A new model of dark energy namely "ghost dark energy model" has recently been suggested to interpret the positive acceleration of cosmic expansion. The energy density of ghost dark energy is proportional to the hubble parameter. In this paper we perform the statefinder diagnostic tool for this model both in flat and non-flat universe. We discuss the dependency of the evolutionary trajectories in $s-r$ and $q-r$ planes on the interaction parameter between dark matter and dark energy as well as the spatial curvature parameter of the universe. Eventually, in the light of SNe+BAO+OHD+CMB observational data, we plot the evolutionary trajectories in $s-r$ and $q-r$ planes for the best fit values of the cosmological parameters and compare the interacting ghost model with other dynamical dark energy models. We show that the evolutionary trajectory of ghost dark energy in statefinder diagram is similar to holographic dark energy model. It has been shown that the statefinder location of $Λ$CDM is in good agreement with observation and therefore the dark energy models whose current statefinder values are far from the $Λ$CDM point can be ruled out.
Non-minimally coupled scalar field models of dark energy are equivalent to an interacting quintessence in the Einstein's frame. Considering two special important choices of the potential of the scalar field, i.e. nearly flat and thawing potential, one has an analytical expression for the equation of state parameter as a function of the density parameter of the scalar field for any choice. Here we investigate the non-minimal quintessence model by applying the method of statefinder diagnosis to it and plotting the evolutionary trajectories of the statefinder parameters.
In this paper, we study the possible connections among different Spinor Quintom Dark Energy (DE) models by the aid of duality. Then we apply the statefinder diagnostic to these models. By this diagnostic pair {$\{r,s\}$}, we differentiate one Quintom DE model from the others in a model independent manner. A class of evolutionary trajectories of these Spinor Quintom models are presented in the statefinder parameter planes. We also obtain the current locations of the parameters $r$ and $s$, and these locations correspond to different models in statefinder parameter planes theoretically.
In this paper, the generalized second law (GSL) of thermodynamics and entropy is revisited in the context of cosmological models with bouncing behavior such as chameleon cosmology where the boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. From a thermodynamic point of view, to link between thermodynamic and geometric parameters in cosmological models, we introduce "entropy rate of change multiplied by the temperature" as a model independent thermodynamic state parameter together with the well known $\{r,s \}$ statefinder to differentiate the dark energy mod…
Many dark energy (DE) models have been proposed, in recent years, to explain acceleration of the Universe expansion. It seems necessary to discriminate the various DE models in order to check the viability of each model. Statefinder diagnostic is a useful method which can differentiate various DE models. In this paper, we investigate the statefinder diagnosis parameters for the holographic dark energy (HDE) model in two cosmological setup. First, we study statefinder diagnosis for HDE in the context of flat Friedmann-Robertson-Walker (FRW) Universe in Einstein gravity. Then, we extend our stud…
In this work, we have considered the recently proposed new Tsallis Agegraphic Dark Energy model (NTADE) (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 $δ$. The NTADE model shows the current phase transition of the Universe from decelerated to accelerated phase. The NTADE EoS parameter shows a rich behaviour as it can be quintessence-like or phantom-like depending on the value of $δ$. For discriminating the NTADE model from $Λ$CDM, we have plotted the statefinder parameters $r(z)$, $s(z)$ a…
The generalized Chaplygin gas (GCG) model in spatially flat universe is investigated. The cosmological consequences led by GCG model including the evolution of EoS parameter, deceleration parameter and dimensionless Hubble parameter are calculated. We show that the GCG model behaves as a general quintessence model. The GCG model can also represent the pressureless CDM model at the early time and cosmological constant model at the late time. The dependency of transition from decelerated expansion to accelerated expansion on the parameters of model is investigated. The statefinder parameters $r$…
Exploring the accelerated expansion of the universe, we investigate the generalized ghost dark energy (GGDE) model from the statefinder diagnosis analysis in a flat FRW universe. First we calculate the cosmological evolution and statefinder trajectories for non-interacting case and then extend this work by considering the interaction between dark matter and dark energy components. We show that in the non-interacting case the phantom line can not be crossed and also he evolutionary trajectories of model in $s-r$ plane can not be discriminated. It has been shown that the present location of mode…
In this paper, we investigate cosmological consequences of a scenario for recently reported accelerated expansion of the Universe, in which the generalized Chaplygin gas (GCG) along with the baryonic matter are responsible for this observed phenomenon. In the present model, we employ an isotropic and homogeneous FLRW space time in the framework of $f(R,T)$ theory of gravity. In $f(R,T)$ gravity, the conservation of energy-momentum tensor (EMT) leads to a constraint equation which enforces us to use some specific forms of type $f(R,T)=g(R)+h(T)$. In this work we choose $g(R)=R$. We consider thr…
The proposal of pilgrim dark energy is based on the speculation that phantom-like dark energy possesses enough resistive force to preclude the black hole formation in the later universe. We explore this phenomenon by assuming the generalized ghost version of pilgrim dark energy. We find that most of the values of the interacting ($ξ^2$) as well as pilgrim dark energy ($u$) parameters push the equation of state parameter towards phantom region. The squared speed of sound shows that this model remains stable in most of the cases of $ξ^2$ and $u$. We also develop $ω_Λ-ω'_Λ$ plane and observe that…
Subject of our study it is the accelerated expansion of the large scale universe, where a varying ghost dark energy can take the role of the dark energy. The model of the varying ghost dark energy considered in this work it is a phenomenological modification of the ghost dark energy. Recently, three other phenomenological models of the varying ghost dark energy have been suggested and the model considered in this work will complete the logical chain of considered modifications. The best fit of theoretical results to the luminosity distance, has been used to obtain preliminary constraints on th…
This work is based on pilgrim dark energy conjecture which states that phantom-like dark energy possesses the enough resistive force to preclude the formation of black hole. The non-flat geometry is considered which contains the interacting generalized ghost pilgrim dark energy with cold dark matter. Some well-known cosmological parameters (evolution parameter ($ω_Λ$) and squared speed of sound) and planes ($ω_Λ$-$ω_Λ'$ and statefinder) are constructed in this scenario. The discussion of these parameters is totally done through pilgrim dark energy parameter ($u$) and interacting parameter ($d^…
The illustration of cosmic acceleration under two interacting dark energy models (pilgrim dark energy with Granda and Oliveros cutoff and its generalized ghost version) in DGP braneworld framework is presented. In the current scenario, the equation of state parameter, deceleration parameter, $ω_{D}-ω'_{D}$ plane and statefinder diagnosis are investigated. The equation state parameter behave-like phantom era of the universe. The deceleration parameter depicts the accelerated expansion of the universe in both models. The cosmological planes like $ω_{D}-ω'_{D}$ and statefinder corresponds to $Λ$C…
In this paper, we have used the state finder hierarchy for Barrow holographic dark energy (BHDE) model in the system of the FLRW Universe. We apply two DE diagnostic tools to determine $ΛBHDE$ model to have various estimations of $\triangle$. The first diagnostic tool is the state finder hierarchy in which we have studied $S^{(1)}_{3}$ $S^{(1)}_{4}$, $S^{(2)}_{3}$ $S^{(2)}_{4}$ and second is the composite null diagnostic (CND) in which the trajectories ( $S^{(1)}_{3} - ε$), ($S^{(1)}_{4}-ε$), ($S^{(2)}_{3}-ε$)($S^{(2)}_{4}-ε$) are discussed, where $ε$ is fractional growth parameter. The infrar…
In 2000, Giorgi Dvali, Gregory Gabadadze and Massimo Porrati (Dvali et al. 2000) was proposed a new braneworld model named as DGP model, having two branches with $(ε=+1)$ and $(ε=-1)$. Former one $(~ε=+1)$ known as the accelerating branch, i.e. accelerating phase of the universe can be explained without adding cosmological constant or Dark energy, whereas later one represents the decelerating branch. Here we have investigated the behavior of decelerating branch $(i.e.~ε=-1)$ of DGP model with Generalized Ghost Dark Energy (GGDE). Aim of our study to find a stable solution of the universe in DG…
We investigate the ghost model of dark energy in the framework of DGP braneworld. We explore the cosmological consequences of this model by determining the equation of state parameter, $ω_D$, the deceleration and the density parameters. We also examine the stability of this model by studying the squared of the sound speed in the presence/absence of interaction term between dark energy and dark matter. We find out that in the absence of interaction between two dark sectors of the Universe we have $ω_D\rightarrow -1$ in the late time, while in the presence of interaction $ω_D$ can cross the phan…
In this paper we extend the form of interaction term into the non-linear regime in the ghost dark energy model. A general form of non-linear interaction term is presented and cosmic dynamic equations are obtained. Next, the model is detailed for two special choice of the non-linear interaction term. According to this the universe transits at suitable time ($z\sim 0.8$) from deceleration to acceleration phase which alleviate the coincidence problem. Squared sound speed analysis revealed that for one class of non-linear interaction term $v_s^2$ can gets positive. This point is an impact of the n…
We consider the cosmological dynamics of the cubic Galileon field model interacting with dark matter, where the interaction between the cosmic dark sectors is proportional to Hubble parameter and dark energy density. The background field equations are converted into an autonomous dynamical system of first order equations using suitable dimensionless variables. The fixed points are determined and their stability analyzed by means of the eigenvalue method. The analysis of the stability of the fixed points along that of the avoidance of ghosts and Laplacian instabilities implies negative coupling…
Rényi Holographic Dark Energy (RHDE) Models has been studied in different dimensions considering a flat FRW metric, subsequently exploring the nature of evolution of different cosmological parameters. It is seen that the number of dimensions affect the evolution of the cosmological parameters and the transition of the universe from decelerating to accelerating phase. The statefinder diagnosis has been performed and it is seen that the model corresponds to the $ΛCDM$ model for the present and future universe.
Stability analysis of agegraphic dark energy in Brans-Dicke theory is presented in this paper. We constrain the model parameters with the observational data and thus the results become broadly consistent with those expected from experiment. Stability analysis of the model without best fitting shows that universe may begin from an unstable state passing a saddle point and finally become stable in future. However, with the best fitted model, There is no saddle intermediate state. The agegraphic dark energy in the model by itself exhibits a phantom behavior. However, contribution of cold dark mat…
In this work we explore under a holographic approach the dark energy - dark matter interaction in a non-flat Friedmann-Lemaitre-Robertson-Walker spacetime, with a cut-off for the dark energy component given in terms of the Hubble scale. Based on results coming from the use of observational data, we consider a positive interaction $Q$-term together with a Chevallier-Polarsky-Linder type parametrization for the coincidence parameter, we realize that the model admits a Type III future singularity, in this singular universe we have that for a null value of the curvature parameter its scale factor …
