New mechanism to cross the phantom divide
arXiv:1008.4421 · doi:10.1140/epjc/s10052-011-1660-z
Abstract
Recently, type Ia supernovae data appear to support a dark energy whose equation of state crosses -1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the equation of state to cross the phantom divide by a scalar field in the gravity with an additional inverse power-law term of Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the phantom divide is obtained. Some analytical solutions with or are obtained. A minimal coupled scalar with different potentials, including quadratic, cubic, quantic, exponential and logarithmic potentials are investigated via numerical methods, respectively. All these potentials lead to the crossing behavior. We show that it is a robust result which is hardly dependent on the concrete form of the potential of the scalar.
11 pages, 5 figs, v3: several references added, to match the published version
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