Analysis of entropy corrected holographic and new agegraphic dark energy models in generalized Rastall gravity

2020 ◽  
Vol 35 (28) ◽  
pp. 2050175
Author(s):  
Sayani Maity ◽  
Mahasweta Biswas ◽  
Ujjal Debnath
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Graphical Analysis ◽  
Future Singularity ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Energy Models ◽  
Dark Energy Component ◽  
The Stability

This work deals with two fluid system in the framework of generalized Rastall gravity theory. One component represents dark energy whereas the other is dark matter. For the dark energy component, entropy corrected holographic and entropy corrected new agegraphic dark energy models in power-law and logarithmic versions are taken into account. For this study, we assume two classes of scale factors in which one corresponds to the future singularity and another corresponds to the initial singularity. For each of the entropy corrected dark energy models, the cosmological parameters such as Hubble parameter, deceleration parameter and equation of state parameter are calculated and their implications are established. Furthermore, to describe the stability analysis of the models, the behaviors of the squared speed of sound are analyzed graphically for each of these models. From the graphical analysis of [Formula: see text] plane, the thawing or freezing regions of all the models are determined.

scholarly journals Cosmological aspects of sound speed parameterizations in fractal universe

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Abdul Jawad ◽  
Sadaf Butt ◽  
Shamaila Rani ◽  
Khadija Asif
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Speed Of Sound ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Graphical Analysis ◽  
Eos Parameter ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
The Universe

AbstractIn the framework of fractal universe, the unified models of dark energy and dark matter are being presented with the background of homogenous and isotropic FLRW geometry. The aspects of fractal cosmology helps in better understanding of the universe in different dimensions. Relationship between the squared speed of the sound and the equation of state parameter is the key feature of these models. We have used constant as well as variable forms of speed of sound and express it as a function of equation of state parameter. By utilizing the four different forms of speed of sound, we construct the energy densities and pressures for these models and then various cosmological parameters like hubble parameter, EoS parameter, deceleration parameter and Om- diagnostic are investigated. Graphical analysis of these parameters show that in most of the cases EoS parameters and trajectories of Om-diagnostic corresponds to the quintessence like nature of the universe and the deceleration parameters represent accelerated and decelerated phase. In the end, we remark that cosmological analysis of these models indicates that these models correspond to different well known dark energy models.

Cosmological consequences of Rényi, Sharma–Mittal holographic and new agegraphic dark energy models in generalized Rastall gravity

2021 ◽  
pp. 2150180
Author(s):  
Alok Sardar ◽  
Ujjal Debnath
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Future Event ◽  
Fluid System ◽  
Future Singularity ◽  
Eos Parameter ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Energy Models ◽  
Two Fluid

The main motivation of our study is to explore Rényi holographic dark energy, Sharma–Mittal holographic dark energy, Rényi new agegraphic dark energy, and Sharma–Mittal new agegraphic dark energy in the context of generalized Rastall gravity with the two-fluid system, dark energy, and dark matter. In this regard, we have considered the scale factors into two distinct categories, one of which corresponds to the future singularity, whereas the other represents initial singularity. By employing future event horizon as infrared (IR)-cutoff, different cosmological quantities like deceleration parameter, equation of state (EoS) parameter are evaluated, and their ramifications have been described graphically. Analyzing the squared speed of sound, we have seen classically stable and unstable behavior for each of the considered models. Finally, we study [Formula: see text]–[Formula: see text] plane and find the thawing/freezing regions.

scholarly journals Cosmic Consequences of Kaniadakis and Generalized Tsallis Holographic Dark Energy Models in the Fractal Universe

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Abdul Jawad ◽  
Abdul Malik Sultan
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Apparent Horizon ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Accelerated Expansion ◽  
Energy Models ◽  
Expansion Of The Universe ◽  
The Stability ◽  
The Universe

We investigate the recently proposed holographic dark energy models with the apparent horizon as the IR cutoff by assuming Kaniadakis and generalized Tsallis entropies in the fractal universe. The implications of these models are discussed for both the interacting ( Γ = 3 H b 2 ρ m ) and noninteracting ( b 2 = 0 ) cases through different cosmological parameters. Accelerated expansion of the universe is justified for both models through deceleration parameter q . In this way, the equation of state parameter ω d describes the phantom and quintessence phases of the universe. However, the coincidence parameter r ~ = Ω m / Ω d shows the dark energy- and dark matter-dominated eras for different values of parameters. It is also mentioned here that the squared speed of sound gives the stability of the model except for the interacting case of the generalized Tsallis holographic dark energy model. It is mentioned here that the current dark energy models at the apparent horizon give consistent results with recent observations.

scholarly journals FORMATION OF DARK MATTER HALOES IN A HOMOGENEOUS DARK ENERGY UNIVERSE

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1397-1403
Author(s):  
L. MARASSI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Large Scale ◽  
State Parameter ◽  
Mass Function ◽  
Accelerated Expansion ◽  
X Ray ◽  
Energy Models ◽  
Dark Energy Component ◽  
Standard Press

Several independent cosmological tests have shown evidences that the energy density of the universe is dominated by a dark energy component, which causes the present accelerated expansion. The large scale structure formation can be used to probe dark energy models, and the mass function of dark matter haloes is one of the best statistical tools to perform this study. We present here a statistical analysis of mass functions of galaxies under a homogeneous dark energy model, proposed in the work of Percival (2005), using an observational flux-limited X-ray cluster survey, and CMB data from WMAP. We compare, in our analysis, the standard Press–Schechter (PS) approach (where a Gaussian distribution is used to describe the primordial density fluctuation field of the mass function), and the PL (power–law) mass function (where we apply a non-extensive q-statistical distribution to the primordial density field). We conclude that the PS mass function cannot explain at the same time the X-ray and the CMB data (even at 99% confidence level), and the PS best fit dark energy equation of state parameter is ω = -0.58, which is distant from the cosmological constant case. The PL mass function provides better fits to the HIFLUGCS X-ray galaxy data and the CMB data; we also note that the ω parameter is very sensible to modifications in the PL free parameter, q, suggesting that the PL mass function could be a powerful tool to constrain dark energy models.

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 Dynamics of nonlinear interacting dark energy models

2019 ◽  
Vol 28 (12) ◽  
pp. 1950161 ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Supriya Pan ◽  
Weiqiang Yang
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Critical Points ◽  
Cosmological Parameters ◽  
Late Time ◽  
Interacting Dark Energy ◽  
Energy Models ◽  
Flrw Universe ◽  
The Stability ◽  
Interacting Dark Energy Models

We investigate the cosmological dynamics of interacting dark energy models in which the interaction function is nonlinear in terms of the energy densities. Considering explicitly the interaction between a pressureless dark matter and a scalar field, minimally coupled to Einstein gravity, we explore the dynamics of the spatially flat FLRW universe for the exponential potential of the scalar field. We perform the stability analysis for three nonlinear interaction models of our consideration through the analysis of critical points and we investigate the cosmological parameters and discuss the physical behavior at the critical points. From the analysis of the critical points we find a number of possibilities that include the stable late-time accelerated solution, [Formula: see text]CDM-like solution, radiation-like solution and moreover the unstable inflationary solution.

scholarly journals Correspondence off(R,∇R)Modified Gravity with Scalar Field Models

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Abdul Jawad ◽  
Ujjal Debnath
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
State Parameter ◽  
Scalar Fields ◽  
Frw Universe ◽  
Tachyonic Field ◽  
Energy Models ◽  
The Stability ◽  
Scalar Potentials ◽  
The Universe

This paper is devoted to study the scalar field dark energy models by taking its different aspects in the framework off(R,∇R)gravity. We consider flat FRW universe to construct the equation of state parameter governed byf(R,∇R)gravity. The stability of the model is discussed with the help of squared speed of sound parameter. It is found that models show quintessence behavior of the universe in stable as well as unstable modes. We also develop the correspondence off(R,∇R)model with some scalar field dark energy models like quintessence, tachyonic field,k-essence, dilaton, hessence, and DBI-essence. The nature of scalar fields and corresponding scalar potentials is being analyzed inf(R,∇R)gravity graphically which show consistency with the present day observations about accelerated phenomenon.

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