scholarly journals Evolution of spherical overdensities in new agegraphic dark energy model

2017 ◽  
Vol 26 (09) ◽  
pp. 1750101
Author(s):  
M. R. Setare ◽  
F. Felegary ◽  
F. Darabi
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Frw Cosmology ◽  
Spherical Region ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Energy Models ◽  
Spherical Collapse ◽  
Collapse Model

We study the structure formation by investigating the spherical collapse model in the context of new agegraphic dark energy (NADE) model in flat FRW cosmology. We compute the perturbational quantities [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] for the NADE model and compare the results with those of EdS and [Formula: see text] models. We find that there is a dark energy-dominated universe at low redshifts and a matter-dominated universe at high redshifts in agreement with the observations. Also, the size of structures, the overdense spherical region, and the halo size in the NADE model are found to be smaller, denser, and larger than those of EdS and [Formula: see text] models. We compare our results with the results of tachyon scalar field and holographic dark energy models.

scholarly journals NEW AGEGRAPHIC DARK ENERGY MODEL WITH GENERALIZED UNCERTAINTY PRINCIPLE

2008 ◽  
Vol 23 (36) ◽  
pp. 3049-3055 ◽  
Author(s):  
YONG-WAN KIM ◽  
HYUNG WON LEE ◽  
YUN SOO MYUNG ◽  
MU-IN PARK
Keyword(s):  
Dark Energy ◽  
Early Universe ◽  
Uncertainty Principle ◽  
Dark Energy Model ◽  
Generalized Uncertainty Principle ◽  
Critical Value ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
The Past ◽  
Energy Models

We investigate the new agegraphic dark energy models with generalized uncertainty principle (GUP). It turns out that although the GUP affects the early universe, it does not change the current and future dark energy-dominated universe significantly. Furthermore, this model could describe the matter-dominated universe in the past only when the parameter n is chosen to be n > n c , where the critical value is determined to be n c = 2.799531478.

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 INTERACTING MODEL OF NEW AGEGRAPHIC DARK ENERGY: COSMOLOGICAL EVOLUTION AND STATEFINDER DIAGNOSTIC

2010 ◽  
Vol 19 (01) ◽  
pp. 21-35 ◽  
Author(s):  
LI ZHANG ◽  
JINGLEI CUI ◽  
JINGFEI ZHANG ◽  
XIN ZHANG
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Cosmological Evolution ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Evolution Of The Universe ◽  
Energy Models ◽  
The Universe ◽  
Matter Component

The statefinder diagnostic is a useful method for distinguishing different dark energy models. In this paper, we investigate the new agegraphic dark energy model with interaction between dark energy and matter component by using statefinder parameter pair {r, s} and study its cosmological evolution. We plot the trajectories of the new agegraphic dark energy model for different interaction cases in the statefinder plane. As a result, the influence of the interaction on the evolution of the universe is shown in the statefinder diagrams.

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 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 Tsallis agegraphic dark energy model

2019 ◽  
Vol 34 (11) ◽  
pp. 1950086 ◽  
Author(s):  
M. Abdollahi Zadeh ◽  
A. Sheykhi ◽  
H. Moradpour
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Dark Energy Model ◽  
Late Time ◽  
Conformal Time ◽  
Classical Level ◽  
Agegraphic Dark Energy ◽  
Energy Models ◽  
Age Of The Universe ◽  
The Universe

Using the non-extensive Tsallis entropy and the holographic hypothesis, we propose a new dark energy (DE) model with timescale as infrared (IR) cutoff. Considering the age of the Universe as well as the conformal time as IR cutoffs, we investigate the cosmological consequences of the proposed DE models and study the evolution of the Universe filled by a pressureless matter and the obtained DE candidates. We find that although this model can describe the late time acceleration and the density, deceleration and the equation of state parameters show satisfactory behavior by themselves, these models are classically unstable unless the interaction between the two dark sectors of the Universe is taken into account. In addition, the results of the existence of a mutual interaction between the cosmos sectors are also addressed. We find out that the interacting models are stable at the classical level which is in contrast to the original interacting agegraphic dark energy models which are classically unstable [K. Y. Kim, H. W. Lee and Y. S. Myung, Phys. Lett. B 660, 118 (2008)].

COSMOLOGICAL EVOLUTION OF NEW-AGEGRAPHIC DARK ENERGY MODEL

2008 ◽  
Vol 23 (17n20) ◽  
pp. 1366-1371 ◽  
Author(s):  
H. W. LEE ◽  
K. Y. KIM ◽  
Y. S. MYUNG
Keyword(s):  
Dark Energy ◽  
Differential Equations ◽  
Dark Energy Model ◽  
Critical Value ◽  
Energy Model ◽  
Cosmological Evolution ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy

We investigate the cosmological evolution of the new-agegraphic dark energy model which was recently proposed to explain the dark energy-dominated universe. For this purpose, we derived differential equations for density parameters and solved them numerically. We found that there exist a critical value for undetermined parameter of new-agegraphic density to obtain a stable and accessible evolution in the far past. Furthermore, this parameter seems to be fixed as the critical value for consistence.

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