Dark-energy evolution across the cosmological-constant boundary
By R. Caldwell, M. Doran. 2005
145 citations recorded by the source corpus.
We explore the properties of dark-energy models for which the equation of state, w, defined as the ratio of pressure to energy density, crosses the cosmological-constant boundary w=-1. We adopt an empirical approach, treating the dark energy as an uncoupled fluid or a generalized scalar field. We describe the requirements for a viable model, in terms of the equation of state and sound speed. A generalized scalar field cannot safely traverse w=-1, although a pair of scalars with w>-1 and w<-1 will work. A fluid description with a well-defined sound speed can also cross the boundary. Contrary to expectations, such a crossing model does not instantaneously resemble a cosmological constant at the moment w=-1 since the density and pressure perturbations do not necessarily vanish. But because a dark energy with w<-1 dominates only at very late times, and because the dark energy is not generally prone to gravitational clustering, then crossing the cosmological-constant boundary leaves no distinct imprint.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/48c06066603bdbd9e3b3768abcdce0a573cea996
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In Astronomy and Astrophysics
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Citations in the corpus
- Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity (2014, background): “Scalar perturbations dominate at linear scales and, in principle, all one needs to do is to relate the two scalar gravitational potentials to the matter distribution through some sort of parameterisation involving two functions of both scale and time [18–20].”
- The effective theory of quintessence: the w < 1 side unveiled (2008, background): “However, there is no real pathology in crossing this line, besides the fact that for wQ < −1 short-scale gradient instabilities must be stabilized [5, 6].”
- Dust of dark energy (2010, result): “[40] R.”