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Related papers: Some aspects of generalized modified gravity model…

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We consider f(R,T) modified theory of gravity, in which the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar and the trace of the energy-momentum tensor of the matter, in order to investigate the dark-matter…

General Relativity and Quantum Cosmology · Physics 2016-11-02 Raziyeh Zaregonbadi , Mehrdad Farhoudi , Nematollah Riazi

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

Recent results show that important singularities in General Relativity can be naturally described in terms of finite and invariant canonical geometric objects. Consequently, one can write field equations which are equivalent to Einstein's…

General Relativity and Quantum Cosmology · Physics 2014-03-06 Ovidiu Cristinel Stoica

Despite the experimental success of general relativity in the scales it has been tested, there are still some inconsistencies, such as explaining the acceleration of the universe and singularities. $f(R)$ gravity has emerged to provide…

General Relativity and Quantum Cosmology · Physics 2023-12-12 A. C. L. Santos , R. V. Maluf , C. R. Muniz

In the context of f(R) modified gravity theories we determine that the black holes existence is determined by the sign of a parameter dependent of the mass, the charge, the spin and the scalar curvature. We obtain the different…

General Relativity and Quantum Cosmology · Physics 2012-02-07 J. A. R. Cembranos , A. de la Cruz-Dombriz , P. Jimeno Romero

We consider generalized energy conditions in modified theories of gravity by taking into account the further degrees of freedom related to scalar fields and curvature invariants. The latter are usually recast as generalized {\it geometrical…

General Relativity and Quantum Cosmology · Physics 2014-02-14 Salvatore Capozziello , Francisco S. N. Lobo , José P. Mimoso

When recent observational evidence and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of…

Cosmology and Nongalactic Astrophysics · Physics 2012-05-17 Jonathan A. Pearson

Black holes are one of the most fascinating predictions of general relativity. They are the natural product of the complete gravitational collapse of matter and today we have a body of observational evidence supporting the existence of…

General Relativity and Quantum Cosmology · Physics 2023-07-26 Cosimo Bambi

In modified theories of gravity, higher curvature terms may be added to the Einstein-Hilbert action. Conventionally, the effects of the higher curvature terms on the black hole thermodynamics are rather difficult to obtain. In this paper,…

General Relativity and Quantum Cosmology · Physics 2022-10-05 Yong Xiao

The review of basic cosmological properties of four-dimensional F(R)-gravity, including FRW equations of motion and its accelerating solutions, generalized fluid and scalar-tensor representation of the theory is done. Cosmological…

High Energy Physics - Theory · Physics 2015-05-19 Shin'ichi Nojiri , Sergei D. Odintsov

We consider the basic physical properties of matter forming a thin accretion disc in the static and spherically symmetric space-time metric of the vacuum $f(R)$ modified gravity models. The Lagrangian of the generalized gravity theory is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 C. S. J. Pun , Z. Kovacs , T. Harko

Emergent modified gravity presents a new set of generally covariant gravitational theories in which the space-time metric is not directly given by one of the fundamental fields. A metric compatible with the modified dynamics of gravity is…

General Relativity and Quantum Cosmology · Physics 2024-04-09 Martin Bojowald , Erick I. Duque

An obvious criterion to classify theories of modified gravity is to identify their gravitational degrees of freedom and their coupling to the metric and the matter sector. Using this simple idea, we show that any theory which depends on the…

General Relativity and Quantum Cosmology · Physics 2017-03-01 Xavier Calmet , Iberê Kuntz

Charged black holes arise as solutions of General Relativity (GR) coupled to Maxwell theory. As functions of the mass and charge, they can exhibit extremal behavior, in which case they are stable against thermal decay. (Quantum) corrections…

General Relativity and Quantum Cosmology · Physics 2025-04-30 Mattia Damia Paciarini , Manuel Del Piano , Stefan Hohenegger , Francesco Sannino

We suggest the modified gravity where some arbitrary function of Gauss-Bonnet (GB) term is added to Einstein action as gravitational dark energy. It is shown that such theory may pass solar system tests. It is demonstrated that modified GB…

High Energy Physics - Theory · Physics 2010-04-06 Shin'ichi Nojiri , Sergei D. Odintsov

We review the recent literature on modified theories of gravity in the Palatini approach. After discussing the motivations that lead to consider alternatives to Einstein's theory and to treat the metric and the connection as independent…

General Relativity and Quantum Cosmology · Physics 2011-05-09 Gonzalo J. Olmo

Taking advantage of the representation of dilatonic gravity with the $R^2$-term under the form of low-derivative dilatonic gravity coupled to an additional scalar, we construct a general renormalizable model motivated by this theory. Exact…

High Energy Physics - Theory · Physics 2016-09-06 E. Elizalde , P. Fosalba-Vela , S. Naftulin , S. D. Odintsov

We present a comprehensive investigation of cosmological constraints on the class of vector field formulations of modified gravity called Generalized Einstein-Aether models. Using linear perturbation theory we generate cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-25 J. Zuntz , T. G. Zlosnik , F. Bourliot , P. G. Ferreira , G. D. Starkman

The late time acceleration of the Universe has challenged contemporary cosmology since its discovery. General Relativity explains this phenomenon by introducing the cosmological constant, named the standard cosmological model…

General Relativity and Quantum Cosmology · Physics 2024-01-02 Simran Arora

In this letter, we show that any solution of general relativity (GR) that can be rendered spatially flat by a coordinate change is also a solution of the self-accelerating branch of the minimal theory of massive gravity (MTMG), with or…

General Relativity and Quantum Cosmology · Physics 2018-11-28 Antonio De Felice , François Larrouturou , Shinji Mukohyama , Michele Oliosi