Dark energy model in higher-dimensional FRW universe with respect to generalized entropy of Sharma and Mittal of flat FRW space–time

2019 ◽  
Vol 97 (11) ◽  
pp. 1185-1186 ◽  
Author(s):  
E.C. Gunay Demirel
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
State Parameter ◽  
Space Time ◽  
Observational Evidence ◽  
The State ◽  
Frw Universe ◽  
Generalized Entropy ◽  
Higher Dimensional ◽  
Friedmann Robertson Walker

In this study, we report the state parameter of dark energy in higher dimensional Friedmann–Robertson–Walker (FRW) space–time according to generalized entropy of Sharma and Mittal. In this case we analyze the state parameter of dark energy according to today’s observational evidence.

scholarly journals Thermodynamics of Ricci-Gauss-Bonnet Dark Energy

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Ayesha Iqbal ◽  
Abdul Jawad
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Cold Dark Matter ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Frw Universe ◽  
Thermodynamical Equilibrium ◽  
Event Horizons ◽  
Generalized Second Law ◽  
Friedmann Robertson Walker

We investigate the validity of generalized second law of thermodynamics of a physical system comprising newly proposed dark energy model called Ricci-Gauss-Bonnet and cold dark matter enveloped by apparent horizon and event horizon in flat Friedmann-Robertson-Walker (FRW) universe. For this purpose, Bekenstein entropy, Renyi entropy, logarithmic entropy, and power law entropic corrections are used. It is found that this law exhibits the validity on both apparent and event horizons except for the case of logarithmic entropic correction at apparent horizon. Also, we check the thermodynamical equilibrium condition for all cases of entropy and found its vitality in all cases of entropy.

scholarly journals Sign-changeable interacting agegraphic dark energy in Brans–Dicke cosmology

2020 ◽  
Vol 98 (7) ◽  
pp. 643-649
Author(s):  
M. Abdollahi Zadeh ◽  
A. Sheykhi
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
The State ◽  
Evolutionary Equation ◽  
Model Parameters ◽  
Late Time ◽  
Frw Universe ◽  
Agegraphic Dark Energy ◽  
Deceleration Phase ◽  
The Universe

We explore a spatially homogeneous and isotropic Friedmann–Robertson–Walker (FRW) universe that is filled with agegraphic dark energy (ADE) with mutual interaction with pressureless dark matter in the background of Brans–Dicke (BD) theory. We consider both original and a new type of ADE (NADE) and further assume that the sign of the interaction term can change during the history of the universe. We obtain the equation of the state parameter, the deceleration parameter, and the evolutionary equation for the sign-changeable interacting ADE and NADE in BD cosmology. We find that in both models, the equation of the state parameter, wD, cannot cross the phantom line, although they can predict the universe evolution from the early deceleration phase to the late time acceleration, compatible with observations. We also investigate the sound stability of these models and find out that both models cannot show a signal of stability for different model parameters.

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.

Generalized ghost pilgrim dark energy in f(G,T) gravity

2019 ◽  
Vol 28 (06) ◽  
pp. 1950077 ◽  
Author(s):  
M. Sharif ◽  
Saadia Saba
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Momentum Tensor ◽  
Chaplygin Gas ◽  
Frw Universe ◽  
Pilgrim Dark Energy ◽  
Energy Formula ◽  
Text Model ◽  
The Universe ◽  
Friedmann Robertson Walker

In this paper, we explore the reconstruction paradigm for generalized ghost pilgrim dark energy model with [Formula: see text] gravity ([Formula: see text] is the Gauss–Bonnet invariant and [Formula: see text] is the trace of the energy–momentum tensor) depending upon the speculation of black hole-free universe. To accomplish this, we adopt correspondence scheme for dust fluid configuration with flat Friedmann-Robertson-Walker (FRW) universe. The cosmic behavior of reconstructed models is examined through cosmological diagnostic parameters and phase planes. It is found that the deceleration parameter indicates accelerated phase while equation-of-state parameter represents phantom regime for some specific range of free parameters. The squared speed of sound parameter gives stable models for analyzing evolutionary paradigm of the universe. The trajectories of [Formula: see text]–[Formula: see text] plane gives thawing region, whereas [Formula: see text]–[Formula: see text] phase plane corresponds to Chaplygin gas model. We conclude that the resulting model represents self-consistent phantom-like universe for [Formula: see text] cannot be fraction) as well as stable generalized ghost pilgrim dark energy [Formula: see text] model.

scholarly journals Model Independent Diagnostics in Interacting Dark Energy Models

Universe ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 49
Author(s):  
Ying Jiang ◽  
Zhongxu Han ◽  
Qian Zhang ◽  
Weiqiang Yang ◽  
Yabo Wu ◽  
...  
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Cold Dark Matter ◽  
Coupling Parameter ◽  
Gravitational Interaction ◽  
Coupled Model ◽  
State Parameter ◽  
Energy Model ◽  
The State ◽  
Eos Parameter

In this paper, we have explored non-gravitational interaction dark energy model between dark energy and cold dark matter (CDM). The main purpose of this work is to explore the deviations from Λ C D M and to distinguish the evolution trajectory of the interaction dark energy model with different parameters. Six forms of interaction were focused on. We have analyzed the deceleration parameters of the coupled model and explored the theoretical models through s t a t e f i n d e r h i e r a r c h y and the O m diagnostic. We have considered that the Equation of State (EoS) parameter w and parameter ξ take different values on the interaction dark energy model respectively and keep another parameter unchanged. It was found that q ( z ) is the worst of the four diagnoses. O m , S 3 ( 1 ) and S 4 ( 1 ) are good tools to distinguish the interaction dark energy model from Λ C D M . S 3 ( 1 ) is a better diagnostic tool when the state parameter w changes and the coupling parameter ξ is fixed, while S 4 ( 1 ) works better when the coupling parameter ξ changes and the state parameter w is fixed.

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 Tsallis Holographic Dark Energy with Granda-Oliveros Scale in (n+1)-Dimensional FRW Universe

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Ayman A. Aly
Keyword(s):  
Dark Energy ◽  
Speed Of Sound ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Holographic Dark Energy Model ◽  
Frw Universe ◽  
Accelerating Expansion ◽  
The Stability ◽  
The Universe ◽  
Friedmann Robertson Walker

Based on Tsallis holographic dark energy model recently proposed by using the general model of the Tsallis entropy expression, we reconstruct cosmographic parameters, q,j,κ,l, and we study their evolution in spatially flat (n+1)-dimensional Friedmann-Robertson-Walker universe using Granda-Oliveros scale. Our results show that the universe is in an accelerating expansion mode described by phantom-like behavior. We go further and study the state finder operators and the Om diagnostic to understand the behavior of our model. The stability of the system is also studied by using the square of speed of sound showing that our model is stable over the low range of red-shift considered. The results indicate that the entropy formalism will play an important role in understanding the dynamics of our universe.

scholarly journals Cosmological Implications of the Generalized Entropy Based Holographic Dark Energy Models in Dynamical Chern-Simons Modified Gravity

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
M. Younas ◽  
Abdul Jawad ◽  
Saba Qummer ◽  
H. Moradpour ◽  
Shamaila Rani
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Modified Gravity ◽  
Dark Energy Model ◽  
State Parameter ◽  
Energy Model ◽  
Evolutionary Equation ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Chern Simons

Recently, Tsallis, Rényi, and Sharma-Mittal entropies have widely been used to study the gravitational and cosmological setups. We consider a flat FRW universe with linear interaction between dark energy and dark matter. We discuss the dark energy models using Tsallis, Rényi, and Sharma-Mittal entropies in the framework of Chern-Simons modified gravity. We explore various cosmological parameters (equation of state parameter, squared sound of speed ) and cosmological plane (ωd-ωd′, where ωd′ is the evolutionary equation of state parameter). It is observed that the equation of state parameter gives quintessence-like nature of the universe in most of the cases. Also, the squared speed of sound shows stability of Tsallis and Rényi dark energy model but unstable behavior for Sharma-Mittal dark energy model. The ωd-ωd′ plane represents the thawing region for all dark energy models.

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