Exact solutions and constraints on the dark energy model in FRW Universe

2021 ◽  
Vol 42 (2) ◽  
Author(s):  
Albin Joseph ◽  
Rajib Saha
Keyword(s):  
Dark Energy ◽  
Exact Solutions ◽  
Dark Energy Model ◽  
Energy Model ◽  
Frw Universe

scholarly journals HOLOGRAPHIC DARK ENERGY MODEL CHARACTERIZED BY THE CONFORMAL-AGE-LIKE LENGTH

2012 ◽  
Vol 27 (16) ◽  
pp. 1250085 ◽  
Author(s):  
ZHUO-PENG HUANG ◽  
YUE-LIANG WU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Dimensional Space ◽  
Early Time ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
Frw Universe

A holographic dark energy model characterized by the conformal-age-like length scale [Formula: see text] is motivated from the four-dimensional space–time volume at cosmic time t in the flat Friedmann–Robertson–Walker (FRW) universe. It is shown that when the background constituent with constant equation of state wm dominates the universe in the early time, the fractional energy density of the dark energy scales as [Formula: see text] with the equation of state given by [Formula: see text]. The value of wm is taken to be wm≃-1 during inflation, wm = ⅓ in radiation-dominated epoch and wm = 0 in matter-dominated epoch, respectively. When the model parameter d takes the normal value at order one, the fractional density of dark energy is naturally negligible in the early universe, Ω de ≪1 at a ≪1. With such an analytic feature, the model can be regarded as a single-parameter model like the ΛCDM model, so that the present fractional energy density Ω de (a = 1) can solely be determined by solving the differential equation of Ωde once d is given. We further extend the model to the general case in which both matter and radiation are present. The scenario involving possible interaction between the dark energy and the background constituent is also discussed.

FRW UNIVERSE WITH GENERALIZED GHOST DARK ENERGY MODEL

2021 ◽  
Vol 10 (4) ◽  
pp. 1997-2004
Author(s):  
D. Raut ◽  
G.S. Khadekar ◽  
A. Ghogre
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Frw Universe ◽  
Ghost Dark Energy ◽  
Generalized Ghost Dark Energy

scholarly journals Reconstruction of the New Agegraphic Polytropic Gas Dark Energy Model in the Flat Friedmann Robertson Walker (FRW) Universe

2021 ◽  
Vol 13 (3) ◽  
pp. 779-784
Author(s):  
P. Das ◽  
K. P. Singh
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Scalar Fields ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Frw Universe ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Polytropic Gas ◽  
Friedmann Robertson Walker

In this paper, we study the Polytropic Gas Dark Energy model and New Agegraphic Dark Energy model in the flat Friedmann Robertson Walker (FRW) Universe and establish a correspondence between them for the scalar fields. This correspondence allows reconstructing the potential of the Polytropic Gas scalar fields and dynamics of the scalar fields according to the evolutions of the New Agegraphic Dark Energy, which describes the accelerated expansion of the Universe.

Cosmic evolution of ghost dark energy models in f(G,T) gravity

2019 ◽  
Vol 35 (10) ◽  
pp. 2050063
Author(s):  
M. Sharif ◽  
Saadia Saba
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Speed Of Sound ◽  
Dark Energy Model ◽  
State Parameter ◽  
Energy Model ◽  
Frw Universe ◽  
Ghost Dark Energy ◽  
Energy Models ◽  
Generalized Ghost Dark Energy

The aim of this paper is to study the reconstruction paradigm for both ghost as well as generalized ghost dark energy models in the context of [Formula: see text] gravity. To accomplish this, we use correspondence scenario for pressureless flat FRW universe with power-law scale factor. The cosmological behavior of reconstructed models is analyzed through graphical analysis of deceleration, equation of state, squared speed of sound parameters and phase planes. It is found that the deceleration parameter represents accelerated epoch for both models whereas equation of state parameter indicates phantom era of the universe for ghost dark energy model and quintessence for its generalized version. The phase planes [Formula: see text] and [Formula: see text] indicate the freezing region with phantom phase for both reconstructed dark energy models. We conclude that the squared speed of sound parameter leads to the stability of generalized ghost dark energy model only.

scholarly journals An interacting new holographic dark energy model: Observational constraints

2019 ◽  
Vol 28 (12) ◽  
pp. 1950152 ◽  
Author(s):  
Ehsan Sadri ◽  
Martiros Khurshudyan
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Observational Data ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Current Model ◽  
Energy Model ◽  
Late Time ◽  
Holographic Dark Energy Model ◽  
Frw Universe

In this paper, we study an interacting new holographic dark energy model (NHDE) in DGP braneworld with a spatially flat FRW universe. Mainly, in this study we concentrate our attention on both interacting and noninteracting forms of the model. The study shows that the equation of state and the deceleration parameter depict an accelerated universe for all variety of interactions. On the other hand, the StateFinder analysis shows that the interacting and noninteracting behave similar to both quintessence and phantom dark energy and for the present value obey the behavior of quintessence. Moreover, the result of [Formula: see text]-diagnostic emphasizes on the result of the equation of state showing that the current model in high–[Formula: see text] stays in the quintessence era and in the late time has the Phantom-like behavior. By the use of the squared sound speed [Formula: see text] we find that the present mode has a good stability. In order to obtain the best fit values of the parameters in this work, we used the latest observational data (Pantheon, Boss DR12 and Planck 2015) implementing MCMC method by the use of EMCEE python package. We also employ AkaikeInformation Criterion (AIC) and Bayesian Information Criterion (BIC) model selection tools and comparethe model with both [Formula: see text]CDM and holographic Ricci dark energy as the reference models. We observe that the evidence against the interacting and noninteracting NHDE with consideration of both references is strongly positive and BIC rules out the NHDE model. Generally, the results of AIC and BIC state that the observational data do not favor the NHDE model.

scholarly journals INSTABILITY OF QCD GHOST DARK ENERGY MODEL

2011 ◽  
Vol 20 (12) ◽  
pp. 2369-2381 ◽  
Author(s):  
ESMAEIL EBRAHIMI ◽  
AHMAD SHEYKHI
Keyword(s):  
Dark Energy ◽  
Perfect Fluid ◽  
Sound Speed ◽  
Dark Energy Model ◽  
Coupling Parameter ◽  
Energy Model ◽  
Frw Universe ◽  
Ghost Dark Energy ◽  
The Stability ◽  
Qcd Ghost Dark Energy

We investigate the instability of the ghost dark energy model against perturbations in different cases. To this goal we use the squared sound speed [Formula: see text] whose sign determines the stability of the model. When [Formula: see text] the model is unstable against perturbation. At first we discuss the noninteracting ghost dark energy model in a flat FRW universe and find out that such a model is unstable due to the negativity of the [Formula: see text] in all epoches. The interacting ghost dark energy model in both flat and nonflat universe are studied in the next parts and in both cases we find that the squared sound speed of ghost dark energy is always negative. This implies that the perfect fluid for ghost dark energy is classically unstable against perturbations. In both flat and non flat cases we find that the instability of the model increases with increasing the value of the interacting coupling parameter.

scholarly journals Cosmological viable f(R,T) dark energy model: dynamics and stability

2014 ◽  
Vol 356 (1) ◽  
pp. 173-180 ◽  
Author(s):  
E. H. Baffou ◽  
A. V. Kpadonou ◽  
M. E. Rodrigues ◽  
M. J. S. Houndjo ◽  
J. Tossa
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Model Dynamics
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