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The possible emergence of compact stars has been investigated in the recently introduced modified Gauss-Bonnet $f(\mathcal{G},T)$ gravity, where $\mathcal{G}$ is the Gauss-Bonnet term and ${T}$ is the trace of the energy-momentum tensor.…

General Relativity and Quantum Cosmology · Physics 2017-10-18 M. Farasat Shamir , Mushtaq Ahmad

In this paper, the quasi static-approximation on the hydrodynamics of compact objects is proposed in $f(R, T)$ gravity, where $R$ is the scalar curvature and $T$ is the trace of stress-energy tensor, by exploring the axial and reflection…

General Relativity and Quantum Cosmology · Physics 2024-08-26 Z. Yousaf , Kazuharu Bamba , M. Z. Bhatti , U. Farwa

This work deals with the computation of the power spectrum of large-scale structure using the dynamical system approach for a multi-fluid universe in scalar-tensor theory of gravity. We use the $1+3$ covariant approach to obtain evolution…

General Relativity and Quantum Cosmology · Physics 2022-08-31 Joseph Ntahompagaze , Amare Abebe , Manasse R. Mbonye

In an $n$-dimensional Friedmann-Robertson-Walker metric, it is rigorously shown that any analytical theory of gravity $f(R,{\cal G})$, where $R$ is the curvature scalar and $\cal G$ is the Gauss-Bonnet topological invariant, can be…

General Relativity and Quantum Cosmology · Physics 2019-10-02 Salvatore Capozziello , Carlo Alberto Mantica , Luca Guido Molinari

The general relativistic perturbations of scalar-tensor theories (STT) of gravity are studied in a manifestly gauge invariant Hamiltonian formalism. After the derivation of the Hamiltonian equations of motion in this framework, the gauge…

General Relativity and Quantum Cosmology · Physics 2015-06-08 Yu Han , Kristina Giesel , Yongge Ma

This work is concerned to study the bouncing nature of the universe for an isotropic configuration of fluid $\mathcal{T}_{\alpha\beta}$ and Friedmann-Lema\^{i}tre-Robertson-Walker metric scheme. This work is carried out under the novel…

General Relativity and Quantum Cosmology · Physics 2023-02-08 Z. Yousaf , M. Z. Bhatti , H. Aman , P. K. Sahoo

Scalar-tensor gravity is the simplest and best understood modification of general relativity, consisting of a real scalar field coupled directly to the Ricci scalar curvature. Models of this type have self-accelerating solutions. In an…

Astrophysics · Physics 2009-09-17 Gabriela Barenboim , Joseph Lykken

In recent few years, the Gauss-Bonnet $f(\mathcal{G},\mathrm{\textit{T}})$ theory of gravity has fascinated considerable researchers owing to its coupling of trace of the stress-energy tensor $T$ with the Gauss-Bonnet term $\mathcal{G}$. In…

General Relativity and Quantum Cosmology · Physics 2023-04-14 Mushtaq Ahmad , M. Farasat Shamir , G. Mustafa

We investigate the first and second order cosmological perturbation equations in f(R) modified gravity theory and provide the equation of motion of second order scalar induced gravitational waves. We find that the effects of modified…

General Relativity and Quantum Cosmology · Physics 2024-11-14 Jing-Zhi Zhou , Yu-Ting Kuang , Di Wu , Fei-Yu Chen , H. Lü , Zhe Chang

We study effects of cosmic fluids on finite-time future singularities in modified $f(R,G)$-gravity, where $R$ and $G$ are the Ricci scalar and the Gauss-Bonnet invariant, respectively. We consider the fluid equation of state in the general…

General Relativity and Quantum Cosmology · Physics 2010-11-15 Olesya Gorbunova , Lorenzo Sebastiani

In this paper we show how the covariant gauge invariant equations for the evolution of scalar, vector and tensor perturbations for a generic $f(R)$-gravity theory can be recast in order to exploit the power of dynamical system methodology.…

One of the possible potential candidates for describing the universe's rapid expansion is modified gravity. In the framework of the modified theory of gravity $f(R,G)$, the present work features the materialization of anisotropic matter,…

General Relativity and Quantum Cosmology · Physics 2022-06-29 W. U. Rahman , M. Ilyas , Z. Yousaf , S. Ullah , F. Khan , R. khan

In this paper, we explore the source of gravitational radiation in the context of $f(R)$ gravity by considering axially symmetric dissipative dust under geodesic condition. We evaluate scalars associated with electric and magnetic parts of…

General Relativity and Quantum Cosmology · Physics 2017-03-08 M. Sharif , Aisha Siddiqa

This manuscript aims to establish the gravitational junction conditions(JCs) for the $f(\mathcal{G},~T)$ gravity. In this gravitational theory, $f$ is an arbitrary function of Gauss-Bonnet invariant $\mathcal{G}$ and the trace of the…

General Relativity and Quantum Cosmology · Physics 2022-07-14 M. Z. Bhatti , Z. Yousaf , M. Yousaf

The basic objective of this investigation is to explore the impact of a novel gravitational modification, specifically, the $f(\mathcal{G}, \mathbf{T}^2)$ (where $\mathbf{T}^2 \equiv T_{\alpha\beta}T^{\alpha\beta}$, $T^{\alpha\beta}$…

General Relativity and Quantum Cosmology · Physics 2022-04-12 Z. Yousaf , M. Z. Bhatti , S. Khan , P. K. Sahoo

The Gauss-Bonnet invariant connects foundational aspects of geometry with physical phenomena in a variety of ways. Teleparallel gravity offers a novel direction in which to use the Gauss-Bonnet invariant to go beyond standard cosmology. In…

General Relativity and Quantum Cosmology · Physics 2026-04-21 Shivam Kumar Mishra , Jackson Levi Said , B. Mishra

This paper is devoted to investigate the recently proposed modified Gauss-Bonnet $f(\mathcal{G},T)$ gravity, with $\mathcal{G}$, the Gauss-Bonnet term, coupled with ${T}$, the trace of energy-momentum tensor. We have used the Noether…

General Relativity and Quantum Cosmology · Physics 2017-07-12 M. Farasat Shamir , Mushtaq Ahmad

Recent findings from the Neutron Star Interior Composition Explorer (NICER) have opened up opportunities to investigate the potential coupling between matter and geometry, along with its resulting physical implications. Millisecond pulsars…

General Relativity and Quantum Cosmology · Physics 2023-06-21 G. G. L. Nashed

Modified gravity theories on cosmic scales have three key deviations from general relativity. They can cause cosmic acceleration without a physical, highly negative pressure fluid, can cause a gravitational slip between the two metric…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-04 Eric V. Linder

We analyze a fully geometric approach to dark energy in the framework of $F(R,{\cal G})$ theories of gravity, where $R$ is the Ricci curvature scalar and ${\cal G}$ is the Gauss-Bonnet topological invariant. The latter invariant naturally…

General Relativity and Quantum Cosmology · Physics 2020-11-09 Micol Benetti , Simony Santos da Costa , Salvatore Capozziello , Jailson S. Alcaniz , Mariafelicia De Laurentis