arXiv subjects

Xiang-Ting Gao

Publications and source records attributed to Xiang-Ting Gao.

3 recordsLinked to original sources

arXiv2011

Phase-space analysis of a class of k-essence cosmology

We perform a detailed phase-space analysis of a class of k-essence cosmology. We find the critical points can be divided into three classes: points unstable but the model stable, both points and the model stable, points stable but the model unstable. Like the case of points unstable but the model stable, the case of points stable but the model unstable is not relevant from a cosmological point of view, though they can be late-time attractors for the universe. So in order to study the possible final state of the universe, it is important to investigate not only the stability of the critical points but also the stability of the model. The case of both points and the model stable can further be divided into two classes: points only presenting decelerating phases and points at which all decelerating, constant-speed, and accelerating phases can appear; the final state of the universe dependents on the potential.

gr-qc↗

arXiv2010

Restrictions on purely kinetic k-essence

We restrict purely kinetic k-essence. Assuming the equation of state is a power law of the kinetic energy: $w=w_0X^α$, to obtain accelerated phases, we must have $α>0$ as one of necessary conditions, constrained from the conditions for stability and causality, and the k-essence must behave like phantom. We also study the evolutions of the equation of state and the speed of sound with numerical simulation.

gr-qc↗

arXiv2010

Geometrical diagnostic for purely kinetic k-essence dark energy

Geometrical diagnostic, involving the statefinder $\{r,s\}$ and $Om(x)$, is widely used to discriminate different dark energy models. We apply the statefinder $\{r,s\}$ and $Om(x)$ to purely kinetic k-essence dark energy model with Dirac-Born-Infeld-like Lagrangian which can be considered as scalar field realizations of Chaplygin gas. We plot the evolution trajectories of this model in the statefinder parameter-planes and $Om(x)$ parameter-plane. We find that the statefinder $\{r,s\}$ and $Om(x)$ fail to distinguish purely kinetic k-essence model from $Λ$CDM model at 68.3% confidence level for $z\ll 1$.

gr-qc↗