Dark energy models in the ww{sup '} plane
Abstract
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{sup '} (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{sup '}<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 ww{sup '} plane. We also derive two new bounds for quintessence models in the ww{sup '} plane: the first is a general bound for any scalar field with a monotonic potential, while the second improves on the CaldwellLinder bound for tracker quintessence models. Observationally distinguishing barotropic models from quintessence models requires {sigma}(w{sup '}) < or approx. 1+w.
 Authors:
 Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
 Publication Date:
 OSTI Identifier:
 20776719
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.73.043502; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COSMOLOGY; EQUATIONS OF STATE; FLUID MECHANICS; NONLUMINOUS MATTER; POTENTIALS; SCALAR FIELDS; SOUND WAVES; VELOCITY
Citation Formats
Scherrer, Robert J. Dark energy models in the ww{sup '} plane. United States: N. p., 2006.
Web. doi:10.1103/PhysRevD.73.043502.
Scherrer, Robert J. Dark energy models in the ww{sup '} plane. United States. doi:10.1103/PhysRevD.73.043502.
Scherrer, Robert J. Wed .
"Dark energy models in the ww{sup '} plane". United States.
doi:10.1103/PhysRevD.73.043502.
@article{osti_20776719,
title = {Dark energy models in the ww{sup '} plane},
author = {Scherrer, Robert J.},
abstractNote = {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{sup '} (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{sup '}<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 ww{sup '} plane. We also derive two new bounds for quintessence models in the ww{sup '} plane: the first is a general bound for any scalar field with a monotonic potential, while the second improves on the CaldwellLinder bound for tracker quintessence models. Observationally distinguishing barotropic models from quintessence models requires {sigma}(w{sup '}) < or approx. 1+w.},
doi = {10.1103/PhysRevD.73.043502},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}

Important observables to reveal the nature of dark energy are the equation of state w and its time derivative in units of the Hubble time w{sup '}. Recently, it was shown that the simplest scalar field models of dark energy (quintessence) occupy rather narrow regions in the ww{sup '} plane. We extend the ww{sup '} plane to w<1 and derive bounds on w{sup '} as a function of w for tracker phantom dark energy. We also derive bounds on tracker kessence. The observational window for w{sup '} for w<1 is not narrow, {sigma}(w{sup '}) < or approx. 6(1+w)

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