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We discuss the classical cosmological tests for a large class of FRW type models driven by a decaying vacuum energy density. Analytic expressions for the lookback time, age of the universe, luminosity distance, angular diameter, and galaxy…

Astrophysics · Physics 2009-11-07 J. V. Cunha , J. A. S. Lima , N. Pires

Assuming homogeneous isotropic Lambda-CDM cosmology allows Lambda, spatial curvature and dark matter density to be inferred from large scale structure observations such as supernovae. The purpose of this paper is to extend this to allow…

General Relativity and Quantum Cosmology · Physics 2011-02-02 Toby Wiseman , Benjamin Withers

The field equations in $f(R)$ gravity derived from the Palatini variational principle and formulated in the Einstein conformal frame yield a cosmological term which varies with time. Moreover, they break the conservation of the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Nikodem J. Poplawski

In this work, we consider an extension of symmetric teleparallel gravity, namely, $f(Q)$ gravity, where the fundamental block to describe spacetime is the nonmetricity, $Q$. Within this formulation of gravitation, we perform an…

General Relativity and Quantum Cosmology · Physics 2019-11-15 Ruth Lazkoz , Francisco S. N. Lobo , María Ortiz-Baños , Vincenzo Salzano

$f(Q)$ symmetric-teleparallel gravity is considered in view of Quantum Cosmology. Specifically, we derive cosmological equations for $f(Q)$ models and then investigate the related energy conditions. In the minisuperspace formalism, the…

General Relativity and Quantum Cosmology · Physics 2023-07-04 Francesco Bajardi , Salvatore Capozziello

Symmetric teleparallel gravity theories, in which the gravitational interaction is attributed to the nonmetricity of a flat, symmetric, but not metric-compatible affine connection, have been a topic of growing interest in recent studies.…

General Relativity and Quantum Cosmology · Physics 2022-01-03 Manuel Hohmann

Understanding the evolution of dark energy poses a significant challenge in modern cosmology, as it is responsible for the universe's accelerated expansion. In this study, we focus on a specific $f(T)$ cosmological model and analyze its…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-14 A. Zhadyranova , M. Koussour , S. Bekkhozhayev , V. Zhumabekova , J. Rayimbaev

We examine in this paper the possibility of finding exact solutions for Teleparallel Gravity (TG) of the type of spherically symmetric Lema\^\i tre-Tolman-Bondi (LTB) dust models. We apply to the LTB metric, as obtained from the…

General Relativity and Quantum Cosmology · Physics 2021-06-07 Sebastián Nájera , Aram Aguilar , Celia Escamilla-Rivera , Roberto A. Sussman

We study a model of Symmetric Teleparallel gravity that is able to account for the current accelerated expansion of the universe without the need for dark energy component. We investigate this model by making use of dynamical system…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-26 José Ferreira , Tiago Barreiro , José P. Mimoso , Nelson J. Nunes

We address some recent erroneous claim that $H_0$ observations are difficult to accommodate with LTB cosmological models, showing how to construct solutions in agreement with an arbitrary value of $H_0$ by re-writing the exact solution in…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-11 Antonio Enea Romano

In this study, we investigate signature flips within the framework of cosmological models featuring a time-varying vacuum energy term $\Lambda(t)$. Specifically, we consider the power-law form of $\Lambda=\alpha H^n$, where $\alpha$ and $n$…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-11 Yerlan Myrzakulov , M. Koussour , M. Karimov , J. Rayimbaev

In this work we consider a flat cosmological model with a set of fluids in the framework of supersymmetric cosmology. The obtained supersymmetric algebra allowed us to take quantum solutions. It is shown that only in the case of a…

General Relativity and Quantum Cosmology · Physics 2010-12-23 J. J. Rosales , V. I. Tkach

The $f(T)$ theory, which is an extension of teleparallel, or torsion scalar $T$, gravity, is recently proposed to explain the present cosmic accelerating expansion with no need of dark energy. In this Letter, we first perform the…

General Relativity and Quantum Cosmology · Physics 2010-10-12 Puxun Wu , Hongwei Yu

Considering the condition on conservation of energy momentum tensor (EMT), we study late time cosmological solutions in the context of $f(R,T)=R+\alpha T^{n}$ gravity (where $\alpha$ and $n$ are constants) in a flat FLRW spacetime. The…

General Relativity and Quantum Cosmology · Physics 2024-03-06 Hamid Shabani , Norman Cruz , Amir Hadi Ziaie

We study the dynamics of the FLRW flat cosmological models in which the vacuum energy varies with time, $\Lambda(t)$. In this model we find that the main cosmological functions such as the scale factor of the universe and the Hubble flow…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Spyros Basilakos

We extract observational constraints on $f(T)$ gravity, using the recently proposed statistical method which is not affected by the value of $H_0$ and thus it bypasses the problem of the disagreement in its exact numerical value between…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-15 S. Basilakos , S. Nesseris , F. K. Anagnostopoulos , E. N. Saridakis

In this work, we investigate a cosmological scenario with a time-dependent cosmological constant $\Lambda$(t) within the spatially flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) framework. Here we study a power-law $\Lambda(t)$CDM model…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Archana Dixit , Manish Yadav , Anirudh Pradhan , M. S. Barak

This work examines the cosmological implications of two functional forms of $f(R,T) = R + \alpha T^n$ gravity: for two different value of $n $ where $n=1$ and $n\neq 1$, and $\alpha$ and $n$ are free parameters. The modified Friedmann…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-24 Mustapha Lamaaoune

For the fourth-order teleparallel $f\left(T,B\right) $ theory of gravity, we investigate the cosmological evolution for the universe in the case of a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker background space. We focus on…

General Relativity and Quantum Cosmology · Physics 2021-06-03 Andronikos Paliathanasis , Genly Leon

We present a unified dark energy framework capable of generating a continuous spectrum of cosmological ``rip'' scenarios -- including the Big Rip, Grand Rip, Mild Rip, Little Rip, Little Sibling of the Big Rip, and the newly found Dollhouse…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-05 Mikel Artola , Ruth Lazkoz , Vincenzo Salzano