2004/02/29 by Robert J. Scherrer · 22 citations
Physics and Astronomy · #Astrophysics #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Dark matter #Energy (signal processing) #Equation of state #Function (biology) #Geometry #Kinetic energy #Luminosity distance #Mathematical physics #Particle physics #Physics #Quantum mechanics #Relativity and Gravitational Theory #Scalar (mathematics) #Scalar field #Scaling #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevlett.93.011301
published as Phys.Rev.Lett. 93 (2004) 011301 · 5 pages, no figures, discussion and references added, to appear in Physical Review Letters
arxiv created 2004/05/06 · openalex publication_date 2004/06/30 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We examine k-essence models in which the Lagrangian p is a function only of the derivatives of a scalar field \ensuremathφ and does not depend explicitly on \ensuremathφ. The evolution of \ensuremathφ for an arbitrary functional form for p can be given in terms of an exact analytic solution. For quite general conditions on the functional form of p, such models can evolve to a state characterized by a density \ensuremathρ scaling with the scale factor a as \ensuremathρ=\ensuremathρ0+\ensuremathρ1(a/a0)^\ensuremath-3, but with a sound speed cs2\ensuremath≪1 at all times. Such models can serve as a unified model for dark matter and dark energy, while avoiding the problems of the generalized Chaplygin gas models, which are due to a non-negligible sound speed in these models. A dark-energy component with cs\ensuremath≪1 serves to suppress cosmic microwave background fluctuations on large-angular scales.