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In this paper, we investigate the thermodynamic behavior of a horizonless compact object within the framework of Rastall-Rainbow (RR) gravity. Working with local shell thermodynamics for gravastar and an exterior fiducial temperature, we…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Sareh Eslamzadeh , Saheb Soroushfar

The thermodynamics of black holes provides a profound link between gravity, quantum theory and statistical mechanics. It serves as a useful tool for testing theories beyond Einstein's gravity. In this work of ours, we investigate the newly…

High Energy Physics - Theory · Physics 2026-02-16 Amijit Bhattacharjee , Prabwal Phukon

We study static traversable wormholes obtained by Morris and Thorne in general relativity (GR) in the framework of a modified theory of gravity. The modified gravitational action $f(R,T)$ is a function of the Ricci scalar ($R$) and of the…

General Relativity and Quantum Cosmology · Physics 2021-08-25 A Chanda , S Dey , B C Paul

Within the metric formalism of $f(R)$ theories of gravity, where $R$ is the Ricci scalar, we study the hydrostatic equilibrium structure of compact stars with the inclusion of anisotropic pressure. In particular, we focus on the $f(R)=…

General Relativity and Quantum Cosmology · Physics 2022-07-11 Juan M. Z. Pretel , Sergio B. Duarte

Alternative gravity theory is currently an incredibly significant technique for addressing some enduring experimental difficulties, such as the universe's dark region. They may also be employed in celestial cosmology, producing results that…

General Relativity and Quantum Cosmology · Physics 2024-05-01 Tayyaba Naz , Adnan Malik , Zenab Ramay

In this article, we consider a conventional black hole under f(R) gravity. Due to the small fluctuations around the equilibrium state, we have summarized the expression of the modified thermodynamic entropy of this black hole. At the same…

General Relativity and Quantum Cosmology · Physics 2022-01-27 Wen-Xiang Chen , Yao-Guang Zheng , Jing-Yi Zhang

We investigate a coupled system consisting of a complex scalar field, a U(1) gauge field, a complex Higgs scalar field, and Einstein gravity. We present nontopological soliton star solutions in which the interior geometry is described by…

High Energy Physics - Theory · Physics 2024-09-25 Tatsuya Ogawa , Hideki Ishihara

We present a stationary spherically symmetric solution of the Einstein equations, with a source generated by a scalar field of $q$-theory. In this theory Riemannian gravity, as described by the Einstein - Hilbert action, is coupled to a…

General Relativity and Quantum Cosmology · Physics 2023-07-26 M. Selch , J. Miller , M. A. Zubkov

The ergoregion instability is known to affect very compact objects that rotate very rapidly and do not possess a horizon. We present here a detailed analysis on the relevance of the ergoregion instability for the viability of gravastars.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Cecilia B. M. H. Chirenti , Luciano Rezzolla

We consider a $f(R)$ gravity theory in $(2+1)$-dimensions with a self-interacting scalar field non-minimally coupled to gravity. Without specifying the form of the $f(R)$ function, solving the field equations we find that the Ricci scalar…

General Relativity and Quantum Cosmology · Physics 2022-02-18 Thanasis Karakasis , Eleftherios Papantonopoulos , Zi-Yu Tang , Bin Wang

This research work provides an exhaustive investigation of the viability of different coupled wormhole (WH) geometries with the relativistic matter configurations in the $f(R,G,T)$ extended gravity framework. We consider a specific model in…

General Relativity and Quantum Cosmology · Physics 2025-04-01 M. Ilyas , A. R. Athar , Fawad Khan , Nasreen Ghafoor , Haifa I. Alrebdi , Kottakkaran Sooppy Nisar , Abdel-Haleem Abdel-Aty

We study relativistic stars in the context of scalar tensor theories of gravity that try to account for the observed cosmic acceleration and satisfy the local gravity constraints via the chameleon mechanism. More specifically, we consider…

General Relativity and Quantum Cosmology · Physics 2015-03-13 E. Babichev , D. Langlois

In this paper, we consider three types (static, static charged and rotating charged) of black holes in f(R) gravity. We study the thermodynamical behavior, stability conditions and phase transition of these black holes. It will be shown…

General Relativity and Quantum Cosmology · Physics 2016-08-30 Saheb Soroushfar , Reza Saffari , Negin Kamvar

This article explores wormhole solutions within the framework of Finsler geometry and the modified gravity theory. Modifications in gravitational theories, such as $f(\mathcal{R}, \mathcal{T})$ gravity, propose alternatives that potentially…

General Relativity and Quantum Cosmology · Physics 2024-07-11 Yashwanth B. R. , Narasimhamurthy S. K. , Z. Nekouee

In this article, we explore the RN black hole under f(R) gravity and its thermodynamic properties. We begin by examining the small fluctuations around the equilibrium state and summarizing the expression for the modified thermodynamic…

General Physics · Physics 2025-12-01 Wen-Xiang Chen , Yao-Guang Zheng

We explore the possibility of gravitationally generated particle production in the scalar-tensor representation of $f(R,T)$ gravity. Due to the explicit nonminimal curvature-matter coupling in the theory, the divergence of the matter…

General Relativity and Quantum Cosmology · Physics 2022-09-02 Miguel A. S. Pinto , Tiberiu Harko , Francisco S. N. Lobo

Recently, a new class of modified gravity theories formulated via an additional scalar and vector field on top of the standard tensor field has been proposed. The direct implications of these theories are expected to be relevant for…

General Relativity and Quantum Cosmology · Physics 2018-09-11 Phongpichit Channuie , Davood Momeni

We propose a new model of a gravastar in (2+1) anti-de Sitter space-time. This new three dimensional configuration has three different regions with different equations of state: [I] Interior: 0 \leq r < r_1, \rho = -p ; [II] Shell: r_1 \leq…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Farook Rahaman , Saibal Ray , A. A. Usmani , Safiqul Islam

Among many alternative gravitational theories to General Relativity (GR), $f(R,T)$ gravity (where $R$ is the Ricci scalar and $T$ the trace of the energy-momentum tensor) has been widely studied recently. By adding a matter contribution to…

General Relativity and Quantum Cosmology · Physics 2017-07-05 Hermano Velten , Thiago R. P. Caramês

This article examines the dynamics of gravitational collapse in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ gravity, where $\mathcal{Q}=\mathcal{R}_{\mathrm{ab}}\mathcal{T}^{\mathrm{ab}}$. We consider self-gravitating anisotropic cylindrical…

General Relativity and Quantum Cosmology · Physics 2024-02-06 M. Sharif , Tayyab Naseer