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- Title
GHOST COSMOLOGY:: EXACT SOLUTIONS, TRANSITIONS BETWEEN STANDARD COSMOLOGIES AND GHOST EVOLUTION.
- Authors
Axel Krause; Siew-Phang Ng
- Abstract
The recently proposed infrared modification of gravity through the introduction of a ghost scalar field results in a number of interesting cosmological and phenomenological implications. In this paper, we derive the exact cosmological solutions for a number of scenarios where at late stages, the ghost behaves like dark matter, or dark energy. The full solutions provide information about the nonlinear regime beyond the asymptotic analysis presented in the literature. The generic feature is that these ghost cosmologies give rise to smooth transitions between radiation dominated phases (or more general power-law expansions) at early epochs and ghost dark matter resp. ghost dark energy dominated late epochs. The current age of our universe places us right at the nonlinear transition phase. By studying the evolution backwards in time, we find that the dominance of the ghost over ordinary baryonic matter and radiative contributions persists back to the earliest times such that the Friedmann–Robertson–Walker geometry is dictated to a good approximation by the ghost alone. We also show that a Jeans instability arises in the ghost dark energy scenario at late times, while it is absent in the ghost dark matter scenario.
- Subjects
SCALAR field theory; FORCE &; energy; GEOMETRY; GRAVITY; GEOPHYSICS; RADIATION
- Publication
International Journal of Modern Physics A: Particles & Fields; Gravitation; Cosmology; Nuclear Physics, 2006, Vol 21, Issue 5, p1091
- ISSN
0217-751X
- Publication type
Article
- DOI
10.1142/S0217751X0602516X