Agegraphic Dark Energy Model Research Articles

Cosmological evolution of new Tsallis agegraphic dark energy with conformal time as IR-cutoff

This paper considers the only sectors to constitute the present universe as the dark matter and dark energy. The proposed new agegraphic dark energy model studies the gradual transition from matter to dark energy in sequential order, including the current dominance of the matter sector by dark energy. The model utilizes concepts of Tsallis entropy and the Karolyhazy relation with conformal time [Formula: see text] as the time scale. Various evolutionary aspects of the universe are characterized by Tsallis parameter [Formula: see text] and the model constant [Formula: see text]. Expressions for dynamic behavior of dark energy, as a differential equation, equation of state and deceleration parameters are obtained to describe the thermal history of universe evolution. Also, the stability of the model is analyzed through squared sound speed parameter. The analysis is made by considering an interaction as well as independence among the constituent sectors of the universe.

New agegraphic dark energy model with bulk viscosity

New agegraphic dark energy (NADE) model with bulk viscosity is proposed by assuming that the universe is composed of the NADE and dark matter, and both the dark components have a bulk viscosity. At the matter-dominated epoch, the density parameter and the equation of state (EoS) of the viscous NADE are given by [Formula: see text] and [Formula: see text], respectively, where [Formula: see text] and [Formula: see text] are viscosity parameters. In the late time [Formula: see text], the NADE dominates [Formula: see text] and [Formula: see text]. Owing to the special analytic features at the matter-dominated epoch for the viscous NADE model, the initial condition [Formula: see text] at [Formula: see text] is used to solve the differential equation of [Formula: see text], and the other physical quantities can be obtained correspondingly. We also find that the viscosity of dark matter affects the current density and the start time of the cosmic acceleration. However, in the late time [Formula: see text] only depends on the viscosity of the dark energy. Furthermore, we investigate the viscous NADE model by means of statefinder diagnostic. The viscosity of dark matter significantly affects the evolution of the statefinder parameters. Therefore, the bulk viscosity plays a significant role in the cosmological evolution.

The cosmological behavior and geometrical diagnostic for new Tsallis agegraphic dark energy with sign-changeable interaction

We explore the cosmic behavior of the sign-changeable interacting new Tsallis agegraphic dark energy (NTADE) model in a spatially flat universe. The deceleration and the equation of state (EoS) parameters of the model are calculated. We also investigate the model in the universe with the spatial curvature. The spatial curvature may affect the time of onset of the acceleration. Furthermore, we demonstrate two geometric diagnostics analyses including the statefinder [Formula: see text] and [Formula: see text] to the discriminant the model from the standard LCDM model. The trajectories of evolution for [Formula: see text] and [Formula: see text] diagnostic planes are shown for different Tsallis parameter [Formula: see text] and interaction parameter [Formula: see text].

Reconstructing extended f(P) cubic gravity from entropy-corrected holographic and new agegraphic dark energy models

This work deals with the newly approached extended [Formula: see text] cubic gravity in a cosmological background where [Formula: see text] denotes the cubic gravity. Here, we peruse the cosmological nature of the different types of dark energy candidates in the framework of [Formula: see text] gravity. Next, we study the reconstruction scenario of [Formula: see text] gravity model according to ordinary holographic dark energy, ordinary new agegraphic dark energy, entropy-corrected holographic dark energy in power-law and logarithmic versions and entropy-corrected new agegraphic dark energy in power-law and logarithmic versions with two classes of the scale factor. We derive different forms of the unknown function [Formula: see text] in the context of these dark energy candidates. By the trajectories of the EoS parameter [Formula: see text], all models give evidence of their candidature for the explanation of the phantom regime and also the quintessence regime in the late stage of the universe. Also, the stability condition ensures that our reconstructed models are classically stable.

New Tsallis agegraphic dark energy

The proposed model is a study of the nature of dark energy through nonextensive Tsallis entropy. The method is based on the Karolyhazy relation which is a combined idea from quantum physics and general relativity. Dark energy is the energy density of quantum fluctuations in spacetime. This is the key idea behind proposing agegraphic dark energy (ADE) models here. The parameter [Formula: see text] is used to measure the quantitative distinction from the standard scenario. To look at the cosmological implications of the hypothesized dark energy model, as well as the expansion of the universe filled with zero pressure matter and the resulting dark energy alternatives, the role of IR cutoff is played by age of the universe. The dynamic behavior of dark energy density parameter is carried out. The expressions for the equation of state parameter and deceleration parameter are obtained. The analysis is performed by taking into account a no flow as well as a flow of energy among the dark matter and dark energy sectors of the universe.

Agegraphic model based on the generalized uncertainty principle

Many models of dark energy have been proposed to describe the universe since the beginning of the Big Bang. In this study, we present a new model of agegraphic dark energy based on the three generalized uncertainty principles KMM (Kempf, Mangan, Mann), Nouicer and [Formula: see text] (higher orders generalized uncertainty principle). Using the obtained relations from three types of Generalized Uncertainty Principle (GU P), in the form of three scenarios (Emergent, Intermediate, Logamediate), we consider three different eras of the universe evolution. Also, we describe the evolution and expansion of the universe in each subsection. We will plot the obtained relations in these models for better comparatione.

Anisotropic new agegraphic dark energy model with sign-changeable interaction in a scalar-tensor theory

Anisotropic new agegraphic dark energy model with sign-changeable interaction in a scalar-tensor theory

Agegraphic dark energy cosmology and Quantum loop-correction

In this paper, we extend the agegraphic dark energy model through quantum loop-correction on Einstein–Hilbert action. We investigate the evolution of the equation of state and energy density of proposed agegraphic dark energy for non-interaction and interaction scenarios. Also, the deceleration parameter and square of sound speed of both scenarios are studied and we have shown model is stable classically only for the interaction case. Moreover, considering the interaction scenario shows for the very early universe, this new agegraphic dark energy may treat such as inflation field.

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

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.

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

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.

Exploring the new Tsallis agegraphic dark energy with interaction through statefinder

In this work, we explore the recently proposed new Tsallis agegraphic dark energy model in a flat FLRW Universe by taking the conformal time as IR cutoff with interaction. The deceleration parameter of the interacting new Tsallis agegraphic dark energy model provides the phase transition of the Universe from decelerated to accelerated phase. The EoS parameter of the model shows a rich behaviour as it can be quintessence-like or phantom-like depending on the interaction ($b^2$) and parameter $B$. The evolutionary trajectories of the statefinder parameters and $(\omega_D, \omega_D^{'})$ planes are plotted by considering the initial condition $\Omega_{D}^{0} =0.73$, $H_{0}= 67$ according to $\Lambda$CDM observational Planck 2018 data for different $b^2$ and $B$. The model shows both quintessence and Chaplygin gas behaviour in the statefinder $(r, s)$ and $(r, q)$ pair planes for different $b^2$ and $B$.

The cosmological behavior and the statefinder diagnosis for the New Tsallis agegraphic dark energy

In this work, we have considered the recently proposed new Tsallis agegraphic dark energy (NTADE) model [Mod. Phys. Lett. A 34, 1950086 (2019)] within the framework of a flat Friedmann–Robertson–Walker (FRW) Universe by taking various values of the parameter [Formula: see text]. The NTADE model shows the current phase transition of the Universe from decelerated to accelerated phase. The NTADE equation of state (EoS) parameter shows a rich behavior as it can be quintessence-like or phantom-like depending on the value of [Formula: see text]. For discriminating the NTADE model from [Formula: see text]CDM, we have plotted the statefinder parameters [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text] pair. The NTADE model shows distinct evolutionary trajectories of their evolution in ([Formula: see text]) and ([Formula: see text]) plane. An analysis using the snap parameter and the [Formula: see text] pair dynamical analysis have also been performed.

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

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.

Reconstructing f(T) modified gravity from ECHDE and ECNADE models

We investigate alternative candidates to dark energy (DE) that can explain the current state of the Universe in the framework of the generalized teleparallel theory of gravity f(T), where T denotes the torsion scalar. To achieve this, we carry out a series of reconstructions taking into account the ordinary and entropy-corrected versions of the holographic and new agegraphic DE models. These models are used as alternatives to DE in the literature in order to describe the current state of our Universe. It is remarked that the proposed models indicate behavior akin to phantom or quintessence models. Furthermore, we also generate the parameters of the equation of state associated with entropy-corrected models and we observe a phase transition between the quintessence state and phantom state as it is shown by the recent observational data. We also investigate the stability of these models and we create the trajectories and compare with the ΛCDM limit. The behavior of certain physical parameters such as the speed of sound and the Statefinder diagnostic pair is compatible with the current observational data.

Thermodynamics of the viscous f(T,B) gravity in the new agegraphic dark energy model

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.

Tsallis agegraphic dark energy model with the sign-changeable interaction

In this paper, we study the evolution of a spatially flat universe composed of Tsallis agegraphic dark energy (TADE) and a pressureless dark matter (DM), by assuming that there is a sign-changeable interaction between TADE and DM. The density, deceleration parameter and the equation of state parameters (EoS) show satisfactory behaviors in the model. By analysis we find that the accelerated expansion of the universe can be achieved at the late time if model parameters δ > 2 and −2/3 < β < 0. Also, we investigate the interacting TADE model by means of statefinder diagnostic and analysis.

Tsallis, Rényi and Sharma-Mittal holographic and new agegraphic dark energy models in D-dimensional fractal universe

In this work, we explore the accelerated expansion of the Universe through a non-linear interaction of newly proposed dark energy models (namely Tsallis holographic dark energy (HDE), Renyi HDE, Sharma Mittal HDE, Tsallis new agegraphic dark energy (NADE), Renyi NADE and Sharma-Mittal NADE) with cold dark matter in the background of flat D -dimensional fractal Universe. The effect of IR cutoffs including the Hubble radius and Granda-Oliveros (GO) on the properties of the considered dark energy models have been investigated in this context. The cosmological parameters such as equation of state (EoS) parameter, squared speed of sound and $ \omega_{d}$ - $ \omega^{\prime}_{d}$ cosmological plane during the cosmic evolution have been calculated. Analyzing the behavior of such cosmological parameters graphically, it is found that the considered HDE and NADE models can lead to the late time accelerated expansion in the presence of interaction between two dark sectors of the Universe in more general space-time. This result is similar to the standard interacting HDE model with Hubble cutoff in FRW Universe.

Interacting agegraphic dark energy model in DGP brane-world cosmology: Dynamical system approach

A proposal to study the effect of interaction in an agegraphic dark energy model in DGP brane-world cosmology is presented in this paper. After explaining the details, we proceed to apply the dynamical system approach to the model to analyze its stability. We first constrain model parameters with a variety of independent observational data such as cosmic microwave background anisotropies, baryon acoustic oscillation peaks and observational Hubble data. Then, we obtain the critical points related to different cosmological epochs. In particular, we conclude that in the presence of interaction, dark energy dominated era could be a stable point if model parameters n and [Formula: see text], obey a given constraint. Also, big rip singularity is avoidable in this model.

New agegraphic dark energy in f(G, T) gravity

This paper is devoted to the reconstruction paradigm for new agegraphic dark energy model in the context of f(G, T) gravity (G and T denote the Gauss–Bonnet invariant and trace of the energy-momentum tensor). To accomplish this, we choose the correspondence scenario for pressureless perfect fluid configuration in the framework of flat FRW universe. The cosmic behavior of reconstructed models is analyzed through cosmic diagnostic parameters and phase planes. It is found that the deceleration parameter indicates accelerated regime while the equation of state parameter gives the phantom phase for non-conserved and quintessence universe for conserved energy-momentum tensor. The squared speed of sound parameter represents the stability of the conserved model for late-time cosmic evolutionary paradigm whereas instability for the non-conserved regime. The trajectories of ωeff−ωeff′ plane correspond to thawing as well as freezing region for the non-conserved and conserved scenario, respectively. The r−s plane gives phantom as well as the non-phantom regime for conserved and Chaplygin gas model for the non-conserved paradigm. We conclude that the resulting models exhibit self-consistent quintessence as well as the phantom-like universe for appropriate choice of free parameters.

Tsallis agegraphic dark energy model

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)].