Claudia Quercellini et al 2007 Class. Quantum Grav. 24 5413 doi:10.1088/0264-9381/24/22/006
Claudia Quercellini1, Marco Bruni1,2,3 and Amedeo Balbi1,2
Show affiliationsWe explore the possibility that a scalar field with appropriate Lagrangian can mimic a perfect fluid with an affine barotropic equation of state. The latter can be thought of as a generic cosmological dark component evolving as an effective cosmological constant plus a generalized dark matter. As such, it can be used as a simple, phenomenological model for either dark energy or unified dark matter. Furthermore, it can approximate (up to first order in the energy density) any barotropic dark fluid with arbitrary equation of state. We find that two kinds of Lagrangians for the scalar field can reproduce the desired behaviour: a quintessence-like with a hyperbolic potential, or a purely kinetic k-essence one. We discuss the behaviour of these two classes of models from the point of view of the cosmological background, and give some hints on their possible clustering properties.
04.20.Fy Canonical formalism, Lagrangians, and variational principles
95.30.Tg Thermodynamic processes, conduction, convection, equations of state
95.30.Sf Relativity and gravitation
95.35.+d Dark matter (stellar, interstellar, galactic, and cosmological)
83C25 Approximation procedures, weak fields
Issue 22 (21 November 2007)
Received 25 June 2007, in final form 3 September 2007
Published 24 October 2007
Claudia Quercellini et al 2007 Class. Quantum Grav. 24 5413
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