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We investigate the modified $F(R)$ gravity theory with the function $F(R) = (1-\sqrt{1-2\lambda R-\sigma (\lambda R)^2})/\lambda$. The action is converted into Einstein$-$Hilbert action at small values of $\lambda$ and $\sigma$. The local…

General Relativity and Quantum Cosmology · Physics 2016-03-23 S. I. Kruglov

We use large volume N-body simulations to predict the clustering of dark matter in redshift space in f(R) modified gravity cosmologies. This is the first time that the nonlinear matter and velocity fields have been resolved to such a high…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-24 Elise Jennings , Carlton M. Baugh , Baojiu Li , Gong-Bo Zhao , Kazuya Koyama

This research paper deals with a transit dark energy cosmological model in $f(R, L_{m})$-gravity with observational constraints. For this, we consider a flat FLRW space-time and have taken a cosmological cosntant-like parameter $\beta$ in…

General Relativity and Quantum Cosmology · Physics 2023-05-03 Anirudh Pradhan , Dinesh Chandra Maurya , Gopikant K. Goswami , Aroonkumar Beesham

Here, we peruse cosmological usage of the most promising candidates of dark energy in the framework of $f(T)$ gravity theory. We reconstruct the different $f(T)$ modifed gravity models in the spatially flat FRW universe according to…

General Relativity and Quantum Cosmology · Physics 2016-10-12 Pameli Saha , Ujjal Debnath

We study a cosmological model in Rastall's theory of gravity in the framework of the flat FLRW metric. We formulate the value of the Hubble parameter, which contains two model parameters, $ \alpha $ and $ j $. Employing the Markov Chain…

General Relativity and Quantum Cosmology · Physics 2024-04-30 Shaily , Akanksha Singh , J. K. Singh , Saddam Hussain , Ratbay Myrzakulov

There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations is modified by the addition of a term proportional to some power, $n$, of the…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-29 M. C. F. Faria , C. J. A. P. Martins , F. Chiti , B. S. A. Silva

Properties of Braneworld models of dark energy are reviewed. Braneworld models admit the following interesting possibilities: (i) The effective equation of state can be w < -1 as well as w > -1. In the former case the expansion of the…

Astrophysics · Physics 2007-05-23 Varun Sahni

We show that the current accelerated expansion of the Universe can be explained without resorting to dark energy. Models of generalized modified gravity, with inverse powers of the curvature can have late time accelerating attractors…

Astrophysics · Physics 2008-11-26 Olga Mena , Jose Santiago , Jochen Weller

We study gravitational waves in viable $f(R)$ theories under a non-zero background curvature. In general, an $f(R)$ theory contains an extra scalar degree of freedom corresponding to a massive scalar mode of gravitational wave. For viable…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Louis Yang , Chung-Chi Lee , Chao-Qiang Geng

$f(R)$ gravity, capable of driving the late-time acceleration of the universe, is emerging as a promising alternative to dark energy. Various $f(R)$ gravity models have been intensively tested against probes of the expansion history,…

Astrophysics · Physics 2009-04-01 Xin-Juan Yang , Da-Ming Chen

We have investigated the evolution of a homogeneous isotropic background of the Universe and inhomogeneous subhorizon matter density perturbations in viable $f(R)$ models of present dark energy and cosmic acceleration analytically and…

Cosmology and Nongalactic Astrophysics · Physics 2011-08-05 Hayato Motohashi , Alexei A. Starobinsky , Jun'ichi Yokoyama

Dark energy can be characterized by a canonical scalar field, known as quintessence. Quintessence allows for a dynamical equation of state $-1 \le \omega \le -\frac{1}{3}$. A previous study by Oikonomou and Chatzarakis have shown that a…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-11 Sreerag Radhakrishnan , Sarath Nelleri , Navaneeth Poonthottathil

A modified theory of gravity with the function $F(R) = R\exp(\alpha R)$ instead of Ricci scalar $R$ in the Einstein$-$Hilbert action is considered and analyzed. The action of the model is converted into Einstein$-$Hilbert action at small…

General Relativity and Quantum Cosmology · Physics 2013-09-30 S. I. Kruglov

The availability of scaling solutions in renormalisation group improved versions of cosmology are investigated in the high-energy limit. We adopt $f(R)$-type models of quantum gravity which display an interacting ultraviolet fixed point at…

General Relativity and Quantum Cosmology · Physics 2018-05-16 Kevin Falls , Daniel F. Litim , Kostas Nikolakopoulos , Christoph Rahmede

We propose a model describing Einstein gravity coupled to a scalar field with an exponential potential. We show that the weak-field limit of the model has static solutions given by a gravitational potential behaving for large distances as…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Mariano Cadoni

The accelerated expansion of the universe poses a significant challenge to General Relativity. Non-local modifications to gravity have emerged as a compelling class of theories to address this dark energy puzzle. Building upon earlier…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Susobhan Mandal , S. Shankaranarayanan

This study effectively reconstructs a cosmological model utilizing covariant $f(Q)$ gravity within Connection-III and FLRW spacetime. The dynamic behavior of the reconstructed model is thoroughly analyzed using the Hubble parameter $H(z)$…

General Relativity and Quantum Cosmology · Physics 2025-01-15 S. A. Narawade , Santosh V. Lohakare , B. Mishra

In this study, FRW cosmology in modified gravity containing arbitrary function $f(R)$ is taken into consideration when our action are coupled with Weyl tensor. It is indicated that the bouncing solution emerges in the model while the…

General Physics · Physics 2015-03-31 Mohammad Ghanaatian , Farzad Milani

Braneworld models of dark energy are examined in the light of observations of high redshift type Ia supernovae. Braneworld models admit several novel and even exotic possibilities which include: (i) The effective equation of state of dark…

Astrophysics · Physics 2007-05-23 Ujjaini Alam , Varun Sahni

The problem of cosmic acceleration and dark energy is one of the mysteries presently posed in the scientific society that general relativity has not been able to solve. In this work, we have considered alternative models to explain this…

General Relativity and Quantum Cosmology · Physics 2022-12-01 M. Koussour , N. Myrzakulov , S. H. Shekh , M. Bennai
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