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We investigate cosmological dynamics based on $f(R)$ gravity in the Palatini formulation. In this study we use the dynamical system methods. We show that the evolution of the Friedmann equation reduces to the form of the piece-wise smooth…

General Relativity and Quantum Cosmology · Physics 2018-05-30 Marek Szydlowski , Aleksander Stachowski

We study the cosmological dynamics of a class of symmetric teleparallel gravity theories known as ``newer general relativity'' using the methods of dynamical systems, restricted to the case of vacuum solutions with a spatially flat…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Manuel Hohmann , Ulbossyn Ualikhanova

We present a Friedmann-Robertson-Walker (FRW) quantum cosmological model within the framework of Finslerian geometry. In this work, we consider a specific fluid. We obtain the corresponding Wheeler-DeWitt equation as the usual constraint…

General Physics · Physics 2019-11-04 S S De , Farook Rahaman , Nupur Paul

We construct a compact phase space for flat FLRW spacetimes with standard matter described by a perfect fluid with a barotropic equation of state for general f(R) theories of gravity, subject to certain conditions on the function f. We then…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Mohamed Abdelwahab , Rituparno Goswami , Peter K. S. Dunsby

In this paper we consider FRW cosmology in $F(R,\phi)$ gravity. It is shown that in particular cases the bouncing behavior may appears in the model whereas the equation of state (EoS) parameter may crosses the phantom divider. For the…

General Physics · Physics 2015-03-17 H. Farajollahi , M. Setare , F. Milani , F. Tayebi

In this paper, the dynamical system analysis has been performed to analyze the dynamical behavior of the Universe in $f(R,L_m,T)$ gravity with a scalar field. A well motivated potential function and the linear form of the functional…

General Relativity and Quantum Cosmology · Physics 2026-04-21 R. R. Panchal , Divya G. Sanjava , A. H. Hasmani , B. Mishra

We study the dynamics of spatially homogeneous and isotropic spacetimes containing a fluid undergoing microscopic velocity diffusion in a cosmological scalar field. After deriving a few exact solutions of the equations, we continue by…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Artur Alho , Simone Calogero , Maria P. Machado Ramos , Ana J. Soares

We consider a model of the Universe in which the matter content is in the form of discrete islands, rather than a continuous fluid. In the appropriate limits the resulting large-scale dynamics approach those of a Friedmann-Robertson-Walker…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-07 Timothy Clifton , Pedro G. Ferreira

The dynamics of perfect fluid as a source in the context of modified gravity, specifically $f(Q,T)$ gravity, are examined within the Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model. This gravity is a generic function of the…

General Relativity and Quantum Cosmology · Physics 2024-08-02 S. H. Shekh , Anirudh Pradhan , S. P. Gaikwad , K. R. Mule

The dynamics of a tachyon field plus a barotropic fluid is investigated in spatially curved FRW universe. We perform a phase-plane analysis and obtain scaling solutions accompanying with a discussion on their stability. Furthermore, we…

High Energy Physics - Theory · Physics 2010-03-17 Jian-Li Li , Jian-Pin Wu

We discuss a mechanism that induces a time-dependent vacuum energy on cosmological scales. It is based on the instability induced renormalization triggered by the low energy quantum fluctuations in a Universe with a positive cosmological…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Alfio Bonanno , Sante Carloni

The dissipative dynamics of an expanding massless gas with constant cross section in a spatially flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe is studied. The mathematical problem of solving the full nonlinear relativistic…

High Energy Physics - Phenomenology · Physics 2016-12-14 D. Bazow , G. S. Denicol , U. Heinz , M. Martinez , J. Noronha

We study noncommutative classical Friedmann-Robertson-Walker cosmological models. The constant curvature of the spatial sections can be positive ($k=1$), negative ($k=-1$) or zero ($k=0$). The matter is represented by a perfect fluid with…

General Relativity and Quantum Cosmology · Physics 2017-01-06 G. Oliveira-Neto , A. R. Vaz

The origin of the accelerated expansion of the Universe remains an unsolved mystery in Cosmology. In this work we consider a spatially flat Friedmann-Robertson-Walker (FRW) Universe with non-relativistic matter and a single scalar field…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Remya Nair , Sanjay Jhingan , Deepak Jain

Our aim in this paper is two-fold. We establish a novel geometric characterization of the Roberson-Walker (RW) spacetime and, along the process, we find a canonical form of the RW metric associated to an arbitrary timelike curve and an…

General Relativity and Quantum Cosmology · Physics 2024-09-26 Marc Mars , Raül Vera

In this work, we present a phase space analysis of a spatially flat Friedmann $-$Robertson$-$Walker (FRW) model in which the dark matter fluid is modeled as an imperfect fluid having bulk viscosity. The bulk viscosity is governed by the…

General Relativity and Quantum Cosmology · Physics 2019-01-23 Yoelsy Leyva

We discuss flat Friedmann-Lemaitre-Robertson-Walker (FLRW) metric-affine cosmology where the metric and connection as well as the matter energy-momentum and hypermomentum all obey the symmetry of spatial homogeneity and isotropy. In…

General Relativity and Quantum Cosmology · Physics 2026-04-07 Ilaria Andrei , Damianos Iosifidis , Laur Järv , Margus Saal

We analyze the properties of a generic cosmological fluid described by the van der Waals equation of state. Exact solutions for the energy density evolution are found as implicit functions of the scale factor for a flat…

General Relativity and Quantum Cosmology · Physics 2016-02-11 Rudinei C. S. Jantsch , Marcus H. B. Christmann , Gilberto M. Kremer

We explore the dynamical properties of a cosmological model that includes viscous effects in the dark matter sector of the fluid equations in a flat Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. The bulk viscous effects are…

General Relativity and Quantum Cosmology · Physics 2022-11-14 Gilberto Aguilar-Pérez , Ana A. Avilez-López , Miguel Cruz

We systematically study the evolution of the Friedmann-Robertson-Walker (FRW) universe coupled with a cosmological constant $\Lambda$ and a perfect fluid that has the equation of state $p=w\rho$, where $p$ and $\rho$ denote, respectively,…