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Starting from the weak field limit, we discuss astrophysical applications of Extended Theories of Gravity where higher order curvature invariants and scalar fields are considered by generalizing the Hilbert-Einstein action linear in the…

General Relativity and Quantum Cosmology · Physics 2015-02-25 A. Stabile , S. Capozziello

We perform a dynamical system analysis of Myrzakulov or F(R, T) gravity, which is a subclass of affinely connected metric theories, where ones uses a specific but non-special connection, which allows for non-zero curvature and torsion…

General Relativity and Quantum Cosmology · Physics 2022-11-30 G. Papagiannopoulos , Spyros Basilakos , Emmanuel N. Saridakis

In this paper, we have performed the dynamical system analysis of $f(T)$ gravity cosmological models at both background and perturbation levels. We have presented three models pertaining to three distinct functional forms of $f(T)$. The…

General Relativity and Quantum Cosmology · Physics 2024-03-20 L. K. Duchaniya , Kanika Gandhi , B. Mishra

Classical gravity coupled to a CFT$_4$ (matter) is considered. The effect of the quantum dynamics of matter on gravity is studied around maximally symmetric spaces (flat, de Sitter and Anti de Sitter). The structure of the graviton…

General Relativity and Quantum Cosmology · Physics 2023-12-11 Jewel K. Ghosh , Elias Kiritsis , Francesco Nitti , Valentin Nourry

We study the problem of the instability of inhomogeneous radiation universes in quadratic lagrangian theories of gravity written as a system of evolution equations with constraints. We construct formal series expansions and show that the…

General Relativity and Quantum Cosmology · Physics 2021-04-21 Spiros Cotsakis , Dimitrios Trachilis

We investigate the modified gravity theories in terms of the effective dark energy models. We compare the cosmic expansion history and the linear growth in different models. We also study the evolution of linear cosmological perturbations…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Seokcheon Lee

This article focuses on the formulation of some scalar factors which are uniquely expressed in terms of matter variables for dynamical charged dissipative cylindrical geometry in a standard gravity model $\mathcal{R}+\Phi\mathcal{Q}$…

General Relativity and Quantum Cosmology · Physics 2022-09-05 M. Sharif , Tayyab Naseer

We perform a thorough study of the theoretical consistency of recently proposed, viable, quadratic modifications of gravity that are functions of the the Gauss-Bonnet invariant, regarding the stability of their perturbations around vacuum,…

General Relativity and Quantum Cosmology · Physics 2010-05-27 Israel Quiros , Eduardo Teste

In this paper, we consider the effect of electromagnetic field to the definition of complexity in the context of $f(G,T)$ gravity, where $G$ and $T$ express the Gauss-Bonnet term and energy-momentum tensor, respectively. The physical…

General Relativity and Quantum Cosmology · Physics 2023-06-14 M. Sharif , K. Hassan

In this paper, we have investigated the role of different fluid parameters particularly electromagnetic field and $f(R)$ corrections on the evolution of cylindrical compact object. We have explored the modified field equations, kinematical…

General Physics · Physics 2016-12-08 Z. Yousaf , M. Zaeem-ul-Haq Bhatti

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

We investigate the evolution of the linear cosmological perturbations in f(R) gravity, an alternative to dark energy for explaining the late-time cosmic acceleration. We numerically calculate the early-time evolution with an approximation…

Cosmology and Nongalactic Astrophysics · Physics 2011-08-16 Je-An Gu , Tse-Chun Wang , Yen-Ting Wu , Pisin Chen , W-Y. Pauchy Hwang

In this work, we use the dynamical system approach to explore the cosmological background evolution of the scalar-tensor representation of $f(R,T)$ gravity, where $R$ is the Ricci scalar and $T$ is the trace of the stress-energy tensor. The…

General Relativity and Quantum Cosmology · Physics 2024-04-04 Tiago B. Gonçalves , João Luís Rosa , Francisco S. N. Lobo

We study the growth of structures in modified gravity models where the Poisson equation and the relationship between the two Newtonian potentials are modified by explicit functions of space and time. This parameterisation applies to the…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-24 Philippe Brax , Patrick Valageas

This paper is devoted to analyze the dynamical instability of a self-gravitating object undergoes to collapse process. We take the framework of generalized teleparallel gravity with cylindrically symmetric gravitating object. The matter…

General Relativity and Quantum Cosmology · Physics 2016-10-31 Abdul Jawad , Davood Momeni , Shamaila Rani , Ratbay Myrzakulov

In this paper, we derive the field equations of modified Gauss-Bonnet gravity termed as $f(R,G)$ gravity for the non-flat Friedmann-Robertson-Walker (FRW) spacetime. We utilize the dynamical system approach to study the cosmic dynamics of…

General Relativity and Quantum Cosmology · Physics 2025-01-22 Ashutosh Singh

We investigate the scalar sector of linear cosmological perturbations in quadratic gravity. Working in the Einstein frame, we derive the equations of motion in a gauge-independent manner and express them in terms of three sets of…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Adrian Palomares , Ying-li Zhang , Jinsu Kim

In this paper we study scalar perturbations of the metric for nonlinear $f(R)$ models. We consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. We investigate the astrophysical approach in the case…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-04 Maxim Eingorn , Jan Novák , Alexander Zhuk

This thesis explores the late-time cosmic acceleration within the framework of $f(R,T)$ gravity, a general relativity modification that incorporates the Ricci scalar $R$ and the trace of the energy-momentum tensor $T$. Motivated by…

General Relativity and Quantum Cosmology · Physics 2025-07-29 Parbati Sahoo

We use observations related to the variation of fundamental constants, in order to impose constraints on the viable and most used $f(T)$ gravity models. In particular, for the fine-structure constant we use direct measurements obtained by…

General Relativity and Quantum Cosmology · Physics 2017-04-18 Rafael C. Nunes , Alexander Bonilla , Supriya Pan , Emmanuel N. Saridakis