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We investigate the cosmology of a class of model with noncanonical scalar field and matter both in FRW closed and open background. Writing the Einstein Equations in terms of dimensionless dynamical variables suitable for studying bouncing…

General Relativity and Quantum Cosmology · Physics 2015-01-12 Manabendra Sharma

Within a semiclassical framework, we investigate spherically symmetric solutions of the Einstein equations that (i) develop a trapped region within a finite time as measured by distant observers, and (ii) remain sufficiently regular at the…

General Relativity and Quantum Cosmology · Physics 2025-09-16 Swayamsiddha Maharana , Rama Vadapalli

We have considered an action of the form $T+f(T)+L_m$ describing Einstein's gravity plus a function of the torsion scalar. By considering an exact power-law solution we have obtained the Friedmann equation as a differential equation for the…

General Physics · Physics 2015-05-30 M. R. Setare , F. Darabi

In this paper, we have emphasized the stability analysis of the accelerating cosmological models obtained in $f(T)$ gravity theory. The behavior of the models based on the evolution of the equation of state parameter shows phantom-like…

General Relativity and Quantum Cosmology · Physics 2022-05-25 L. K. Duchaniya , Santosh V Lohakare , B. Mishra , S. K. Tripathy

We discuss modified teleparallel gravity with function $f(T,T_G)$ in the action, where function depend on two arguments: torsion scalar $T$ and analogue of Gauss-Bonnet invariant $T_G$. In contradistinction to usual teleparallel gravity…

General Relativity and Quantum Cosmology · Physics 2016-05-02 Petr V. Tretyakov

In the present investigation compact stellar models are dealt with in the framework of the modified gravity theory, specifically of $f(\mathbb{T},\mathcal{T})$ type. We have considered that the compact objects are following a spherically…

General Relativity and Quantum Cosmology · Physics 2021-06-29 Ines G. Salako , Chayan Ranjit , M. Khlopov , Saibal Ray , Utpal Mukhopadhyay

We derive here the metric for Einstein's static universe (ESU) directly from Einstein equation, i.e., by considering both $G_{ik}$ and $T_{ik}$. We find that in order that the fluid pressure and acceleration are {\em uniform} and finite…

General Physics · Physics 2008-08-19 Abhas Mitra

Compact stars have long served as a test bed of gravitational models and their coupling with stellar matter. In this work, we explore the behavior of an exponential model in f(T) gravity through the Tolman-Oppenheimer-Volkoff equation. This…

General Relativity and Quantum Cosmology · Physics 2024-12-30 Gabriel Farrugia , Carlos Gafa' , Jackson Levi Said

Off-diagonal vacuum and nonvacuum configurations in Einstein gravity can mimic physical effects of modified gravitational theories of $f(R,T,R_{\mu \nu}T^{\mu \nu})$ type. To prove this statement, exact and approximate solutions are…

General Relativity and Quantum Cosmology · Physics 2015-07-01 Emilio Elizalde , Sergiu I. Vacaru

Static spherically symmetric (SSS) solutions of f(R) gravity are studied in the Einstein frame. The solutions involve SSS configuration mass M and scalaron mass $\mu$ (in geometrized units); for typical astrophysical masses, the…

General Relativity and Quantum Cosmology · Physics 2025-07-28 V. I. Zhdanov

The spacetime singularities play a useful role in gravitational theories by distinguishing physical solutions from non-physical ones. The problem, we studying in this paper is: are these singularities stable? To answer this question, we…

High Energy Physics - Theory · Physics 2015-06-26 Peter K. Silaev , Slava G. Turyshev

A $(m+ 3)$-dimensional Einstein-Gauss-Bonnet gravitational model including the Gauss-Bonnet term and the cosmological term $\Lambda$ is considered. Exact solutions with exponential time dependence of two scale factors, governed by two…

General Relativity and Quantum Cosmology · Physics 2020-11-16 V. D. Ivashchuk , A. A. Kobtsev

In recent few years, the Gauss-Bonnet $f(\mathcal{G},\mathrm{\textit{T}})$ theory of gravity has fascinated considerable researchers owing to its coupling of trace of the stress-energy tensor $T$ with the Gauss-Bonnet term $\mathcal{G}$. In…

General Relativity and Quantum Cosmology · Physics 2023-04-14 Mushtaq Ahmad , M. Farasat Shamir , G. Mustafa

We analyze the stability of the Einstein static universe in scalar-tensor theory of gravity, and find it can be stable against both scalar and tensor perturbations under certain conditions. By assuming the emergent scenario originating from…

General Relativity and Quantum Cosmology · Physics 2023-06-13 Qihong Huang , He Huang , Bing Xu

We study the stability under linear perturbations of a class of static solutions of Einstein-Gauss-Bonnet gravity in $D=n+2$ dimensions with spatial slices of the form $\Sigma_{\k}^n \times {\mathbb R}^+$, $\Sigma_{\k}^n$ an $n-$manifold of…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Gustavo Dotti , Reinaldo J. Gleiser

Modeling of matter bounce in $f(R,T)$ gravity has been presented with no violation of the null energy condition. Only a closed universe with negative pressure is allowed in good agreement with some recent observations which favor a universe…

General Relativity and Quantum Cosmology · Physics 2022-06-22 Vinod Kumar Bhardwaj , Anirudh Pradhan , Nasr Ahmed , A. A. Shaker

The present work analyzes the various conditions in which there can be a bouncing universe solution in f(R) gravity. In the article an interesting method, to analyze the bouncing FRW solutions in a spatially flat universe using f(R) gravity…

General Relativity and Quantum Cosmology · Physics 2014-12-09 Niladri Paul , Saikat Nil Chakrabarty , Kaushik Bhattacharya

We obtain an approximate global stationary and axisymmetric solution of Einstein's equations which can be thought as a simple two layers star model: a self-gravitating ball built up by two layers of perfect fluid having different linear…

General Relativity and Quantum Cosmology · Physics 2018-06-12 Alfred Molina , Eduardo Ruiz

A new set of field equations for a space-time dependent Newton's constant $G(x)$ and cosmological constant $\Lambda(x)$ in the presence of matter is presented. We prove that it represents the most general mathematically consistent,…

General Relativity and Quantum Cosmology · Physics 2021-05-19 Alfio Bonanno , Georgios Kofinas , Vasilios Zarikas

The basic aim of this manuscript is to investigate the cosmological solutions in the context of the modified $f(R, T)$ theory of gravity, where $R$ is the Ricci scalar and $T$ is the trace of the energy-momentum tensor. For our current…

General Relativity and Quantum Cosmology · Physics 2024-03-26 Adnan Malik , Tayyaba Naz , Aimen Rauf , M. Farasat Shamir , Z. Yousaf
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