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We analyze the stability of the Einstein static universe by considering homogeneous scalar perturbations in the context of f(R) modified theories of gravity. By considering specific forms of f(R), the stability regions of the solutions are…

General Relativity and Quantum Cosmology · Physics 2012-06-22 Christian G. Boehmer , Lukas Hollenstein , Francisco S. N. Lobo

A brief introduction on the issue of stability in generalized modified gravity is presented and the dynamical system methods are used in the investigation of the stability of spatially flat homogeneous cosmologies within a large class of…

General Relativity and Quantum Cosmology · Physics 2008-11-18 Guido Cognola , Sergio Zerbini

Dynamical system methods are used in the study of the stability of spatially flat homogeneous cosmologies within a large class of generalized modified gravity models in the presence of a relativistic matter-radiation fluid. The present…

High Energy Physics - Theory · Physics 2008-12-18 Guido Cognola , Sergio Zerbini

Among the remaining viable theories that can successfully describe the late-time era is the $k$-Essence theory and in this work we study in detail the phase space of $k$-Essence $f(R)$ gravity in vacuum. This theory can describe in a viable…

General Relativity and Quantum Cosmology · Physics 2020-05-20 V. K. Oikonomou , N. Chatzarakis

We examine in this paper the stability analysis in $f(R; T; R_{\mu\nu}T^{\mu\nu})$ modified gravity, where $R$ and $T$ are the Ricci scalar and the trace of the energy-momentum tensor, respectively. By considering the flat Friedmann…

General Relativity and Quantum Cosmology · Physics 2016-12-15 E. H. Baffou , M. J. S. Houndjo , J. Tossa

The so called $f(X)$ hybrid metric-Palatini gravity presents a unique viable generalisation of the $f(R)$ theories within the metric-affine formalism. Here the cosmology of the $f(X)$ theories is studied using the dynamical system approach.…

General Relativity and Quantum Cosmology · Physics 2015-09-28 Sante Carloni , Tomi Koivisto , Francisco S. N. Lobo

Within the context of modified gravity and dark energy scenarios of the accelerating universe, we study the stability of de Sitter space with respect to inhomogeneous perturbations using a gauge-independent formalism. In modified gravity…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Valerio Faraoni

The starting point in this note is $f(R)$ modified gravity in a cosmological setting. We assume a spatially flat Universe to describe late-time cosmology and the perfect-fluid equation of state $p=\omega\rho$ to model the hypothesized dark…

General Relativity and Quantum Cosmology · Physics 2017-06-13 Peter K. F. Kuhfittig

We investigate the cosmological dynamics of FHDE within $f(T)$ gravity by employing the dynamical system approach in a spatially flat FRW background. By introducing appropriate dimensionless variables, the field equations are reformulated…

General Relativity and Quantum Cosmology · Physics 2026-02-23 Elangbam Chingkheinganba Meetei , S. Surendra Singh

Cosmological approaches of autonomous dynamical system in the framework of $f(T)$ gravity are investigated in this paper. Our methods applied to flat Friedmann-Robertson-Walker equations in $f(T)$ gravity, consist to extract dynamical…

General Relativity and Quantum Cosmology · Physics 2018-05-02 M. G. Ganiou , P. H. Logbo , M. J. S. Houndjo , J. Tossa

We study in detail the phase space of a Friedmann-Robertson-Walker Universe filled with various cosmological fluids which may or may not interact. We use various expressions for the equation of state, and we analyze the physical…

General Relativity and Quantum Cosmology · Physics 2017-09-13 S. D. Odintsov , V. K. Oikonomou , Petr V. Tretyakov

In this paper we investigate cosmological dynamics on the normal branch of a DGP-inspired scenario within a phase space approach where induced gravity is modified in the spirit of $f(R)$-theories. We apply the dynamical system analysis to…

General Relativity and Quantum Cosmology · Physics 2015-05-19 Kourosh Nozari , Faeze Kiani

We investigate a simple generalization of the metric exponential $f(R)$ gravity theory that is cosmologically viable and compatible with solar system tests of gravity. We show that, as compared to other viable $f(R)$ theories, its steep…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-26 M. O'Dwyer , S. E. Joras , I. Waga

We investigate cosmological solutions of f(R,T) modified theories of gravity for perfect fluid in spatially FLRW metric through phase space analysis, where R is Ricci scalar and T denotes the trace of energy-momentum tensor of matter…

General Relativity and Quantum Cosmology · Physics 2017-05-23 Hamid Shabani , Mehrdad Farhoudi

In this work we study the phase-space analysis of generalized Rastall gravity (GRG) which has recently been introduced as a modification to the original version of Rastall gravity (RG). In GRG, the coupling parameter assumes a dynamical…

General Relativity and Quantum Cosmology · Physics 2022-06-01 Hamid Shabani , Hooman Moradpour , Amir Hadi Ziaie

In this work we explore the dynamical system phase space of Einstein-Gauss-Bonnet theory in the cosmological minisuperspace. This approach binds the main features of the theory through a system of autonomous differential equations, in the…

General Relativity and Quantum Cosmology · Physics 2022-11-14 Konstantinos F. Dialektopoulos , Jackson Levi Said , Zinovia Oikonomopoulou

We analyze the stability of the Einstein static closed and open universe in two types of exponential $f(T)$ gravity theories. We show that the stable solutions exist in these two models. In particular, we find that large regions of…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Jung-Tsung Li , Chung-Chi Lee , Chao-Qiang Geng

We employ a linear stability analysis approach to explore the dynamics of matter and curvature-driven dark energy interactions within the framework of two types of viable $f(R)$ gravity models. The interaction is modeled via a source term…

General Relativity and Quantum Cosmology · Physics 2025-04-21 Anirban Chatterjee , Yungui Gong

Two accelerating cosmological models are presented in symmetric teleparallel $f(Q)$ gravity, $Q$ be the non-metricity. The models are constructed based on the assumptions of two different functional forms of $f(Q)$ and a dynamically…

General Relativity and Quantum Cosmology · Physics 2022-05-25 S. A. Narawade , Laxmipriya Pati , B. Mishra , S. K. Tripathy

The $f(T)$ gravity is one of the extensions of teleparallel equivalent of general relativity, in which more general functions of the torsion scalar $T$ can be described. With the proposed functional form of $f(T) = \alpha T - \beta u^{-n} +…

General Relativity and Quantum Cosmology · Physics 2026-04-14 Suraj Kumar Behera , S. A. Kadam , Pratik P. Ray , B. Mishra