Interacting Entropy-Corrected New Agegraphic K-essence, Tachyon and Dilaton Scalar Field Models in?Non-flat Universe

We consider the new agegraphic dark energy model with the help of the quantum corrections to the entropy-area relation in the setup of loop quantum gravity. Employing this new form of dark energy so called entropy-corrected new agegraphic dark energy (ECNADE), we investigate the model of interacting dark energy and derive its equation of state (EoS). We study the correspondence between the K-essence, tachyon and dilaton scalar fields with the interacting (ECNADE)in the non-flat FRW universe. Moreover, we reconstruct the corresponding scalar potentials which describe the dynamics of the scalar field.     

New Agegraphic Dark Energy in Brans-Dicke Theory

In this paper, we investigate the new agegraphic dark energy model in the framework of Brans-Dicke theory, which is a natural extension of the Einstein's general relativity. In this framework the form of the new agegraphic dark energy density takes as ρ_q =3n² φ(t) η^-2, where η is the conformalage of the universe and φ(t) is the Brans-Dicke scalar field representing the inverse of the time-variable Newton's constant. We derive the equation of state of the new agegraphic dark energy and the deceleration parameter of the universe in the Brans-Dicke theory. It is very interesting to find that in the Brans-Dicke theory the agegraphic dark energy realizes quintom-like behavior,i.e., its equation of state crosses the phantom divide w=-1 duringthe evolution. We also compare the situation of the agegraphic darkenergy model in the Brans-Dicke theory with that in the Einstein'stheory. In addition, we discuss the new agegraphic dark energy modelwith interaction in the framework of the Brans-Dicke theory.     

Interacting Entropy-Corrected Agegraphic-Tachyon Dark Energy

Motivated by recent work of Sheykhi (Phys. Lett. B 682:329, 2010), we generalize this work to agegraphic tachyon models of dark energy with entropy correction terms arising from loop quantum gravity. We establish a connection between the entropy-corrected agegraphic dark energy and the tachyon scalar field in a universe with spacial curvature and reconstruct the potential and the dynamics of the tachyon scalar field which describe the tachyon cosmology. The cosmological implications of the entropy-corrected agegraphic dark energy models are also discussed.     

The Generalized Second Law for the Interacting New Agegraphic Dark Energy in a Non-flat FRW Universe Enclosed by the Dynamical Apparent Horizon

We investigate the validity of the generalized second law of gravitational thermodynamics on the dynamical apparent horizon in a non-flat FRW universe containing the interacting new agegraphic dark energy with dark matter. We show that for this model, the equation of state parameter can cross the phantom divide line. We also present that for the selected model under thermal equilibrium with the Hawking radiation, the generalized second law is always satisfied throughout the history of the universe. Whereas, the evolution of the entropy of the universe and dynamical apparent horizon, separately, depends on the equation of state parameter of the interacting new agegraphic dark energy model.     

A Dark Energy Model with Generalized Uncertainty Principle in the Emergent, Intermediate and Logamediate Scenarios of the Universe

This work is motivated by the work of Kim et al. (Mod. Phys. Lett. A 23:3049, 2008), which considered the equation of state parameter for the new agegraphic dark energy based on generalized uncertainty principle coexisting with dark matter without interaction. In this work, we have considered the same dark energy interacting with dark matter in emergent, intermediate and logamediate scenarios of the universe. Also, we have investigated the statefinder, kerk and lerk parameters in all three scenarios under this interaction. The energy density and pressure for the new agegraphic dark energy based on generalized uncertainty principle have been calculated and their behaviors have been investigated. The evolution of the equation of state parameter has been analyzed in the interacting and non-interacting situations in all the three scenarios. The graphical analysis shows that the dark energy behaves like quintessence era for logamediate expansion and phantom era for emergent and intermediate expansions of the universe.     

Interacting agegraphic dark energy

A new dark energy model, named “agegraphic dark energy”, has been proposed recently, based on the so-called Károlyházy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegraphic dark energy model and holographic dark energy model. The similarity and difference between agegraphic dark energy and holographic dark energy are also discussed.     

Role of Entropy-Corrected New Agegraphic Dark Energy in Hořava-Lifshitz Gravity

In this work, we have considered the entropy-corrected new agegraphic dark energy (ECNADE) model in Ho?ava-Lifshitz gravity in FRW universe. We have discussed the correspondence between ECNADE and other dark energy models such as DBI-essence, Yang-Mills dark energy, Chameleon field, Non-linear electrodynamics field and hessence dark energy in the context of Ho?ava-Lifshitz gravity and reconstructed the potentials and the dynamics of the scalar field theory which describe the ECNADE.     

Cosmological Implications of Interacting Polytropic Gas Dark Energy Model in Non-flat Universe

The polytropic gas model is investigated as an interacting dark energy scenario. The cosmological implications of the model including the evolution of EoS parameter w _Λ, energy density Ω_Λ and deceleration parameter q are investigated. We show that, depending on the parameter of model, the interacting polytropic gas can behave as a quintessence or phantom dark energy. In this model, the phantom divide is crossed from below to up. The evolution of q in the context of polytropic gas dark energy model represents the decelerated phase at the early time and accelerated phase later. The singularity of this model is also discussed. Eventually, we establish the correspondence between interacting polytropic gas model with tachyon, K-essence and dilaton scalar fields. The potential and the dynamics of these scalar field models are reconstructed according to the evolution of interacting polytropic gas.     

Generalized Chaplygin Gas Model as a New Agegraphic Dark Energy in Non-flat Universe

In this paper we consider a correspondence between the new agegraphic dark energy density and generalized Chaplygin gas energy density in non-flat FRW universe. Then we reconstruct the potential and the dynamics of the scalar field which describe the generalized Chaplygin cosmology.     

Correspondence Between Interacting New Agegraphic and Tachyon Dark Energy Models

In this paper we consider a correspondence between the interacting new agegraphic dark energy density and tachyon energy density in non-flat universe. Then we reconstruct the potential and the dynamics of the tachyon field which describe tachyon cosmology.     

Quintessence Reconstruction of Interacting HDE in a Non-Flat Universe

In this paper we consider quintessence reconstruction of interacting holographic dark energy in a non-fiat background. As system＇s IR cutoff we choose the radius of the event horizon measured on the sphere of the horizon, defined as L = at（t）. To this end we construct a quintessence model by a real, single scalar field. Evolution of the potential, V（φ）, as well as the dynamics of the scalar field, φ, is obtained according to the respective holographic dark energy. The reconstructed potentials show a cosmological constant behavior for the present time. We constrain the model parameters in a fiat universe by using the observational data, and applying the Monte Carlo Markov chain simulation. We obtain the best fit values of the holographic dark energy model and the interacting parameters as c=1.0576-0.6632-0.6632^＋0.3010＋0.3052 and ζ =0.2433-0.2251-.2251^＋0.6373＋0.6373 , respectively. From the data fitting results we also find that the model can cross the phantom line in the present universe where the best fit value of the dark energy equation of state is WD=-1.2429.     

Interacting New Agegraphic Viscous Dark Energy with Varying <Emphasis Type="Italic">G</Emphasis>

We consider the new agegraphic model of dark energy with a varying gravitational constant, G, in a non-flat universe. We obtain the equation of state and the deceleration parameters for both interacting and noninteracting new agegraphic dark energy. We also present the equation of motion determining the evolution behavior of the dark energy density with a time variable gravitational constant. Finally, we generalize our study to the case of viscous new agegraphic dark energy in the presence of an interaction term between both dark components.     

Interacting entropy-corrected new agegraphic dark energy in Brans–Dicke cosmology

Motivated by a recent work of one of us (Sheykhi in Phys Rev D 81: 023525, 2010), we extend it by using quantum (or entropy) corrected new agegraphic dark energy in the Brans–Dicke cosmology. The correction terms are motivated from the loop quantum gravity which is one of the competitive theories of quantum gravity. Taking the non-flat background spacetime along with the conformal age of the universe as the length scale, we derive the dynamical equation of state of dark energy and the deceleration parameter. An important consequence of this study is the phantom divide scenario with entropy-corrected new agegraphic dark energy. Moreover, we assume a system of dark matter, radiation and dark energy, while the later interacts only with dark matter. We obtain some essential expressions related with dark energy dynamics. The cosmic coincidence problem is also resolved in our model.     

Restoring New Agegraphic Dark Energy in RS II Braneworld

Motivated by recent works (Saridakis in Phys. Lett. B 660:138, 2008; Sheykhi in Int. J. Mod. Phys. D 19(3):305, 2010), we investigate the new agegraphic model of dark energy in the framework of RS II braneworld. We also include the case of variable gravitational constant G in our model. Moreover, we reconstruct the potential and the dynamics of the quintessence, tachyon, K-essence and dilaton scalar field models according to the evolutionary behavior of the new agegraphic dark energy model in RS II braneworld cosmology including varying G.     

An Interacting Two-Fluid Scenario for Quintom Dark Energy

The Quintom dark energy is a proposal that explains the recent observations that mildly favor the equation of state of dark energy ω crossing -1 near the past. The Quintom model is often constructed by two scalar fields, where one is the quintessence feld and another is the phantom field. The cosmological implication of the coupling of the two fields of the dark energy is out of question worth investigating. However, the consideration of the coupling in the field scenario is somewhat complex thus we propose an interacting two-fluid Quintom scenario for simplicity. The interaction between the two components is parametrized by a constant 71 in this scenario. The cosmological implications of this parametrization are investigated in detail in this paper. Also, a diagnostic for this model is performed by using the statefinder pairs {s, r} and {q, r}.     

Agegraphic dark energy as a quintessence

Recently, a dark energy model characterized by the age of the universe, dubbed “agegraphic dark energy”, was proposed by Cai. In this paper, a connection between the quintessence scalar-field and the agegraphic dark energy is established, and accordingly, the potential of the agegraphic quintessence field is constructed.     

Exact solution of phantom dark energy model

We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term.By assuming a particular relation between the time derivative of the phantom field and the Hubble function,an exact solution of the model is constructed.Absence of the ’big rip’ singularity is shown explicitly.We then derive special features of phantom dark energy model and show that its predictions are consistent with all astrophysical observations.     

A Note on Equivalence Among Various Scalar Field Models of Dark Energies

In this work, we have tried to find out similarities between various available models of scalar field dark energies (e.g., quintessence, k-essence, tachyon, phantom, quintom, dilatonic dark energy, etc). We have defined an equivalence relation from elementary set theory between scalar field models of dark energies and used fundamental ideas from linear algebra to set up our model. Consequently, we have obtained mutually disjoint subsets of scalar field dark energies with similar properties and discussed our observation.