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A scalar--tensor theory of gravity, containing an arbitrary coupling function $F(\phi)$ and a general potential $V(\phi)$, is considered in the context of a spatially flat FLRW model. The use of reparametrization invariance enables a…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Petros A. Terzis , N. Dimakis , T. Christodoulakis

f(R)-gravity with geometric torsion (not related to any spin fluid) is considered in a cosmological context. We derive the field equations in vacuum and in presence of perfect-fluid matter and discuss the related cosmological models.…

General Relativity and Quantum Cosmology · Physics 2009-01-21 S. Capozziello , R. Cianci , C. Stornaiolo , S. Vignolo

This paper deals with the collapse and expansion of relativistic anisotropic self-gravitating source. The field equations for non-radiating and non-static plane symmetric anisotropic source have been evaluated. The non-radiating property of…

General Relativity and Quantum Cosmology · Physics 2014-03-11 G. Abbas

In this paper, we adopt minimal gravitational decoupling scheme to extend a non-static spherically symmetric isotropic composition to anisotropic interior in…

General Relativity and Quantum Cosmology · Physics 2023-08-03 M. Sharif , Tayyab Naseer

Anisotropic spherically symmetric solutions within the framework of the Brans-Dicke theory are uncovered through a unique gravitational decoupling approach involving a minimal geometric transformation. This transformation effectively…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Kazuharu Bamba , M. Z. Bhatti , Z. Yousaf , Z. Shoukat

In this paper, we explore the existence of various non-singular compact stellar solutions influenced by the Maxwell field within the matter-geometry coupling based modified gravity. We start this analysis by considering a static spherically…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Tayyab Naseer , Jackson Levi Said

In this article, we propose a physical condition to extend interior isotropic solutions to anisotropic domains by gravitational decoupling in the framework of the Minimal Geometric Deformation approach. In particular, it is found that by…

General Relativity and Quantum Cosmology · Physics 2020-03-24 Gabriel Abellán , Angel Rincon , Ernesto Fuenmayor , Ernesto Contreras

In this work, we introduce the {\it complexity factor} in the context of self--gravitating fluid distributions for the case of black holes by employing the Newman-Penrose formalism. In particular, by working with spherically symmetric and…

General Relativity and Quantum Cosmology · Physics 2022-09-21 P. Bargueño , E. Fuenmayor , E. Contreras

We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this…

General Relativity and Quantum Cosmology · Physics 2018-02-28 S. K. Maurya , Ayan Banerjee , Sudan Hansraj

In this study we explore the astrophysical implications of pressure anisotropy on the physical characteristics of millisecond pulsars within the framework of $f(Q)$ gravity, {in particular $f(Q)=-\alpha\, Q - \beta$, where $\alpha$ and…

General Relativity and Quantum Cosmology · Physics 2024-10-08 S. K. Maurya , Ksh. Newton Singh , G. Mustafa , M. Govender , Abdelghani Errehymy , Abdul Aziz

We analyze the evolution of a Friedmann-Robertson-Walker spacetime within the framework of $f(R)$ metric gravity using an exponential model. We show that $f(R)$ gravity may lead to a vanishing effective cosmological constant in the far…

General Relativity and Quantum Cosmology · Physics 2018-10-31 Luisa G. Jaime , Marcelo Salgado

We show that the inclusion of simple anisotropic pressures stops the isotropic Friedmann universe being a stable attractor as an initial or final singularity is approached when pressures can exceed the energy density. This shows that the…

General Relativity and Quantum Cosmology · Physics 2014-11-20 John D Barrow , Kei Yamamoto

In this work, we develop a new relativistic model for a charged anisotropic compact star in the framework of modified symmetric teleparallel gravity, namely $f(Q)$-Euler-Heisenberg gravity. By employing the MIT bag model equation of state,…

General Relativity and Quantum Cosmology · Physics 2025-12-03 Allah Ditta , M. Yousaf , G. Mustafa , S. K. Maurya , Farruh Atamurotov , Orhan Donmez , Sardor Murodov

A generalized model of space-time is given, taking into consideration the anisotropic structure of fields which are depended on the position and the direction (velocity).In this framework a generalized FRW-metric the Raychaudhouri and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 P. C. Stavrinos , A. P. Kouretsis , M. Stathakopoulos

This paper investigates the behavior of anisotropic static spheres that are constructed by employing a minimal geometric deformation in the framework of $f(R,T^{2})$ gravity ($T^{2}=T_{\zeta\nu}T^{\zeta\nu}$, $R$ is the Ricci scalar and…

General Relativity and Quantum Cosmology · Physics 2022-07-13 M. Sharif , Shazmeena Iltaf

Motivated by conventional gauge theories, we consider a theory of gravity in which the Einstein-Hilbert action is replaced by a term that is quadratic in the Riemann tensor. We focus on cosmological solutions to the field equations in flat,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. N. Lasenby , C. J. L. Doran , R. Heineke

We study $f(R)$ gravity models in the language of scalar-tensor theories. The correspondence between $f(R)$ gravity and scalar-tensor theories is revisited since $f(R)$ gravity is a subclass of Brans-Dicke models, with a vanishing coupling…

General Relativity and Quantum Cosmology · Physics 2017-06-28 Joseph Ntahompagaze , Amare Abebe , Manasse Mbonye

This paper is the first in a sequence of three devoted to the formulation of a theory of self-gravitating anisotropic fluids in both Newtonian and relativistic gravity. In this first paper we set the stage, place our work in the context of…

General Relativity and Quantum Cosmology · Physics 2024-06-06 Tom Cadogan , Eric Poisson

This paper investigates realistic anisotropic matter configurations for spherical symmetry in the framework of $f(R)$ gravity. The solutions obtained from Buchdahl-I metric are used to determine the behavior of PSR J0740+6620, PSR…

General Relativity and Quantum Cosmology · Physics 2025-02-24 A. Zahra , S. A. Mardan , Muhammad Bilal Riaz , S. Saleem

Mathematical modeling within the framework of the general theory of relativity has been used to explain the behavior and structure of massive objects as neutron stars, quasars, black holes, pulsars and white dwarfs and requires finding the…

General Relativity and Quantum Cosmology · Physics 2023-10-04 Manuel Malaver , Maria Esculpi
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