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.

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.

scholarly journals The influence of the dark energy model in the Roche potential for interacting galaxies

2020 ◽  
pp. 127-130
Author(s):  
U.N. Zakirov ◽  
Keyword(s):  
Dark Energy ◽  
Equivalence Principle ◽  
Dark Energy Model ◽  
Energy Model ◽  
Interacting Galaxies ◽  
Vacuum Field ◽  
Accelerated Expansion ◽  
Expansion Of The Universe ◽  
First Time ◽  
The Universe

For the first time, the influence of the dark energy model - a new non-vacuum field - in the generalized (with allowance for the equivalence principle) Roche potential for interacting galaxies was considered. The equation of thermodynamics of the mentioned field and its possible evolutions affecting on the accelerated expansion of the Universe is given.

Interacting new holographic dark energy model with varying G in nonflat universe

2013 ◽  
Vol 91 (12) ◽  
pp. 1090-1092
Author(s):  
V. Fayaz ◽  
F. Felegary ◽  
H. Hossienkhani
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Late Time ◽  
Holographic Dark Energy Model ◽  
Expansion Of The Universe ◽  
The Universe

Motivated by the work of Karami and Fehri (Phys. Lett. B, 684, 61 (2010)). We generalize their work with varying G. We investigate the new holographic dark energy model with varying G. We consider a spatially nonflat universe containing interacting new holographic dark energy with pressureless dark matter. We obtain the equation of state and the deceleration parameters. Also we reconstruct ωA for a = a0tn and H = [β/(α − 1)](1/t) in the late time universe. We also obtain q for a = a0tn and H = [β/(α − 1)](1/t) in the present time universe, which describes accelerated expansion of the universe.

Constraints on the Ricci dark energy cosmologies in Bianchi type I model

2021 ◽  
pp. 2150095
Author(s):  
H. Hossienkhani ◽  
N. Azimi ◽  
H. Yousefi
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Bianchi Type ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Likelihood Method ◽  
Type I ◽  
Ricci Dark Energy ◽  
Bianchi Type I ◽  
The Impact

The impact of anisotropy on the Ricci dark energy cosmologies is investigated where it is assumed that the geometry of the universe is described by Bianchi type I (BI) metric. The main goal is to determine the astrophysical constraints on the model by using the current available data as type Ia supernovae (SNIa), the Baryon Acoustic Oscillation (BAO), and the Hubble parameter [Formula: see text] data. In this regard, a maximum likelihood method is applied to constrain the cosmological parameters. Combining the data, it is found out that the allowed range for the density parameter of the model stands in [Formula: see text]. With the help of the Supernova Legacy Survey (SNLS) sample, we estimate the possible dipole anisotropy of the Ricci dark energy model. Then, by using a standard [Formula: see text] minimization method, it is realized that the transition epoch from early decelerated to current accelerated expansion occurs faster in Ricci dark energy model than [Formula: see text]CDM model. The results indicate that the BI model for the Ricci dark energy is consistent with the observational data.

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.

scholarly journals PRESENT ACCELERATION OF THE UNIVERSE, HOLOGRAPHIC ENERGY AND BRANS–DICKE THEORY

2009 ◽  
Vol 24 (22) ◽  
pp. 1785-1792 ◽  
Author(s):  
B. NAYAK ◽  
L. P. SINGH
Keyword(s):  
Dark Energy ◽  
Power Law ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Accelerated Expansion ◽  
Temporal Behavior ◽  
Holographic Dark Energy Model ◽  
Acceleration Of The Universe ◽  
Expansion Of The Universe ◽  
The Universe

The present-day accelerated expansion of the universe is naturally addressed within the Brans–Dicke theory just by using holographic dark energy model with inverse of Hubble scale as IR cutoff and power law temporal behavior of scale factor. It is also concluded that if the universe continues to expand, then one day it might be completely filled with dark energy.

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 COSMOGRAPHY OF INTERACTING GENERALIZED QCD GHOST DARK ENERGY

2013 ◽  
Vol 22 (14) ◽  
pp. 1350084 ◽  
Author(s):  
MOHAMMAD MALEKJANI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Accelerated Expansion ◽  
Model Parameter ◽  
Ghost Dark Energy ◽  
Evolutionary Trajectories ◽  
Expansion Of The Universe ◽  
Qcd Ghost Dark Energy ◽  
The Universe ◽  
Friedmann Robertson Walker

Exploring the accelerated expansion of the universe, we investigate the generalized ghost dark energy (GGDE) model from the statefinder diagnostic analysis in a flat Friedmann–Robertson–Walker universe. First, we calculate the cosmological evolution and statefinder trajectories for noninteracting case and then extend this work by considering the interaction between dark matter and dark energy components. We show that in the noninteracting case the phantom line cannot be crossed and also the evolutionary trajectories of model in s - r plane cannot be discriminated. It has been shown that the present location of model in s - r plane would be close to observational value for negative values of the model parameter. In the presence of interaction between dark matter and dark energy, the phantom regime is achieved, the accelerated phase of expansion occurs sooner compared with the noninteracting case. The GGDE model is also discussed from the viewpoint of perturbation theory by calculating the adiabatic sound speed of the model. Finally, unlike the noninteracting case, the evolutionary trajectories in s - r plane can be discriminated in the interacting model. Like the noninteracting model, in the interacting case the present location of GGDE model is closer to observational value for negative values of the model parameter.

scholarly journals RECONSTRUCTION OF MODIFIED GRAVITY WITH GHOST DARK ENERGY MODELS

2012 ◽  
Vol 27 (18) ◽  
pp. 1250100 ◽  
Author(s):  
A. KHODAM-MOHAMMADI ◽  
M. MALEKJANI ◽  
M. MONSHIZADEH
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Modified Gravity ◽  
Deceleration Parameter ◽  
Accelerated Expansion ◽  
Ghost Dark Energy ◽  
Energy Models ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Generalized Ghost Dark Energy

In this work, we reconstruct the f(R) modified gravity for different ghost and generalized-ghost dark energy (DE) models in FRW flat universe, which describes the accelerated expansion of the universe. The equation of state and deceleration parameter of reconstructed f(R) gravity have been calculated. The equation of state and deceleration parameter of reconstructed f(R)-ghost/generalized-ghost DE, have been calculated. We show that the corresponding f(R) gravity of ghost/generalized-ghost DE model can behave like phantom or quintessence. Also the transition between deceleration to acceleration regime is indicated by deceleration parameter diagram for reconstructed f(R) generalized-ghost DE model.

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