Phantom Dark Energy Models with Negative Kinetic Term
Abstract
We examine phantom dark energy models derived from a scalar field with a negative kinetic term for which V(phi) approaches infinity asymptotically. All such models can be divided into three classes, corresponding to an equation of state parameter w with asymptotic behavior w -> -1, w -> w_0 < -1, and w -> infinity. We derive the conditions on the potential V(phi) which lead to each of these three types of behavior. For models with w -> -1, we derive the conditions on V(phi) which determine whether or not such models produce a future big rip. Observational constraints are derived on two classes of these models: power-law potentials with V(phi) = lambda phi^alpha (with alpha positive or negative) and exponential potentials of the form V(phi) = beta e^{lambda phi^alpha}. It is shown that these models spend more time in a state with Omega_m ~ Omega_phi than do corresponding models with a constant value of w, thus providing a more satisfactory solution to the coincidence problem.
Keywords
Cite
@article{arxiv.astro-ph/0606735,
title = {Phantom Dark Energy Models with Negative Kinetic Term},
author = {Jens Kujat and Robert J. Scherrer and A. A. Sen},
journal= {arXiv preprint arXiv:astro-ph/0606735},
year = {2009}
}
Comments
9 pages, 11 figures, minor clarifications added, to appear in Phys. Rev. D