Abstract
We study a dark energy scenario in the presence of a tachyon field with potential and a barotropic perfect fluid. The cosmological dynamics crucially depends on the asymptotic behavior of the quantity . If is a constant, which corresponds to an inverse square potential , there exists one stable critical point that gives an acceleration of the Universe at late times. When asymptotically, we can have a viable dark energy scenario in which the system approaches an instantaneous critical point that dynamically changes with . If approaches infinity asymptotically, the Universe does not exhibit an acceleration at late times. In this case, however, we find an interesting possibility that a transient acceleration occurs in a regime where is smaller than of order unity.
- Received 25 November 2004
DOI:https://doi.org/10.1103/PhysRevD.71.043003
©2005 American Physical Society