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In an arbitrary axisymmetric stationary spacetime, we determine the expression for the tangential velocity of test objects following a circular stable geodesic motion in the equatorial plane, as function of the metric coefficients. Next, we…

Astrophysics · Physics 2007-05-23 Tonatiuh Matos , Dario Nunez , F. Siddhartha Guzman , Erandy Ramirez

This paper presents the study of dark-energy compact stars in the context of modified Rastall teleparallel gravity. It is the first time that dark energy celestial phenomena have been explored in this modified gravitational theory.…

General Relativity and Quantum Cosmology · Physics 2025-07-03 Allah Ditta , Xia Tiecheng , G. Mustafa , Değer Sofuoğlu , Asif Mahmood

Dynamical models of prototype gravastars made of anisotropic dark energy are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\gamma)\sigma$ divides the whole spacetime into two…

General Relativity and Quantum Cosmology · Physics 2011-07-21 R. Chan , M. F. A. da Silva , P. Rocha

Tidal effects related to the traversability across thin shells are examined in spherically symmetric geometries. We focus mainly on shells separating inner from outer regions of gravastars (de Sitter -- i.e. $\Lambda>0$ -- interior and…

General Relativity and Quantum Cosmology · Physics 2025-03-17 Cecilia Tomasini , Claudio Simeone , Emilio Rubín de Celis

In this article, we construct a broad family of spacetimes with spherically symmetric thin shells in unimodular gravity. We present the framework for the analysis of the dynamical stability of the configurations under perturbations…

General Relativity and Quantum Cosmology · Physics 2025-06-11 Gabriel R. Bengochea , Ernesto F. Eiroa , Griselda Figueroa-Aguirre

The physical properties of a (3+1)-D gravastar in the context of massive gravity are discussed in this work. In present investigation, the field equations have been solved for a static, uncharged sphere in order to achieve the gravastar…

General Relativity and Quantum Cosmology · Physics 2024-04-10 Piyali Bhar

This thesis investigates compact astrophysical objects within modified theories of gravity, focusing on neutron stars and strange stars. The work studies their internal structure, equilibrium, and stability in gravitational frameworks based…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Sneha Pradhan

This is a continuation and generalization of our earlier work on {\it gravastar} in (2+1) anti-de Sitter space-time to 2+1 dimensional solution of charged gravastar. Morphologically this gravastar contains three regions namely: (i) charged…

General Physics · Physics 2015-06-05 Farook Rahaman , A. A. Usmani , Saibal Ray , Safiqul Islam

This study explores the application of complexity factor within the context of Rastall gravity, exploring its implications on a static spacetime admitting spherical symmetry associated with anisotropic fluids under an electromagnetic field.…

General Relativity and Quantum Cosmology · Physics 2025-08-20 Tayyab Naseer

In this work we examine the internal structure of compact stars within an extended gravitational framework described by the function $f(\mathcal{R},\mathcal{G},\mathcal{T})$. Throughout this work, the quantity $\mathcal{R}$ refers to the…

General Relativity and Quantum Cosmology · Physics 2025-11-25 G. G. L. Nashed

In this work, we study the existence of strange star in the background of $f(\mathbb{T},\mathcal{T})$ gravity in the Einstein spacetime geometry, where $\mathbb{T}$ is the torsion tensor and $\mathcal{T}$ is the trace of the energy-momentum…

General Relativity and Quantum Cosmology · Physics 2021-10-13 I. G. Salako , M. Khlopov , Saibal Ray , M. Z. Arouko , Pameli Saha , Ujjal Debnath

In this work, we investigate a nonlinear electrodynamics model within the framework of $f(R,T)$ gravity. We begin by outlining the general features of the theory and analyzing the event horizon under conditions ensuring its real and…

General Relativity and Quantum Cosmology · Physics 2025-09-05 A. A. Araújo Filho , N. Heidari , I. P. Lobo , V. B. Bezerra

We explore possible non-Gaussian features of primordial gravitational waves by constructing model-independent templates for nonlinearity parameters of tensor bispectrum. Our analysis is based on Effective Field Theory of inflation that…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-16 Abhishek Naskar , Supratik Pal

We introduce two classes of spherically symmetric spacetimes having a thin shell of matter, in non-quadratic F(R) theories of gravity with non-constant scalar curvature R. In the first, the thin shell joins an inner region with an outer…

General Relativity and Quantum Cosmology · Physics 2020-10-07 Ernesto F. Eiroa , Griselda Figueroa-Aguirre

We consider a gravitational model in which matter is non-minimally coupled to geometry, with the effective Lagrangian of the gravitational field being given by an arbitrary function of the Ricci scalar, the trace of the matter…

General Relativity and Quantum Cosmology · Physics 2024-11-18 Zahra Haghani , Tiberiu Harko , Francisco S. N. Lobo , Hamid Reza Sepangi , Shahab Shahidi

The basic objective of this investigation is to explore the impact of a novel gravitational modification, specifically, the $f(\mathcal{G}, \mathbf{T}^2)$ (where $\mathbf{T}^2 \equiv T_{\alpha\beta}T^{\alpha\beta}$, $T^{\alpha\beta}$…

General Relativity and Quantum Cosmology · Physics 2022-04-12 Z. Yousaf , M. Z. Bhatti , S. Khan , P. K. Sahoo

We develop an extremely general and robust framework that can be adapted to wide classes of generic spherically symmetric thin-shell gravastars. The thin shell (transition layer) will be permitted to move freely in the bulk spacetimes,…

General Relativity and Quantum Cosmology · Physics 2015-12-25 Francisco S. N. Lobo , Prado Martín-Moruno , Nadiezhda Montelongo-García , Matt Visser

This research paper investigates the impact of non-metricity and matter source on the geometry of charged spheres in the presence of anisotropic matter configuration. We use a specific model of extended symmetric teleparallel theory to…

General Relativity and Quantum Cosmology · Physics 2024-12-03 M. Zeeshan Gul , Faisal Javed , M. Sharif , Shalan Alkarni

We consider a gravastar model made of anisotropic dark energy with an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\gamma)\sigma$ with an external de Sitter-Schwarzschild region. It is found that in…

General Relativity and Quantum Cosmology · Physics 2015-03-17 C. F. C. Brandt , R. Chan , M. F. A. da Silva , P. Rocha

This article introduces a nonstatic Reissner-Nordstr\"om metric, a metric that does not emit electromagnetic waves but can emit gravitational waves. We first use the GR theory to study a charged spherically symmetric gravitational source…

General Relativity and Quantum Cosmology · Physics 2025-04-08 Pham Van Ky