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Register a new userInteracting viscous ghost tachyon, K-essence and dilaton scalar field models of dark energy
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We study the correspondence between the interacting viscous ghost dark energy model with the tachyon, K-essence and dilaton scalar field models in the framework of Einstein gravity. We consider a spatially non-flat FRW universe filled with interacting viscous ghost dark energy and dark matter. We reconstruct both the dynamics and potential of these scalar field models according to the evolutionary behavior of the interacting viscous ghost dark energy model, which can describe the accelerated expansion of the universe. Our numerical results show that the interaction and viscosity have opposite effects on the evolutionary properties of the ghost scalar filed models.
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K-essence is a minimally-coupled scalar field whose Lagrangian density $mathcal{L}$ is a function of the field value $phi$ and the kinetic energy $X=frac{1}{2}partial_muphipartial^muphi$. In the thawing scenario, the scalar field is frozen by the large Hubble friction in the early universe, and therefore initial conditions are specified. We construct thawing k-essence models by generating Taylor expansion coefficients of $mathcal{L}(phi, X)$ from random matrices. From the ensemble of randomly generated thawing k-essence models, we select dark energy candidates by assuming negative pressure and non-growth of sub-horizon inhomogeneities. For each candidate model the dark energy equation of state function is fit to the Chevallier-Polarski-Linder parameterization $w(a) approx w_0+w_a(1-a)$, where $a$ is the scale factor. The thawing k-essence dark models distribute very non-uniformly in the $(w_0, w_a)$ space. About 90% models cluster in a narrow band in the proximity of a slow-roll line $w_aapprox -1.42 left(frac{Omega_m}{0.3}right)^{0.64}(1+w_0)$, where $Omega_m$ is the present matter density fraction. This work is a proof of concept that for a certain class of models very non-uniform theoretical prior on $(w_0, w_a)$ can be obtained to improve the statistics of model selection.
We investigate the holographic, new agegraphic and ghost dark energy models in the framework of fractal cosmology. We consider a fractal FRW universe filled with the dark energy and dark matter. We obtain the equation of state parameters of the selected dark energy models in the ultraviolet regime and discuss on their implications.
We are studying the mechanism of the cosmic model in the presence of GGPDE and matter in LRS Bianchi type-I space-time by the utilization of new holographic DE in Saez-Ballester theory. Here we discuss all the data for three scenarios, first is supernovae type Ia union data, second is SN Ia data in combination with BAO and CMB observations and third is combination with OHD and JLA observations. From this, we get a model of our universe, where its transit state from deceleration to acceleration phase. Here we have observed that the results yielded by cosmological parameters like $rho$ (energy density), EoS (equation of state), squared speed of sound $(v_s^2)$, $(omega_D-omega_D^{})$ and $(r-s)$ plane is compatible with the recent observational data. The $(omega_D-omega_D^{})$ trajectories in both thawing and freezing regions and the correspondence of the quintessence field with GGPD dark energy are discussed. Some physical aspects of the GGPDE models are also highlighted.
In this paper we revisit the dynamical dark energy model building based on single scalar field involving higher derivative terms. By imposing a degenerate condition on the higher derivatives in curved spacetime, one can select the models which are free from the ghost mode and the equation of state is able to cross the cosmological constant boundary smoothly, dynamically violate the null energy condition. Generally the Lagrangian of this type of dark energy models depends on the second derivatives linearly. It behaves like an imperfect fluid, thus its cosmological perturbation theory needs to be generalized. We also study such a model with explicit form of degenerate Lagrangian and show that its equation of state may cross -1 without any instability.
In this paper we study a novel means of coupling neutrinos to a Lorentz violating background k-essence field. We first look into the effect that k-essence has on the neutrino dispersion relation and derive a general formula for the neutrino velocity in the presence on a k-essence background. The influence of k-essence coupling on neutrino oscillations is then considered. It is found that a non-diagonal k-essence coupling leads to an oscillation length that goes like lambda sim E^{-1} where E is the energy. This should be contrasted with the lambda sim E dependence seen in the standard mass-induced mechanism of neutrino oscillations. While such a scenario is not favored experimentally, it places constraints on the interactions of the neutrino with a cosmological k-essence scalar background by requiring it to be flavor diagonal. All non-trivial physical effects discussed here require the speed of sound to be different from the speed of light and hence are primarily a consequence of Lorentz violation.
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