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We study linear perturbations around time dependent spherically symmetric solutions in the Lambda_3 massive gravity theory, which self-accelerate in the vacuum. We find that the dynamics of the scalar perturbations depend on the coordinate…

High Energy Physics - Theory · Physics 2015-06-16 Nima Khosravi , Gustavo Niz , Kazuya Koyama , Gianmassimo Tasinato

We continue the exploration of the consistency of a modified-gravity theory that generalizes General Relativity by including a dynamical torsion in addition to the dynamical metric. The six-parameter theory we consider was found to be…

General Relativity and Quantum Cosmology · Physics 2018-06-13 Vasilisa Nikiforova , Thibault Damour

We study a scalar field in curved space in three dimensions. We obtain a static perturbative solution and show that this solution satisfies the exact equations in the asymptotic region at infinity. The new solution gives rise to a…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Tolga Birkandan , M. Hortacsu

The properties of metric perturbations are determined in the context of an expanding Universe governed by a modified theory of gravity with a non-minimal coupling between curvature and matter. We analyse the dynamics of the 6 components of…

General Relativity and Quantum Cosmology · Physics 2025-01-07 Miguel Barroso Varela , Orfeu Bertolami

We investigate the cosmology of SO(3)-invariant massive gravity with 5 degrees of freedom. In contrast with previous studies, we allow for a non-trivial fiducial metric, which can be justified by invoking, for example, a dilaton-like global…

High Energy Physics - Theory · Physics 2015-06-19 David Langlois , Shinji Mukohyama , Ryo Namba , Atsushi Naruko

In this paper, we study the properties of gravitational waves in the scalar-tensor-vector gravity theory. The polarizations of the gravitational waves are investigated by analyzing the relative motion of the test particles. It is found that…

General Relativity and Quantum Cosmology · Physics 2019-12-19 Yunqi Liu , Wei-Liang Qian , Yungui Gong , Bin Wang

We study a class of static spherically symmetric vacuum solutions in modified teleparallel gravity solving the field equations for a specific model Ansatz, requiring the torsion scalar $T$ to be constant. We discuss the models falling in…

General Relativity and Quantum Cosmology · Physics 2024-05-21 Marco Calzá an Lorenzo Sebastiani

We study the structure of scalar-tensor theories of gravity based on derivative couplings between the scalar and the matter degrees of freedom introduced through an effective metric. Such interactions are classified by their tensor…

General Relativity and Quantum Cosmology · Physics 2014-03-26 Miguel Zumalacárregui , Juan García-Bellido

Cosmology in extended theories of gravity is considered assuming the Palatini variational principle, for which the metric and connection are independent variables. The field equations are derived to linear order in perturbations about the…

Astrophysics · Physics 2015-06-24 Tomi Koivisto , Hannu Kurki-Suonio

We consider a model for gravity that is invariant under global scale transformations. It includes one extra real scalar field coupled non-minimally to the gravity fields. In this model all the dimensionful parameters like the gravitational…

General Relativity and Quantum Cosmology · Physics 2012-02-06 Pankaj Jain , Purnendu Karmakar , Subhadip Mitra , Sukanta Panda , Naveen K. Singh

This paper aims to formulate certain scalar factors associated with matter variables for self-gravitating non-static cylindrical geometry by considering a standard model $\mathcal{R}+\zeta\mathcal{Q}$ of…

General Relativity and Quantum Cosmology · Physics 2023-11-02 M. Sharif , T. Naseer

The modified theories of gravity, especially the f(R) theory, have attracted much attention in recent years. In this context, we explore static plane symmetric vacuum solutions using the metric approach of this theory. The field equations…

General Relativity and Quantum Cosmology · Physics 2010-06-21 M. Sharif , M. Farasat Shamir

We explore the evolutionary behaviors of compact objects in a modified gravitational theory with the help of structure scalars. Particularly, we consider the spherical geometry coupled with heat and radiation emitting shearing viscous…

General Relativity and Quantum Cosmology · Physics 2016-04-12 Z. Yousaf , Kazuharu Bamba , M. Zaeem ul Haq Bhatti

The study of perturbation of self-gravitating celestial cylindrical object have been carried out in this paper. We have designed a framework to construct the collapse equation by formulating the modified field equations with the background…

General Physics · Physics 2017-11-08 M. Zaeem-ul-Haq Bhatti , Z. Yousaf

We find an exact solution of Scalar-Tensor-Vector Gravity field equations that represents a black hole embedded in an expanding universe. This is the first solution of the kind found in the theory. We analyze the properties of the apparent…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Daniela Pérez , Gustavo E. Romero

This note includes results of a study of stationary spherically symmetric ``dark holes'', objects merging central black holes and peripheral scalar graviton dark haloes arising in the framework of the modified gravity -- the quartet-metric,…

General Relativity and Quantum Cosmology · Physics 2025-07-15 Yu. F. Pirogov , O. V. Zenin

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

In arbitrary higher dimension, we consider the combination of Lovelock gravity alongside a scalar-tensor action built out of higher order operators and Euler densities. The latter action is constructed in such a way as to ensure conformal…

General Relativity and Quantum Cosmology · Physics 2023-05-10 Eugeny Babichev , Christos Charmousis , Mokhtar Hassaine , Nicolas Lecoeur

A scalar-tensor theory of gravity is considered wherein the gravitational coupling $G$ and the speed of light $c$ are admitted as space-time functions and combine to form the definition of the scalar field $\phi$. The varying $c$…

General Relativity and Quantum Cosmology · Physics 2023-04-05 Rodrigo R. Cuzinatto , Rajendra P. Gupta , Pedro J. Pompeia

Massive gravity is a good theoretical laboratory to study modifications of General Relativity. The theory offers a concrete set-up to study models of dark energy, since it admits cosmological self-accelerating solutions in the vacuum, in…

High Energy Physics - Theory · Physics 2015-06-15 Gianmassimo Tasinato , Kazuya Koyama , Gustavo Niz