Thermodynamic implications of Brans–Dicke cosmologies

Singh, Ashutosh

doi:10.1140/epjp/s13360-021-01519-4

Cited by 24 publications

(5 citation statements)

References 54 publications

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“…We conclude with a few remarks: (i) In the present work, the equations for the geodesic in spherically symmetric space-time obtained by Nolan [8] have been completely solved. This will lead to a better understanding of the physical situation regarding singularities inside spherically symmetric black holes [9][10][11][12][13][14][15], in the realm of astrophysics [16][17][18][19] as well as cosmology [20][21][22][23][24].…”

Section: Discussionmentioning

confidence: 99%

Exact solution to the geodesic equations in spherically symmetric space-time

Dhara¹,

Ghosh²,

Ray

et al. 2022

Preprint

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The strength of a singularity in spherical symmetry can be described by covariant equations. This was generated by Nolan [Phys. Rev. 60, 024014 (1999)] and some models have been examined him also. It draws a distinction between singularities, i.e. which are central and which are not. Nolan derived the necessary conditions [Phys. Rev. D 62, 044015 (2000)] for the singularity to be gravitationally weak. From these conditions certain conclusions may be drawn about the nature of the singularity without having to integrate the geodesic equations. In the present letter, the equations for the geodesic in spherically symmetric space-time obtained by Nolan are completely solved. This will lead to a better understanding of the physical situation regarding singularity.

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Section: Discussionmentioning

confidence: 99%

Exact solution to the geodesic equations in spherically symmetric space-time

Dhara¹,

Ghosh²,

Ray

et al. 2022

Preprint

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show abstract

“…The de Sitter, accelerating power-law expansion can be achieved for q = −1 and −1 < q < 0 respectively. For q < −1, super-exponential expansion scenario exists [45][46][47][48][49]. It have been confirmed by observational results that the universe is currently expanding with acceleration and it has been decelerating in the past [50].…”

Section: Cosmological Equationsmentioning

confidence: 93%

Qualitative study of anisotropic Rastall cosmologies

Singh,

Pradhan

2022

Preprint

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We perform dynamical analysis of anisotropic Rastall cosmologies and, in particular Kantowski-Sachs, locally rotationally symmetric (LRS) Bianchi I and LRS Bianchi III cosmologies. Using dynamical system techniques, a qualitative analysis of cosmological equations yield physically interesting cases which are in agreement with observations such as de Sitter, accelerating, stable attractors are isotropic. Features such as isotropization and cosmological bounce are discussed in detail.

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“…With this notation, dN = Hdt. The dynamical variables (7) are suitable for study of the expanding cosmologies but these will not be well-defined variables in the bouncing models [63][64][65][66]. Since, in the bouncing models, H = 0 at the bounce.…”

Section: The Autonomous System and The Corresponding Universe Evolutionmentioning

confidence: 99%

Lyra cosmologies with the dynamical system perspective

Singh

2024

Phys. Scr.

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In this study, we revisit the homogeneous and isotropic, spatially curved model in the Lyra geometry framework. We apply the dynamical system approach to study the universe evolution in model. The present cosmic dynamical system formulation is independent of the model parameter which yields the universe expansion phases dominated by the stiff fluid, radiation, dark matter and dark energy. These expansion phases in the Lyra model are consistent with the General relativity model. In addition, the displacement vector field of the Lyra geometry model will give rise to the stiff matter dominated phase during early times of the universe evolution. The cosmographic parameters, EoS parameter and statefinder diagnostic have been utilized in the dynamical system to illustrate the cosmic evolution of the universe. The numerical solution technique is used to illustrate graphical behaviors of the cosmological parameters. On the basis of dynamical system and numerical analysis, we exhibit that the model explains accelerating universe expansion with transition from the decelerating phase and it will lead to the $\Lambda$ cold dark matter ($\Lambda$CDM) model in the near future.

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Thermodynamic implications of Brans–Dicke cosmologies

Cited by 24 publications

References 54 publications

Exact solution to the geodesic equations in spherically symmetric space-time

Exact solution to the geodesic equations in spherically symmetric space-time

Qualitative study of anisotropic Rastall cosmologies

Lyra cosmologies with the dynamical system perspective

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