Narrow Results

We assume that universe is dominated by non-relativistic matter and tachyon field and reconstruct the potential of tachyon field directly from the effective equation of state (EOS) of dark energy. We apply the method to four known parametrizations of equation of state and discuss the general features of the resulting potentials.

In this paper we study the statefinder parameters for the tachyon dark energy model. There are two kinds of stable attractor solutions in this model. The statefinder diagrams characterize the properties of the tachyon dark energy model. Our results show that the evolving trajectories of the attractor solutions lie in the total region and pass through the LCDM fixed point, which is different from other dark energy model.

In this paper we study the statefinder parameters for the coupled tachyon dark energy model which has two types of stable scaling solutions. It is found that the evolving trajectories of the solutions are different in the statefinder parameters plane. These trajectories lie in the two regions r > 1, s < 0 and r < 1, s > 0, and pass through the LCDM fixed point. So, through the statefinder diagnostic, we not only characterize the properties of the coupled tachyon dark energy model, but also show the difference from other dark energy model.

In this paper we investigate a tachyon field model in cosmology, provided its interaction with the quintessence or phantom fields. The model takes into account this interaction beyond the usual approach, in which the interaction is phenomenologically described by the energy flow between the matter components. In our model, the interaction of tachyon field with a canonical scalar field is taken into account through the interaction potential in the total Lagrangian of the system, like in the case of two or more canonical scalar fields. We obtain the different types of exact solution for the model by employing the so-called "first order formalism" procedures.

In this paper, we have researched tachyon field, k-essence and quintessence dark energy (DE) models for Friedmann–Robertson–Walker (FRW) universe with varying G and $\mathrm{\Lambda }$ in f(R, T) gravitation theory. The theory of f(R, T) is proposed by Harko et al. [Phys. Rev. D84, 024020, 2011]. In this theory, R is the Ricci scalar and T is the trace of energy–momentum tensor. For the solutions of field equations, we have used linearly varying deceleration parameter (LVDP), the equation of state (EoS) and the ratio between $\mathrm{\Lambda }$ and Hubble parameter. Also, we have discussed some physical behavior of the models with various graphics.

In this research, we have investigated tachyon and $k$-essence dark energy (DE) candidates with varying $G$ and $\mathrm{\Lambda }$ for Marder universe in $f(R,T)$ gravitation theory [Harko et al., Phys. Rev. D84, 024020 (2011)]. Here, $f(R,T)$ is the arbitrary function of Ricci scalar ($R$) and the trace of $T_{ik}$. To solve $f(R,T)$ gravity field equations, three different approximations have been used such as cosmological term, equation of state (EoS) parameter and the anisotropy feature of Marder universe. Also, we have discussed some physical results with various graphics.