Dynamics of a quintom dark energy model non-minimally coupled with a mixed kinetic geometric term

2020 ◽  
Author(s):  
Mihai Marciu
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Field Equations ◽  
Distant Future ◽  
Phantom Divide ◽  
Phantom Divide Line ◽  
Big Crunch ◽  
The Universe

Within this work, a new dark energy model it is proposed, by taking into account a non-minimally mixed kinetic geometric coupling between the two fields which construct a quintom model. By considering numerical analysis of the corresponding field equations, the evolution of the Universe in the present model has been analyzed, taking into account different viable potentials. For exponential potentials, the model presents an accelerated expansion, and the dark energy equation of state exhibit the phantom divide line crossing. However, for a steeper potential, in the case of a mixed potential, it is observed that the Universe can manifest Big Crunch singularities in the distant future, and the moment for which the singularity occur is sensitive to the value of the mixed coupling strength embedded into the η coeffcient. The results show that an increase of the $\eta$ parameter determine a delay in the the Big Crunch time in the distant future. In the present context, the choice of the potential function play a fundamental role in the evolution of the dynamical system, leading to very distinct cosmological scenarios.

Ghost dark energy models in Bianchi I cosmologies with modified gravity

2014 ◽  
Vol 92 (2) ◽  
pp. 168-172 ◽  
Author(s):  
V. Fayaz ◽  
H. Hossienkhani ◽  
A. Aghamohammadi ◽  
M. Amirabadi
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
General Scheme ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Type I ◽  
Field Equations ◽  
Ghost Dark Energy ◽  
Expansion Of The Universe ◽  
The Universe

A ghost dark energy model has been recently put forward to explain the current accelerated expansion of the universe. In this model, we develop the general scheme for modified f(R) gravity reconstruction from realistic anisotropic Bianchi type I cosmology. Power-law volumetric expansion is used to obtain exact solutions of the field equations. We discuss the physical behavior of the solutions and anisotropy behavior of the fluid, the expansion parameter, and the model in future evolution of the universe. We reconstruct corresponding f(R) gravities and obtain the equation of state parameter. We show that the corresponding f(R) gravity of the ghost dark energy model can behave like phantom or quintessence of the selected models that describe accelerated expansion of the universe.

scholarly journals Thermodynamics of the viscous f(T,B) gravity in the new agegraphic dark energy model

2020 ◽  
Vol 35 (20) ◽  
pp. 2050166 ◽  
Author(s):  
A. Pourbagher ◽  
Alireza Amani
Keyword(s):  
Dark Energy ◽  
Hubble Parameter ◽  
Dark Energy Model ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
The Universe

In this paper, we first obtain the energy density by the approach of the new agegraphic dark energy model, and then the [Formula: see text] gravity model is studied as an alternative to the dark energy in a viscous fluid by flat-FRW background, in which [Formula: see text] and [Formula: see text] are torsion scalar and boundary term. The Friedmann equations will be obtained in the framework of modified teleparallel gravity by tetrad components. We consider that the universe dominates with components such as matter and dark energy by an interacting model. The Hubble parameter is parameterized by the power-law for the scale factor, and then we fit the corresponding Hubble parameter with observational data constraints. The variation of the equation of state (EoS) for dark energy is plotted as a function of the redshift parameter, and the accelerated expansion of the universe is explored. In what follows, the stability of the model is also studied on the base of the sound speed parameter. Finally, the generalized second law of thermodynamics is investigated by entropies of inside and on the boundary of the apparent horizon in thermodynamics equilibrium.

Generalized interaction term inspired dark energy model in fractal universe

2020 ◽  
Vol 35 (15) ◽  
pp. 2050126
Author(s):  
Abdul Jawad ◽  
Saba Qummer ◽  
Shamaila Rani ◽  
M. Younas
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Energy Model ◽  
Linear Term ◽  
Accelerated Expansion ◽  
Linear Interaction ◽  
Interaction Term ◽  
The Universe

By assuming generalized nonlinear and linear interaction term between dark matter and dark energy, we investigate the cosmic accelerated expansion of the universe. For this reason, we suppose a flat fractal universe platform as well as Tsallis holographic dark energy model. The Hubble horizon is being adopted as an infrared cutoff and extracted different cosmological parameters as well as plane. It is observed that equation-of-state parameter exhibits the quintom-like nature while ([Formula: see text]–[Formula: see text]) lies in thawing and freezing regions for different parametric values for both the cases. Furthermore, the squared sound speed shows stable behavior for nonlinear interaction term but shows the partially stable behavior for linear term. For both cases, the deceleration parameter leads to the accelerated phase of the universe and the consequences are comparable with observational data. The results for [Formula: see text]–[Formula: see text] plane, leads to the quintessence and phantom region of the universe for nonlinear case while this plane represents the Chaplygin gas behavior for linear term. The [Formula: see text] diagnostic also shows the satisfying results.

scholarly journals Barrow HDE model for statefinder diagnostic in FLRW universe

2021 ◽  
pp. 2150030
Author(s):  
Anirudh Pradhan ◽  
Archana Dixit ◽  
Vinod Kumar Bhardwaj
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Density Parameter ◽  
Phantom Divide ◽  
Phantom Divide Line ◽  
Expansion Of The Universe ◽  
Flrw Universe ◽  
The Universe

We have analyzed the Barrow holographic dark energy (BHDE) in the framework of flat FLRW universe by considering the various estimations of Barrow exponent △. Here, we define BHDE, by applying the usual holographic principle at a cosmological system, for utilizing the Barrow entropy rather than the standard Bekenstein–Hawking. To understand the recent accelerated expansion of the universe, consider the Hubble horizon as the IR cutoff. The cosmological parameters, especially the density parameter [Formula: see text], the equation of the state parameter [Formula: see text], energy density [Formula: see text] and the deceleration parameter [Formula: see text] are studied in this paper and found the satisfactory behaviors. Moreover we additionally focus on the two geometric diagnostics, the statefinder [Formula: see text] and [Formula: see text] to discriminant BHDE model from the [Formula: see text]CDM model. Here we determined and plotted the trajectories of evolution for statefinder [Formula: see text], [Formula: see text] and [Formula: see text] diagnostic plane to understand the geometrical behavior of the BHDE model by utilizing Planck 2018 observational information. Finally, we have explored the new Barrow exponent △, which strongly affects the dark energy equation of state that can lead it to lie in the quintessence regime, phantom regime and exhibits the phantom-divide line during the cosmological evolution.

Theoretical constraints on kinetic k-essence dark energy model in El-Nabulsi fractional action cosmology

2013 ◽  
Vol 91 (10) ◽  
pp. 844-849 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Scalar Field ◽  
Dark Energy Model ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Kinetic Term ◽  
Phantom Divide ◽  
Fractional Action Cosmology ◽  
Present Universe ◽  
Phantom Divide Line ◽  
The Universe

In this work, we considered an effective scalar field theory described by a Lagrangian with a noncanonical kinetic term, which leads to accelerated expansion in the present Universe and is known as k-essence in the framework of the fractional action cosmology recently introduced by El-Nabulsi. We have chosen a particular ansatz for the scale factor and the scalar field, in which both are described as a power-law of the time, t. We have studied the behavior of some cosmological quantities in other models to obtain some useful information about the model considered. We observed that the equation of state parameter, w, has decreasing behavior and it never crosses the phantom divide line (i.e., w = –1). Studying the statefinder pair {r, s} and {w, w′}, we observed that the model considered is able to obtain the ΛCDM phase of the Universe.

Tsallis holographic dark energy with hybrid expansion law

2020 ◽  
Vol 17 (11) ◽  
pp. 2050144 ◽  
Author(s):  
Vandna Srivastava ◽  
Umesh Kumar Sharma
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Accelerated Expansion ◽  
Eos Parameter ◽  
Phantom Divide ◽  
Accelerating Expansion ◽  
Phantom Divide Line ◽  
Phantom Scalar ◽  
The Rich ◽  
The Universe

In this work, we explore the Tsallis holographic dark energy (THDE) model with IR cutoff as Granda–Oliveros horizon describing the Universe experiencing an accelerating expansion phase in the framework of flat Friedmann–Lemaître–Robertson–Walker (FLRW) Universe. The Universe evolution from earlier decelerated to the current accelerated phase is exhibited by the deceleration parameter acquired in the THDE model. By the value of the Tsallis parameter [Formula: see text], the equation of state (EoS) parameter for the THDE model represents the rich behavior of the Cosmos as, the quintessence era ([Formula: see text]), crossing the phantom divide line and phantom era ([Formula: see text]). The squared sound speed [Formula: see text] also suggests that the THDE model is classically stable at present. Also, the correspondence with the quintessence and phantom scalar field for the THDE model is analyzed to describe the accelerated expansion of the Universe.

scholarly journals A modified holographic Ricci dark energy model in a self-creation cosmology

2016 ◽  
Vol 94 (12) ◽  
pp. 1314-1318 ◽  
Author(s):  
M.P.V.V. Bhaskara Rao ◽  
D.R.K. Reddy ◽  
K. Sobhan Babu
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Bianchi Type ◽  
Energy Model ◽  
Smooth Transition ◽  
Type Ii ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Theory Of Gravitation ◽  
The Universe

This paper deals with a locally rotationally symmetric Bianchi type II space–time with dark matter and anisotropic modified holographic Ricci dark energy as source in second self-creation theory of gravitation proposed by Barber (Gen. Relativ. Gravit. 14, 117 (1982)). To solve the field equations of this theory we have used (i) hybrid expansion law, (ii) a relation between metric potentials and a modified holographic Ricci dark energy given by Chen and Jing (Phys. Lett. B, 679, 144 (2009)). The solution obtained represents a Bianchi type II modified holographic dark energy model in self-creation cosmology. We observe that there is a smooth transition of the universe from decelerated phase to accelerated phase. This fact is in good agreement with the observations of modern cosmology. We have also discussed some important physical aspects of the model.

scholarly journals Amended FRW Metric and Rényi Dark Energy Model

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Sarfraz Ali ◽  
Sabir Iqbal ◽  
Khuram Ali Khan ◽  
Hamid Reza Moradi
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Modified Gravity ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Field Equations ◽  
First Case ◽  
Chern Simons ◽  
The Universe

This article is devoted to exploring the Rényi holographic dark energy model in the theory of Chern-Simons modified gravity. We studied the deceleration parameter, equation of state, and cosmological plane considering the Amended FRW modal. Modified field equations of -gravity theory gave two independent solutions. In the first case, this model provided the transitional change from deceleration to acceleration compatible with collected observational data. However, it supported a decelerating phase of expansion only in the second case. It was noted that the Equation of State advocated the dominance era under the influence of dark energy in the first case and the second predicted the influence of Λ CDM. In both cases, ω < 0 , ω ′ < 0 voted that the universe is in a freezing region and its cosmic expansion is more rapidly accelerated in the background of Chern-Simons modified gravity.

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