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In this paper, we consider a gravitational action containing a combination of the Ricci scalar, $R$, and the topological Gauss--Bonnet term, $G$. Specifically, we study the cosmological features of a particular class of modified gravity…

General Relativity and Quantum Cosmology · Physics 2023-03-15 Francesco Bajardi , Rocco D'Agostino

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…

General Relativity and Quantum Cosmology · Physics 2019-11-22 S. K. J. Pacif , Md Salahuddin Khan , L. K. Paikroy , Shalini Singh

Recently, a new field of study called fractional cosmology has emerged. It uses fractional calculus to modify the standard derivative equations and change the Friedmann equations. The evolution of cosmic species densities is also affected…

General Relativity and Quantum Cosmology · Physics 2023-05-01 Genly Leon , Miguel A. García-Aspeitia , Guillermo Fernandez-Anaya , Alberto Hernández-Almada , Juan Magaña , Esteban González

We compile an updated list of 38 measurements of the Hubble parameter $H(z)$ between redshifts $0.07 \leq z \leq 2.36$ and use them to place constraints on model parameters of constant and time-varying dark energy cosmological models, both…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-25 Omer Farooq , Foram Madiyar , Sara Crandall , Bharat Ratra

Using the mathematical definitions of deceleration and jerk parameters we obtain a general differential equation for squared Hubble parameter. For a constant jerk, this differential equation leads to an exact function for Hubble parameter.…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-21 Hassan Amirhashchi , Soroush Amirhashchi

In this paper, we consider a class of five-dimensional Ricci-flat vacuum solutions, which contain two arbitrary functions $\mu(t)$ and $\nu(t)$. It is shown that $\mu(t)$ can be rewritten as a new arbitrary function $f(z)$ in terms of…

Astrophysics · Physics 2009-11-11 Lixin Xu , Hongya Liu , Yongli Ping

In this article, we study the expanding nature of universe in the contest of $f(R,L_m)$ gravity theory, here $ R $ represents the Ricci scalar and $ L_m $ is the matter Lagrangian density. With a specific form of $ f(R,L_m) $, we obtain the…

General Relativity and Quantum Cosmology · Physics 2023-06-28 J. K. Singh , Shaily , Ratbay Myrzakulov , Harshna Balhara

We solve the field equations of modified gravity for $f(R)$ model in metric formalism. Further, we obtain the fixed points of the dynamical system in phase space analysis of $f(R)$ models, both with and without the effects of radiation.…

General Relativity and Quantum Cosmology · Physics 2018-01-26 Murli Manohar Verma , Bal Krishna Yadav

In this paper, we present the cosmological scenario obtained from $f(R,T)$ gravity by using an exponential dependence on the trace of the energy-momentum tensor. With a numerical approach applied to the equations of motion, we show several…

General Relativity and Quantum Cosmology · Physics 2019-11-11 G. Ribeiro , R. Sfair , P. H. R. S. Moraes , J. R. L. Santos , A. de Souza Dutra

This paper examines the late-time accelerating Universe and the formation of large-scale structures within the modified symmetric teleparallel gravity framework, specifically using the $f(Q)$-gravity model, in light of recent cosmological…

General Relativity and Quantum Cosmology · Physics 2024-12-31 Shambel Sahlu , Amare Abebe

Not much by themselves, aparently. We try to reconstruct the scale factor $a(t)$ of the universe from the SNe Ia data, i.e. the luminosity distance $d_{L}(z)$, using only the cosmological principle and the assumption that gravitation is…

General Relativity and Quantum Cosmology · Physics 2017-06-19 İbrahim Semiz , A. Kazım Çamlıbel

This article presents a simple model that reproduces key concepts of modern cosmology within the framework of special relativity, at a level that is suitable for an undergraduate or high school setting. The model includes cosmic expansion…

General Relativity and Quantum Cosmology · Physics 2019-01-14 Markus Pössel

We present an application to cosmological models in $f({\cal R})$ theories within the Palatini formalism of a method that combines cosmography and the explicit form of the field equations in the calculation of the redshift drift. The method…

General Relativity and Quantum Cosmology · Physics 2019-03-28 F. A. Teppa Pannia , S. E. Perez Bergliaffa , N. Manske

Constraining the dark energy deceleration parameter is one of the fascinating topics in the recent cosmological paradigm. This work aims to reconstruct the dark energy using parametrization of the deceleration parameter in a flat FRW…

General Relativity and Quantum Cosmology · Physics 2023-09-26 Amine Bouali , Himanshu Chaudhary , Ujjal Debnath , Alok Sardar , G. Mustafa

We use a combination of observational data in order to reconstruct the free function of f(T) gravity in a model-independent manner. Starting from the data-driven determined dark-energy equation-of-state parameter we are able to reconstruct…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-20 Xin Ren , Thomas Hong Tsun Wong , Yi-Fu Cai , Emmanuel N. Saridakis

In this paper, we consider a comprehensive investigation of the cosmological model described by $f(R,T) = R + 2\lambda T$ (where $\lambda$ represents a free parameter) in light of the most recent observational data. By constraining the…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-29 N. Myrzakulov , M. Koussour , Alnadhief H. A. Alfedeel , E. I. Hassan

We explore recent estimations of the Hubble parameter $H$ depending on redshift $z$, which include 31 $H(z)$ data points measured from differential ages of galaxies and 26 data points, obtained with other methods. We describe these data…

General Relativity and Quantum Cosmology · Physics 2018-07-20 G. S. Sharov , V. O. Vasiliev

We investigate the Hubble constant tension within $f(R)$ modified gravity in the Jordan frame, focusing on its application to the dynamics of an isotropic Universe. A scalar field, non-minimally coupled to the metric, provides an extra…

General Relativity and Quantum Cosmology · Physics 2024-11-07 Tiziano Schiavone , Giovanni Montani

Many schemes have been proposed to perform a model-independent constraint on cosmological dynamics, such as nonparametric dark energy equation of state (EoS) \omega(z) or the deceleration parameter q(z). These methods usually contain…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-04 De-Zi Liu , Shuo Yuan , Yu Lu , Tong-Jie Zhang

The Hubble parameter $H(z)$ is directly related to the expansion of our Universe. It can be used to study dark energy and constrain cosmology models. In this paper, we propose that $H(z)$ can be measured using fast radio bursts (FRBs) with…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-27 Q. Wu , Hai Yu , F. Y. Wang