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.

Viability of specific reconstructed f(T,𝒯 ) models

2019 ◽  
Vol 34 (30) ◽  
pp. 1950184
Author(s):  
M. Umair Shahzad ◽  
Nadeem Azhar ◽  
Abdul Jawad ◽  
Shamaila Rani
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Dark Energy Model ◽  
State Parameter ◽  
Pilgrim Dark Energy ◽  
Ghost Dark Energy ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Hubble Horizon ◽  
The Universe

The reconstruction scenario of well-established dark energy models such as pilgrim dark energy model and generalized ghost dark energy with Hubble horizon and [Formula: see text] models is being considered. We have established [Formula: see text] models and analyzed their viability through equation of state parameter and [Formula: see text] (where prime denotes derivative with respect to [Formula: see text]) plane. The equation of state parameter evolutes the universe in three different phases such as quintessence, vacuum and phantom. However, the [Formula: see text] plane also describes the thawing as well as freezing region of the universe. The recent observational data also favor our results.

Generalized ghost Tsallis holographic dark energy model in RS-II braneworld and dynamical Chern-Simons modified gravity

2020 ◽  
Vol 17 (08) ◽  
pp. 2050124
Author(s):  
Abdul Jawad ◽  
Sabir Hussain ◽  
Shamaila Rani ◽  
Saba Qummer
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Modified Gravity ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Frw Universe ◽  
Om Diagnostic ◽  
Equation Of State Parameter ◽  
Chern Simons

In this paper, we studied the cosmological implications of generalized ghost Tsallis holographic dark energy in the framework of Randall–Sundrum II braneworld and Chern–Simons modified gravity in flat FRW universe. We discuss the cosmological parameters like equation of state parameter, deceleration parameter, squared speed of sound, Om-diagnostic and planes like evolving equation of state parameter and statefinders. These models yield useful results in this context.

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 Cosmological Consequences of New Dark Energy Models in Einstein-Aether Gravity

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 509 ◽  
Author(s):  
Shamaila Rani ◽  
Abdul Jawad ◽  
Kazuharu Bamba ◽  
Irfan Malik
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Graphical Representation ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Effective Density ◽  
Evolutionary Equation ◽  
Model Parameters ◽  
Energy Models ◽  
Equation Of State Parameter

In this paper, we reconstruct various solutions for the accelerated universe in the Einstein-Aether theory of gravity. For this purpose, we obtain the effective density and pressure for Einstein-Aether theory. We reconstruct the Einstein-Aether models by comparing its energy density with various newly proposed holographic dark energy models such as Tsallis, Rényi and Sharma-Mittal. For this reconstruction, we use two forms of the scale factor, power-law and exponential forms. The cosmological analysis of the underlying scenario has been done by exploring different cosmological parameters. This includes equation of state parameter, squared speed of sound and evolutionary equation of state parameter via graphical representation. We obtain some favorable results for some values of model parameters

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.

scholarly journals Cosmological Analysis of Modified Holographic Ricci Dark Energy in Chern-Simons Modified Gravity

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Sarfraz Ali ◽  
M. Jamil Amir
Keyword(s):  
Dark Energy ◽  
Modified Gravity ◽  
Dark Energy Model ◽  
State Parameter ◽  
Scalar Fields ◽  
Energy Model ◽  
Accelerated Expansion ◽  
Ricci Dark Energy ◽  
Dominant Component ◽  
Chern Simons

In this paper, we study the cosmological analysis of the modified holographic Ricci dark energy model and reconstruct different scalar field models in the context of Chern-Simons modified gravity. We investigate the deceleration parameter, which shows that the universe is in the accelerating expansion phase. The equation of state parameter in this case also favors the fact that dark energy is the dominant component of universe, which is responsible for the accelerated expansion. A number of scalar fields, such as quintessence, tachyon, K-essence, and dilaton models, are reconstructed using modified holographic Ricci dark energy model in the context of dynamical CS modified gravity. The quintessence and K-essence models represent exponentially increasing behaviors, while tachyon model shows decreasing behavior. Unfortunately, the dilaton model has no numerical solution for modified holographic Ricci dark energy model in the framework of dynamical Chern-Simons modified gravity.

scholarly journals Exploration of interacting dynamical dark energy model with interaction term including the equation-of-state parameter: alleviation of the H0 tension

2021 ◽  
Vol 2021 (12) ◽  
pp. 036
Author(s):  
Rui-Yun Guo ◽  
Lu Feng ◽  
Tian-Ying Yao ◽  
Xing-Yu Chen
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Dark Energy Model ◽  
State Parameter ◽  
Acoustic Oscillation ◽  
Energy Model ◽  
Equation Of State Parameter ◽  
Type Ia ◽  
Interaction Term ◽  
Dynamical Dark Energy

Abstract We explore a scenario of interacting dynamical dark energy model with the interaction term Q including the varying equation-of-state parameter w. Using the data combination of the cosmic microwave background, the baryon acoustic oscillation, and the type Ia supernovae, to global fit the interacting dynamical dark energy model, we find that adding a factor of the varying w in the function of Q can change correlations between the coupling constant β and other parameters, and then has a huge impact on the fitting result of β. In this model, the fitting value of H 0 is lower at the 3.54σ level than the direct measurement value of H 0. Comparing to the case of interacting dynamical dark energy model with Q excluding w, the model with Q including the constant w is more favored by the current mainstream observation. To obtain higher fitting values of H 0 and narrow the discrepancy of H 0 between different observations, additional parameters including the effective number of relativistic species, the total neutrino mass, and massive sterile neutrinos are considered in the interacting dynamical dark energy cosmology. We find that the H 0 tension can be further reduced in these models, but is still at the about 3σ level.

scholarly journals Analysis off(R)Theory Corresponding to NADE and NHDE

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
M. Sharif ◽  
M. Zubair
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Deceleration Parameter ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Future Evolution ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Effective Description

We develop the connection off(R)theory with new agegraphic and holographic dark energy models. The functionf(R)is reconstructed regarding thef(R)theory as an effective description for these dark energy models. We show the future evolution offand conclude that these functions represent distinct pictures of cosmological eras. The cosmological parameters such as equation of state parameter, deceleration parameter, statefinder diagnostic, andw−w′analysis are investigated which assure the evolutionary paradigm off.

scholarly journals STATEFINDER DIAGNOSTIC FOR THE YANG–MILLS DARK ENERGY MODEL

2008 ◽  
Vol 17 (08) ◽  
pp. 1245-1254 ◽  
Author(s):  
WEN ZHAO
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Dark Energy Model ◽  
Energy Model ◽  
Statefinder Parameters ◽  
Yang Mills ◽  
Energy Models

We study the statefinder parameters in the Yang–Mills condensate dark energy models, and find that the evolving trajectories of these models are different from those of other dark energy models. We also define two eigenfunctions of the Yang–Mills condensate dark energy models. The values of these eigenfunctions are quite close to zero if the equation of state of the Yang–Mills condensate is not far from -1, which can be used to simply differentiate between the Yang–Mills condensate models and other dark energy models.

A study on the modified holographic Ricci dark energy in logarithmic f(T) gravity

2013 ◽  
Vol 91 (4) ◽  
pp. 351-354 ◽  
Author(s):  
Antonio Pasqua ◽  
Surajit Chattopadhyay
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
State Parameter ◽  
Ricci Dark Energy ◽  
Equation Of State Parameter ◽  
Interaction Term ◽  
The Universe

In this paper, we have studied and investigated the behavior of a modified holographic Ricci dark energy (DE) model interacting with pressureless dark matter (DM) under the theory of modified gravity, dubbed logarithmic f(T) gravity. We have chosen the interaction term between DE and DM in the form Q = 3γHρm and investigated the behavior of the torsion, T, the Hubble parameter, H, the equation of state parameter, ωDE, the energy density of DE, ρDE, and the energy density contribution due to torsion, ρT, as functions of the redshift, z. We have found that T increases with the redshift, z, H increases with the evolution of the universe, ωDE has a quintessence-like behavior, and both energy densities increase going from higher to lower redshifts.

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