An axially symmetric transitioning models with observational constraints

Bhardwaj, Vinod Kumar; Dixit, Archana; Rani, Rita; Goswami, G. K.; Pradhan, Anirudh

doi:10.1016/j.cjph.2022.09.007

Cited by 17 publications

(6 citation statements)

References 103 publications

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“…However, regarding this possibility a counter argument is that the fine‐tuned Λ is required for the regime under consideration. [ 50,51 ] But till date there is no proof that this is guaranteed by any dynamics, or protected against quantum corrections and so to obtain a feasible solution to the cosmological constant problem is a remote possibility only.…”

Section: Discussionmentioning

confidence: 99%

A study of McVittie Spacetime in Stationary and Dynamical Regime

Bhattacharyya¹,

Ray

Khlopov

et al. 2022

Fortschritte der Physik

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One of the solutions of the Einstein equations, called McVittie solution, signifying a black hole embedded by the dynamic spacetime is studied. In the stationary spacetime the Mcvittie metric becomes the Schwarzschild-de Sitter metric (SdS). The geodesic of a freely falling test particle towards the black hole is examined in the SdS spacetime. It is found that unlike the Schwarzschild case the potential of such particle becomes maximum at a point where it eventually stops for a while and then resumes its motion towards the center of the black hole. It is shown that an observer or system of particles is spaghettified near the black hole singularity in the SdS spacetime. The dynamics of the universe in the framework of McVittie metric, being a generalized time dependent SdS solution, is represented in terms of that point, called stationary or turning point. The motion of the stationary point is studied in various regimes of the expanding universe and the possible outcomes are discussed in brief.

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Section: Discussionmentioning

confidence: 99%

A study of McVittie Spacetime in Stationary and Dynamical Regime

Bhattacharyya¹,

Ray

Khlopov

et al. 2022

Fortschritte der Physik

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“…Firstly, a gravitational equation is expressed in terms of the e-folding number N. From there, simplifying the resulting second-order differential equation allows us to deduce the value of f (R, 𝒢). Now, since the e-folding number is defined as N = ln(a∕a 0 ), therefore, from Equations ( 6), (7), the Ricci scalar R and the Gauss-Bonnet invariant 𝒢 can be written as…”

Section: Formalism Of Function F (R 𝒢)mentioning

confidence: 99%

“…In the literature, there are many models in which deceleration in early time and acceleration expansion in late time are shown. [1][2][3][4][5][6][7] In the theory of cosmology, dark energy is discussed with many types of assumptions. A huge amount of work has been done on dark energy models.…”

Section: Introductionmentioning

confidence: 99%

Bouncing Cosmology in f(R,G)$f(R,\mathcal {G})$ Gravity with Thermodynamic Analysis

Shaily,

Singh,

Singh

2024

Fortschritte der Physik

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The evolution of the universe in a modified gravity theory that includes the terms Ricci scalar () and the Gauss‐Bonnet invariant () is studied. The function is obtained using the e‐folding number and reconstruction technique by assuming an appropriate parameterization of the scale factor . In this model, the various cosmological parameters are analyzed to explicate the bouncing scenario of the universe with the help of the contraction and expansion phases of the universe before and after the bouncing point of the model, respectively. A violation of the null energy condition is found. Additionally, the ghost condensate nature of the model in the neighborhood of the bouncing point () is seen. Furthermore, the deceleration parameter is not defined at the bouncing point, i.e., at and approaches a finite value in later times (). Finally, the evolution of the Hawking temperature and the validity of the second law of thermodynamics in the bouncing scenario of our model are discussed.

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“…We analyze the cosmological perturbation to study the evolution of the universe from the Big Bang. Several authors have worked on perturbation analysis for a homogeneous background cosmology [76][77][78][79][80][81]. It is believed that due to a tiny perturbation in energy density, the cosmic fluid is not stable.…”

Section: Stability Of the Modelmentioning

confidence: 99%

GATT: A Genetic Algorithm-based Tool for Automating Timetable Scheduling at Netaji Subhas University of Technology

Singh

Sibal

Tyagi

2021

2021 Thirteenth International Conference on Contemporary Computing (IC3-2021)

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We investigate a bounce realization in the framework of higher order curvature in f (R, T ) modified theory of gravity. We perform a detailed analysis of the cosmological parameters to explain the contraction phase, the bounce phase, and the expansion phase. Furthermore, we observe a violation of the null energy condition, instability of the model, and a singularity upon deceleration at the bouncing point, which are the supporting results for a bouncing cosmology. The outcome of the slow roll parameters is satisfactory to understand the inflation era and the equation of state parameter exhibits a ghost condensate behavior of the model near the bounce. Additionally, we discuss the stability of the model using linear perturbations in the Hubble parameter as well as the energy density.

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An axially symmetric transitioning models with observational constraints

Cited by 17 publications

References 103 publications

A study of McVittie Spacetime in Stationary and Dynamical Regime

A study of McVittie Spacetime in Stationary and Dynamical Regime

Bouncing Cosmology in f(R,G)$f(R,\mathcal {G})$ Gravity with Thermodynamic Analysis

GATT: A Genetic Algorithm-based Tool for Automating Timetable Scheduling at Netaji Subhas University of Technology

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