Cosmic acceleration and stability of cosmological models in extended teleparallel gravity

Pramana ◽  
2021 ◽  
Vol 95 (1) ◽  
Author(s):  
A Y Shaikh ◽  
S V Gore ◽  
S D Katore
Keyword(s):  
Teleparallel Gravity ◽  
Cosmological Models ◽  
Cosmic Acceleration

scholarly journals Anisotropic cosmological reconstruction in f(R, T) gravity

2018 ◽  
Vol 33 (29) ◽  
pp. 1850170 ◽  
Author(s):  
B. Mishra ◽  
Sankarsan Tarai ◽  
S. K. Tripathy
Keyword(s):  
Simple Approach ◽  
Cosmological Models ◽  
Gravity Theory ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Coupling Constant ◽  
Anisotropic Cosmological Models

Anisotropic cosmological models are constructed in f(R, T) gravity theory to investigate the dynamics of universe concerning the late time cosmic acceleration. Using a more general and simple approach, the effect of the coupling constant and anisotropy on the cosmic dynamics have been investigated. In this study, it is found that cosmic anisotropy substantially affects cosmic dynamics.

A probe of cosmological models in modified teleparallel gravity

2021 ◽  
pp. 2150208
Author(s):  
Archana Dixit ◽  
Anirudh Pradhan ◽  
Dinesh Chandra Maurya
Keyword(s):  
Hubble Constant ◽  
Teleparallel Gravity ◽  
Cosmological Term ◽  
Cosmological Models ◽  
Model Parameters ◽  
Late Time ◽  
General Function ◽  
Eos Parameter ◽  
Variable Cosmological Term ◽  
Present Universe

In this paper, we have investigated the physical behavior of cosmological models in modified Teleparallel gravity with a general function [Formula: see text] where [Formula: see text] and [Formula: see text] are model parameters and [Formula: see text] is the torsion scalar. We have considered a homogeneous and isotropic Friedman universe filled with perfect fluid. We have derived the deceleration parameter [Formula: see text] in terms of equation of state (EoS) parameter [Formula: see text] and Hubble parameter [Formula: see text]. We have investigated the variation of [Formula: see text] over the observed values of Hubble constant in various observations within the range of redshift [Formula: see text]. Also, we have studied effective energy density [Formula: see text], effective pressure [Formula: see text] and effective EoS parameter [Formula: see text]. We have observed that the second term of [Formula: see text] function behaves just like variable cosmological term [Formula: see text] ([Formula: see text]) at late-time universe and causes the acceleration in expansion and works just like dark energy candidates. Also, we have evaluated the age of the present universe for various stages of matter [Formula: see text] and various [Formula: see text] functions.

scholarly journals The k-essence models and cosmic acceleration in generalized teleparallel gravity

2011 ◽  
Vol 84 (5) ◽  
pp. 055005 ◽  
Author(s):  
M Sharif ◽  
Shamaila Rani
Keyword(s):  
Teleparallel Gravity ◽  
Cosmic Acceleration

scholarly journals THE GRAVITATIONAL ENERGY PROBLEM FOR COSMOLOGICAL MODELS IN TELEPARALLEL GRAVITY

2010 ◽  
Vol 19 (12) ◽  
pp. 1925-1935 ◽  
Author(s):  
S. C. ULHOA ◽  
J. F. DA ROCHA NETO ◽  
J. W. MALUF
Keyword(s):  
Average Energy ◽  
Teleparallel Gravity ◽  
Space Time ◽  
Gravitational Energy ◽  
Cosmological Models ◽  
De Sitter ◽  
Energy Problem ◽  
First Case ◽  
Einstein's Equation ◽  
Average Energy Density

We present a method to calculate the gravitational energy when asymptotic boundary conditions for the space–time are not given. This is the situation for most of the cosmological models. The expression for the gravitational energy is obtained in the context of the teleparallel equivalent of general relativity. We apply our method first to the Schwarzschild–de Sitter solution of Einstein's equation, and then to the Robertson–Walker universe. We show that in the first case our method leads to an average energy density of the vacuum space–time, and in the latter case the energy vanishes in the case of null curvature.

scholarly journals Cosmological dynamics of dark energy in scalar-torsion $$f(T,\phi )$$ gravity

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Manuel Gonzalez-Espinoza ◽  
Giovanni Otalora
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Autonomous System ◽  
Saddle Points ◽  
Teleparallel Gravity ◽  
Cosmic Acceleration ◽  
Accelerated Expansion ◽  
Fluid Density ◽  
Exponential Potential ◽  
The Stability

AbstractIt is investigated the cosmological dynamics of scalar-torsion $$f(T,\phi )$$ f ( T , ϕ ) gravity as a dark energy model, where T is the torsion scalar of teleparallel gravity and $$\phi $$ ϕ is a canonical scalar field. In this context, we are concerned with the phenomenology of the class of models with non-linear coupling to gravity and exponential potential. We obtain the critical points of the autonomous system, along with the stability conditions of each one of them and their cosmological properties. Particularly, we show the existence of new attractors with accelerated expansion, as well as, new scaling solutions in which the energy density of dark energy scales as the background fluid density, thus, defining the so-called scaling radiation and scaling matter epochs. The scaling solutions are saddle points, and therefore, the system exits these solutions to the current epoch of cosmic acceleration, towards an attractor point describing the dark energy-dominated era.

scholarly journals Rip cosmological models in extended symmetric teleparallel gravity

2021 ◽  
pp. 100925
Author(s):  
Laxmipriya Pati ◽  
S.A. Kadam ◽  
S.K. Tripathy ◽  
B. Mishra
Keyword(s):  
Teleparallel Gravity ◽  
Cosmological Models

Locally rotationally symmetric Bianchi type-I string cosmological models in f(R) theory of gravity

2018 ◽  
Vol 15 (09) ◽  
pp. 1850156 ◽  
Author(s):  
Y. Aditya ◽  
D. R. K. Reddy
Keyword(s):  
Bianchi Type ◽  
Scalar Fields ◽  
Cosmological Models ◽  
Cosmic Acceleration ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Locally Rotationally Symmetric ◽  
Rotationally Symmetric ◽  
Theory Of Gravity

This study deals with spatially homogeneous and anisotropic locally rotationally symmetric (LRS) Bianchi type-I universe with cosmic string source in the framework of [Formula: see text] theory of gravity [S. Capozziello, S. Carloni and A. Troisi, Quintessence without scalar fields, Recent Res. Dev. Astron. Astrophys. 1 (2003), 625; S. Nojiri and S. D. Odintsov, Modified gravity with negative and positive powers of curvature: Unification of inflation and cosmic acceleration, Phys. Rev. D 68 (2003) 123512]. Solving the field equations using (i) relation between metric potentials, (ii) power law relation between [Formula: see text] and average scale factor [Formula: see text] and (iii) equations of state for string models we have presented Takabayasi [T. Takabayasi, Quantum Mechanics Determinism, Causality, and Particles (Springer, Berlin, 1976)], Nambu [P. S. Letelier, String cosmologies, Phys. Rev. D 28 (1983) 2414–2419] and Reddy [D. R. K. Reddy, A string cosmological model in a scalar–Tensor theory of gravitation, Astrophys. Space Sci. 286 (2003) 359–363] string cosmological models. The dynamical parameters of our models are determined and their physical behavior is discussed. The most interesting result about the models is that the anisotropic effects are wiped out at late times.

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