. Skugoreva,&nbsp;A. V. Toporensky,&nbsp;T. Vargas","doi":"10.1134/S0202289323040023","DOIUrl":"10.1134/S0202289323040023","url":null,"abstract":"<p>We revisit the cyclic Universe scenario in scalar field FRW cosmology and check its applicability for a nonminimally coupled scalar field. We show that for the most popular case of a quartic potential and the standard nonminimal coupling this scenario does work. On the other hand, we identify certain cases where the cyclic model fails to work and present the corresponding reasons for that.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"404 - 410"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437106","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
Quantization of Measure in Gravitation 引力测量的量子化
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040072
V. Dzhunushaliev, V. Folomeev
{"title":"Quantization of Measure in Gravitation","authors":"V. Dzhunushaliev,&nbsp;V. Folomeev","doi":"10.1134/S0202289323040072","DOIUrl":"10.1134/S0202289323040072","url":null,"abstract":"<p>Using the Radon–Nikodym theorem concerning the relation between any two measures, as well as the methods employed in loop quantum gravity, it is shown that in gravitation one can quantize any measure which is not even associated with metric. We have considered the simplest case where the proportionality coefficient between two operators of measure (the Radon–Nikodym derivative) is some function. The result is that in the right-hand side of the commutation relations for the measure the fundamental length becomes a variable quantity, and this can lead to smoothing the singularity. The case where the Radon–Nikodym derivative is an operator is also under discussion. Classical and quantum theories in the background of space endowed with quantum measure are under consideration.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"367 - 373"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437129","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: 1
Thick Fluid Disks Around Binary Black Holes 双黑洞周围的厚流体盘
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-11-23 DOI: 10.1134/S0202289323040060
S. V. Chernov
{"title":"Thick Fluid Disks Around Binary Black Holes","authors":"S. V. Chernov","doi":"10.1134/S0202289323040060","DOIUrl":"10.1134/S0202289323040060","url":null,"abstract":"<p>A model of a thick fluid disk around a binary black hole is considered. A binary black hole is described by the Majumdar-Papapetrou solution. The hydrodynamic equations in this metric are written out. Exact analytical solutions are presented. A generalization to the case of a toroidal magnetic field is carried out.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 4","pages":"437 - 442"},"PeriodicalIF":0.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437130","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
Tsallis Holographic Dark Energy in Bianchi Type I Universe in the Framework of (boldsymbol{f(R)}) Theory of Gravity 在(boldsymbol{f(R)})重力理论框架下Bianchi I型宇宙中的Tsallis全息暗能量
IF 0.9 4区 物理与天体物理
Gravitation and Cosmology Pub Date : 2023-09-04 DOI: 10.1134/S0202289323030118
Chandra Rekha Mahanta, Krishna Pandit, Manash Pratim Das
{"title":"Tsallis Holographic Dark Energy in Bianchi Type I Universe in the Framework of (boldsymbol{f(R)}) Theory of Gravity","authors":"Chandra Rekha Mahanta,&nbsp;Krishna Pandit,&nbsp;Manash Pratim Das","doi":"10.1134/S0202289323030118","DOIUrl":"10.1134/S0202289323030118","url":null,"abstract":"<p>We consider a Bianchi Type I universe filled with cold dark matter and non-interacting Tsallis holographic dark energy in the framework of <span>(f(R))</span> theory of gravity. We take the GO scale as an IR cutoff and find exact solutions of the field equations by considering a linearly varying deceleration parameter. The evolution of different cosmologically relevant parameters are studied graphically, and Statefinder diagnostics is performed in the light of recent cosmological observations. We find that our model corresponds to current accelerated expansion scenarios, and the function <span>(f(R)approx R)</span> implies that our model resembles General Relativity.</p>","PeriodicalId":583,"journal":{"name":"Gravitation and Cosmology","volume":"29 3","pages":"305 - 314"},"PeriodicalIF":0.9,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4193658","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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