2005/09/30 by Robert J. Scherrer · 121 citations
Environmental Science · Mathematics · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Astrophysics #Barotropic fluid #Climate variability and models #Cosmology #Cosmology and Gravitation Theories #Dark energy #Geometry #Mathematical physics #Mathematics #Physics #Quintessence #Scalar (mathematics) #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.73.043502
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 73(4) (American Physical Society) · 5 pages, 3 figures, references and discussion added, to appear in Phys. Rev. D
arxiv created 2006/01/31 · openalex publication_date 2006/02/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We examine the behavior of dark energy models in the plane defined by w (the equation of state parameter for the dark energy) and w^\ensuremath' (the derivative of w with respect to the logarithm of the scale factor). For nonphantom barotropic fluids with positive squared sound speed, we find that w^\ensuremath'<3w(w+1), the opposite of the bound on quintessence models previously derived by Caldwell and Linder. Thus, these barotropic models and quintessence models for the dark energy occupy disjoint regions in the w\ensuremath-w^\ensuremath' plane. We also derive two new bounds for quintessence models in the w\ensuremath-w^\ensuremath' plane: the first is a general bound for any scalar field with a monotonic potential, while the second improves on the Caldwell-Linder bound for tracker quintessence models. Observationally distinguishing barotropic models from quintessence models requires \ensuremathσ(w^\ensuremath')\ensuremath\lesssim1+w.