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We study mimetic $F(R)$ gravity with potential and Lagrange multiplier constraint. In the context of these theories, we introduce a reconstruction technique which enables us to realize arbitrary cosmologies, given the Hubble rate and an…

General Relativity and Quantum Cosmology · Physics 2016-02-17 S. D. Odintsov , V. K. Oikonomou

How do we appropriately fit a model based on an idealised Friedmann-Lema\^{}tre Robertson-Walker spacetime to observations made from a single location in a lumpy Universe? We address this question for surveys that measure the imprints of…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-24 Obinna Umeh

This research investigates the impact of modified gravity on cosmic scales, focusing on $f(Q)$ cosmology. By applying energy conditions, the study reconstructs various $f(Q)$ models, considering an accelerating Universe, quintessence, and a…

General Relativity and Quantum Cosmology · Physics 2025-04-14 Irfan Mahmood , Hira Sohail , Allah Ditta , S. H. Shekh , Anil Kumar Yadav

In the last few decades, extensions of General Relativity have reached always more attention especially in view of possible breakdowns of the standard $\Lambda$CDM paradigm at intermediate and high redshift regimes. If General Relativity…

General Relativity and Quantum Cosmology · Physics 2020-03-19 Marco Calzà , Alessandro Casalino , Orlando Luongo , Lorenzo Sebastiani

We show that modelling the universe as a pre-geometric system with emergent quantum modes, and then constructing the classical limit, we obtain a new account of space and gravity that goes beyond Newtonian gravity even in the…

General Physics · Physics 2007-09-20 Reginald T Cahill

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 a universe where, according to the standard cosmological models, some 97% of the total mass-energy is still "missing in action" it behooves us to spend at least a little effort critically assessing and exploring radical alternatives.…

General Relativity and Quantum Cosmology · Physics 2017-11-28 Matt Visser

In this study, we have explored a transitioning cosmological model of universe's expansion in $f(R,\mathcal{L}_{m})$ gravity. The quadratic type of equation of state parameter in the form $\omega=-1 + \alpha (1 + z) + \beta (1 + z)^2$,…

General Relativity and Quantum Cosmology · Physics 2025-04-16 Vinod Kumar Bhardwaj , Saibal Ray

We use the recently released cosmic chronometer data and the latest measured value of the local Hubble parameter, combined with the latest joint light curves of Supernovae Type Ia, and Baryon Acoustic Oscillation distance measurements, in…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-09 Rafael C. Nunes , Supriya Pan , Emmanuel N. Saridakis , Everton M. C. Abreu

Fractional cosmology modifies the standard derivative to Caputo's fractional derivative of order $\mu$, generating changes in General Relativity. Friedmann equations are modified, and the evolution of the species densities depends on $\mu$…

General Relativity and Quantum Cosmology · Physics 2022-10-26 Miguel A. García-Aspeitia , Guillermo Fernandez-Anaya , A. Hernández-Almada , Genly Leon , Juan Magaña

The standard relation between the cosmological redshift and cosmic scale factor underlies cosmological inference from virtually all kinds of cosmological observations, leading to the emergence of the LambdaCDM cosmological model. This…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-08 Radosław Wojtak , Francisco Prada

A local void in the globally Friedmann-Robertson-Walker cosmological model with the critical density ($\Omega_{0}=1$) is studied. The inhomogeneity is described using a Lema\^{\i}tre-Tolman-Bondi solution for a spherically symmetric…

Astrophysics · Physics 2008-02-03 J. W. Moffat , D. C. Tatarski

We perform three-dimensional numerical relativity simulations of homogeneous and inhomogeneous expanding spacetimes, with a view towards quantifying non-linear effects from cosmological inhomogeneities. We demonstrate fourth-order…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-22 Hayley J. Macpherson , Paul D. Lasky , Daniel J. Price

Our objective in this paper is to study the late-time behavior of the universe in a model resulting from a parametrization of the Hubble parameter ($H$) in $f(Q,T)$ gravity. We have considered the flat Friedmann-Lemaitre-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2023-04-19 Viraj Kalsariya , Shibesh Kumar Jas Pacif

We intend to study a new class of cosmological models in $f(R, T)$ modified theories of gravity, hence define the cosmological constant $\Lambda$ as a function of the trace of the stress energy-momentum-tensor $T$ and the Ricci scalar $R$,…

General Physics · Physics 2020-03-26 Safiqul Islam , Praveen Kumar , G. S. Khadekar , Tapas K Das

The problem of reproducing dark energy effects is reviewed here with particular interest devoted to cosmography. We summarize some of the most relevant cosmological models, based on the assumption that the corresponding barotropic equations…

General Relativity and Quantum Cosmology · Physics 2013-12-09 Salvatore Capozziello , Mariafelicia De Laurentis , Orlando Luongo , Alan Cosimo Ruggeri

The solution of the problem of describing the Friedmann observables (the Hubble law, the red shift, etc.) in quantum cosmology is proposed on the basis of the method of gaugeless Hamiltonian reduction in which the gravitational part of the…

General Relativity and Quantum Cosmology · Physics 2009-10-30 A. M. Khvedelidze , V. V. Papoyan , Yu. G. Palii , V. N. Pervushin

We consider a class of five-dimensional cosmological solutions which contains two arbitrary function $\mu(t)$ and $\nu(t)$. We found that the arbitrary function $\mu(t)$ contained in the solutions can be rewritten in terms of the redshift…

Astrophysics · Physics 2009-11-13 Lixin Xu , Hongya Liu , Chengwu Zhang

In this work we consider the realization of a variant emergent Universe scenario in the context of $f(R)$ gravity. We use well-known reconstruction techniques existing in the literature, and we find the approximate form of the vacuum $f(R)$…

General Relativity and Quantum Cosmology · Physics 2024-03-18 V. K. Oikonomou , Gregory K. Kafanelis

We investigate late-time cosmology in the context of modified $f(Q,L_m)$ gravity, considering a non-linear model$ f(Q,L_m) = \alpha Q + \beta L_m^n + \lambda$ where, $\alpha$, $\beta$, $\lambda$, and $n$ are some free parameters. The…

General Relativity and Quantum Cosmology · Physics 2026-01-16 Rajdeep Mazumdar , Kalyan Malakar , Kalyan Bhuyan