Generalized Ghost Dark Energy Research Articles

Analysis of cosmic evolution admitting Garcia-Salcedo ghost and generalized ghost dark energy models

This study aims to explore the Garcia-Salcedo ghost dark energy and generalized ghost dark energy models in the context of f(R,T2) theory, where R is the Ricci scalar and T2 is the self-contraction of stress–energy tensor. We investigate the non-interacting case only corresponding to flat Friedmann–Robertson–Walker universe. We reconstruct the corresponding f(R,T2) gravity models using the considered dark energy models by taking two particular models of this gravity. The stability analysis is performed for all the cases. The behavior of the equation of state parameter is also checked. It is found that some of the reconstructed f(R,T2) models successfully describe both the phantom and quintessence epochs of the universe, which support the current cosmic accelerated expansion. This exploration reveals the intricate connections between dark energy models and modified gravitational theory, providing significant understanding into the dynamics of the cosmos on a large scale.

Generalized ghost dark energy model in Brans–Dicke theory with logarithmic scalar field

We study generalized ghost dark energy model in Brans–Dicke theory within the framework of flat Friedmann–Lemaitre–Robertson–Walker Universe. We assume the well-motivated logarithmic form of Brans–Dicke scalar field in terms of the scale factor to find the observational parameters such as equation of state parameter [Formula: see text] and deceleration parameter q. It is observed that the equation of state parameter crosses the phantom divide line [Formula: see text] for a suitable range of model parameters. We observe that the deceleration parameter is time-dependent which shows the recent phase transition from decelerated to accelerated expansion of the Universe. Moreover, the model shows that the Universe will go through two future phase transitions, recent accelerated expansion to decelerated expansion and again decelerated expansion to accelerated expansion. We have also plotted the trajectories of the model in the [Formula: see text] plane for different values of parameters and explored the freezing and thawing regions. Further, we apply the sound squared speed method to check the stability of the model and found that the model is stable for suitable range of parameters.

Generalized ghost dark energy in [formula omitted] gravity

In this manuscript, we use the correspondence principle to construct the generalized ghost dark energy f(Q) model, where Q is the non-metricity. For this purpose, we use the Friedman–Robertson–Walker universe model with power-law scale factor. The energy density in this model linearly depends on the Hubble parameter, with a sub-leading term of H2, resulting in an energy density ρD=ξH+ζH2, where ξ and ζ are arbitrary constants. We reconstruct interacting fluid scenario of this dark energy with dark matter. The reformulated f(Q) gravity model shows how different epochs of the cosmic history can be reproduced by this modified gravity model. The physical characteristics of the model are discussed through the equation of state parameter with the planes of ωD−ωD′ and r−s. We also explore the stability criteria for the interacting model using the squared speed of sound. The equation of state parameter indicates phantom phase of the universe and the squared speed of sound represents stability of the interacting model. The (ωD−ωD′)-plane indicates freezing region, while the (r−s)-plane corresponds to the Chaplygin gas. We conclude that our findings coincide with the latest observational data.

Analysis of generalized ghost dark energy and new holographic dark energy in Chameleon Brans–Dicke theory

In this work, we discuss the stability analysis of generalized ghost dark energy (GGDE) and new holographic dark energy (NHDE) in the framework of Chameleon Brans–Dicke (CBD) gravity. The adiabatic squared sound speed [Formula: see text] plays a crucial role to analyze the stability of the models. We know that the models are stable if [Formula: see text] and unstable if [Formula: see text]. We study the interacting and noninteracting versions of GGDE and NHDE with dark matter in CBD model in a nonflat FLRW universe. We also try to show that in all cases of investigation, the models are classically stable with suitable choices of parameters. Finally, we analyze the perturbative analysis for both GGDE and NHDE models in the background of CBD gravity.

Cosmological analysis of noninteracting and interacting generalized ghost dark energy in Einstein–Aether gravity theory

We have investigated the generalized QCD ghost model of dark energy (DE) in the framework of Einstein–Aether gravity. At first we have discussed the noninteracting generalized ghost DE (GGDE) model in flat Friedmann–Robertson–Walker (FRW) universe and then we have generalized the discussion to the interacting GGDE model in flat and nonflat universe. According to this, we have analyzed the nature of the equation of state (EoS) parameter, deceleration parameter and slow-roll parameters. We have used the sign of square speed of sound to determine the stability of the model in different cases. Also, we have analyzed [Formula: see text] plane in graphically and pointed out freezing region and thawing region in that plane. Then we enlarge our discussion to verify the effectiveness of this model under investigation by analyzing the statefinder diagnosis parameters for the present cosmological setup. The nature of slow-roll parameters in both scenarios with and without interactions has been shown diagrammatically.

Cosmic age problem in holographic and ghost dark energy models

ABSTRACT In this paper, we study the cosmic age problem in holographic (HDE) and generalized ghost dark energy (GGDE) models. To this end, we consider these two models in presence of non-linear interaction terms for three special cases, presented in the literature. We explain the impacts of the mentioned interaction terms on the cosmic age during the evolution of the Universe. There are many old cosmic objects (OCOs) which their evaluated age is not consistent with that of dark energy models. Here, we confine our attention on five cases of more known OCOs at different redshift. The purpose is to constrain the DE models, using the age of these OCOs. We obtain boundary values for free parameters of the HDE (b2 and c) using the age test and find that, such non-linear interactions can alleviate the age problem in spite of the linear one. The GGDE was already constrained using a joint analysis of data sets SHBC. We find a new bound for ξ that wasn’t predicted via SHBC analysis. Beside, we find that the GGDE can completely alleviate the cosmic age problem.

Ghost scalar field dark energy models from an extended Kaluza–Klein perspective

Reconstruction process of scalar field models (quintessence, tachyon, dilaton and K-essence), which can be performed by making use of some dark energy density definitions such as holographic, Ricci, new agegraphic and ghost types proposals, has been an interesting and very attractive area to many physicists in literature. In this work, in a five-dimensional framework, we establish a correspondence between the quintessence, tachyon and the dilaton type scalar field definitions and the generalized ghost dark energy model by considering the extended form of the Kaluza–Klein (EKK) gravity. Accordingly, we numerically study the associated equation of state parameters, as well as their kinetic energy and scalar potential terms.

Cosmic evolution of ghost dark energy models in f(G,T) gravity

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.

Generalized ghost dark energy in DGP model

In 2000, Dvali et al. [4-D gravity on a brane in 5-D Minkowski space, Phys. Lett. B 485 (2000) 208–214] proposed a new braneworld model named as DGP model, having two branches with [Formula: see text]. Former one [Formula: see text] known as accelerating branch, which explains accelerating phase of the Universe without adding cosmological constant or Dark energy (DE), whereas later one [Formula: see text] represents the decelerating branch. Here, we have investigated the behavior of Generalized Ghost Dark Energy (GGDE) under the decelerating branch of DGP model. We have studied the importance of GGDE model to explain the current phase of the Universe. To check the validity of the present model, we study the behavior of different cosmological parameters such as Hubble parameter, equation of state (EoS) parameter and deceleration parameter with respect to scale factor. Then, we have analyzed the [Formula: see text] to confirm no freezing region of this study and point out thawing region. Furthermore, we have checked the gradient of stability by calculating the squared sound speed. Then, we extend our study to check the viability of this model under investigation through the analysis of statefinder diagnosis parameters for the present cosmological setup.

Viability of specific reconstructed f(T,𝒯 ) models

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.

Bianchi type-III, V and VI0 generalized ghost dark energy models with polytropic gas in Brans-Dicke theory of gravitation

This paper elaborates the homogeneous and anisotropic Bianchi type-III, V and VI0 space times filled with matter and generalized ghost dark energy components in the framework of Brans-Dicke (Phys. Rev. 124, 925 1961) theory of gravitation. The behavior of generalized ghost dark energy for Bianchi type-III, V and VI0 background is discussed. The solutions of the field equations obtained using following two assumptions: (i) shear scalar of the model is proportional expansion scalar, which leads to a relation between the metric, (ii) scalar field in the Brans-Dicke theory is a function of average scale factor of the models. We have further established a correspondence between the generalized ghost dark energy models with the polytropic gas dark energy model. We also reconstructed the potential and dynamics of the scalar field. We discuss some physical and geometrical properties of the obtained models which are found to be consistent with recent observation.

Katowski-Sachs generalized ghost dark energy cosmological model in Saez-Ballester scalar -tensor theory

In this paper we have studied the Kantowski-Sachs (KS) space time filled with generalized ghost dark energy (GGDE) and dark matter in the Saez-Ballester theory of gravitation. The equation of state (EoS) parameter of dark energy (ωλ) has been formulated as a function of cosmic time and shows quintom like behavior. The properties of density of dark energy (ρλ) and the density of dark matter (ρm) indicate the accelerated expansion of the universe. The pressure of the dark energy is negative at present and late time evolution of the universe indicating the accelerated expansion of our universe during these periods. The physical and geometrical aspects of the statefinder parameters (r, s), squared speed of sound and plane are also discussed.

Study of QCD generalized ghost dark energy in FRW universe

A phenomenological generalized ghost dark energy model has been studied under the framework of FRW universe. In ghost dark energy model the energy density depends linearly on Hubble parameter (H) but in this dark energy model, the energy density contains a the sub-leading term which is depends on mathcal {O} (H^2), so the energy density takes the form rho _D=alpha H+ beta H^2, where alpha and beta are the constants. The solutions of the Friedman equation of our model leads to a stable universe. We have fitted our model with the present observational data including Stern data set. With the help of best fit results we find the adiabatic sound speed remains positive throughout the cosmic evolution, that claims the stability of the model. The flipping of the signature of deceleration parameter at the value of scale factor a=0.5 indicates that the universe is at the stage of acceleration i.e. de Sitter phase of the universe at late time. Our model shows that the acceleration of the universe begin at redshift z_{ace}approx 0.617 and the model is also consistent with the current observational data.

Ghost dark energy in the deformed Hořava–Lifshitz cosmology

We study the cosmological consequences of the ghost models of dark energy (DE) in the framework of Hořava–Lifshitz gravity. We calculate the equation-of-state parameter, the deceleration parameter, the classical stability and the dimensionless density parameter of the models in both noninteracting and interacting scenarios. We find that, for some values of the parameter, this model can admit a transition from the deceleration phase to the accelerated phase around [Formula: see text], while at the late time ([Formula: see text]) we have [Formula: see text] meaning that this model mimics a cosmological constant. We find that in the setup of Hořava–Lifshitz gravity, ghost dark energy (GDE) models are classically unstable. We observe that unlike the generalized ghost dark energy (GGDE), the ghost dark energy cannot provide proper behavior for all the cosmological parameters simultaneously, with the same values of the models’ couplings.

Cosmography of Generalized Ghost Dark Energy Model in f(G) Gravity

This paper is devoted to construction of generalized ghost dark energy f(G) model by using correspondence scheme for both interacting and noninteracting scenarios with pressureless matter and power-law scale factor. We study the cosmological implications of the resulting model through equation of state parameter and ωDE – $$\omega _{{DE}}^{'}$$ as well as r – s plane. We also discuss stability of the resulting model through squared speed of sound parameter. The equation of state parameter represents phantom phase of the Universe for both cases while the squared speed of sound indicates stability of this model. The ωDE – $$\omega _{{DE}}^{'}$$ plane represents thawing region whereas r – s plane corresponds to phantom and quintessence DE regimes for both interacting and noninteracting cases.

Anisotropic behavior of dark energy models in fractal cosmology

We study effects of anisotropy (although low) on the ghost and generalized ghost dark energy (DE) models in the framework of fractal cosmology. We obtain the equation of state parameter, [Formula: see text], the deceleration parameter, and the evolution equation of the ghost and generalized ghost dark energy. We find that, in both models, [Formula: see text] cannot cross the phantom line and eventually the universe approaches a de-Sitter phase of expansion. We show that the anisotropy effects on ghost and generalized ghost dark energy (GDE) in fractal cosmology correspond to [Formula: see text]CDM limit on the statefinder plane. We evaluate the anisotropy effects on both the linear perturbation and the spherical collapse from the DE models and compare them with the results of the DE of the Friedmann–Robertson–Walker and [Formula: see text]CDM models. We also show that in ghost and generalized ghost cosmologies, the growth factor [Formula: see text] rise front the values for an [Formula: see text]CDM universe. Finally, we constrain the model parameters by using the maximum likelihood analysis and a combined dataset of baryon acoustic oscillation (BAO) and OHD.

Generalized Ghost Dark Energy Model in the Framework of Quantum Cosmology for Different Scale Factor Choices

Generalized Ghost Dark Energy Model in the Framework of Quantum Cosmology for Different Scale Factor Choices

Effects of Low Anisotropy on Generalized Ghost Dark Energy in Galileon Gravity

The definition of the Galileon gravity form is extended to the Brans-Dicke theory. Given, the framework of the Galileon theory, the generalized ghost dark energy model in an anisotropic universe is investigated. We study the cosmological implications of this model. In particular, we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of this dark energy in Bianchi type I model. We also probe observational constraints by using the latest observational data on the generalized ghost dark energy models as the unification of dark matter and dark energy. In order to do so, we focus on observational determinations of the Hubble expansion rate (namely, the expansion history) H(z). As a result, we show the influence of the anisotropy (although low) on the evolution of the universe in the statefinder diagrams for Galileon gravity.

Anisotropic Cosmology with a Dilaton Field Coupled to Ghost Dark Energy

We study a dilaton scalar field coupled to ghost dark energy in an anisotropic universe. The evolution of dark energy, which dominates the universe, can be completely described by a single dilaton scalar field. This connection allows reconstructing the kinetic energy and also the dynamics of the dilaton scalar field according to the evolution of the energy density. Using the latest observational data, we obtain bounds on the ghost dark energy models and also on generalized dark matter and dark energy. For this, we investigate how the expansion history H(z) is determined by observational quantities. We calculate the evolution of density perturbations in the linear regime for both ghost and generalized ghost dark energy and compare the results with ΛCDM models. We discuss the justification of the generalized second law of thermodynamics in a Bianchi type-I universe. The obtained model is stable for large time intervals but is unstable at small times.

Dynamics of ghost scalar fields in Kaluza–Klein cosmology

In the present study, we discuss generalized ghost dark energy (GGDE) density and some scalar field dark energy (SFDE) models together with the Kaluza–Klein universe (KKU). Making use of this connection, we reconstruct in detail the dynamics of tachyon and quintessence type SFDE proposals. We show that the results we obtained are in consistent with the data presented by the Planck Collaboration. Additionally, we also reimplement dynamics of DBI (Dirac–Born–Infeld)-essence, k-essence (kinetic quintessence) and dilaton type SFDE models in a general form.