skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Power-law parametrized quintessence model

Abstract

We propose a simple power-law parametrized quintessence model with time-varying equation of state and obtain corresponding quintessence potential of this model. This model is compared with Supernova Type Ia (SNIa) Gold sample data, size of baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), the position of the acoustic peak from the CMB observations and structure formation from the 2dFGRS survey and put constrain on the parameters of model. The parameters from the best fit indicates that the equation of state of this model at the present time is w{sub 0}=-1.40{sub -0.65}{sup +0.40} at 1{sigma} confidence level. Finally we calculate the age of universe in this model and compare it with the age of old cosmological objects.

Authors:
 [1];  [1];  [2]
  1. Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)
  2. (Iran, Islamic Republic of)
Publication Date:
OSTI Identifier:
20935212
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevD.75.023512; (c) 2007 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; BARYONS; COSMOLOGICAL MODELS; EQUATIONS OF STATE; NONLUMINOUS MATTER; SUPERNOVAE; UNIVERSE

Citation Formats

Rahvar, Sohrab, Movahed, M. Sadegh, and Institute for Studies in Theoretical Physics and Mathematics, P.O. Box 19395-5531, Tehran. Power-law parametrized quintessence model. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.023512.
Rahvar, Sohrab, Movahed, M. Sadegh, & Institute for Studies in Theoretical Physics and Mathematics, P.O. Box 19395-5531, Tehran. Power-law parametrized quintessence model. United States. doi:10.1103/PHYSREVD.75.023512.
Rahvar, Sohrab, Movahed, M. Sadegh, and Institute for Studies in Theoretical Physics and Mathematics, P.O. Box 19395-5531, Tehran. Mon . "Power-law parametrized quintessence model". United States. doi:10.1103/PHYSREVD.75.023512.
@article{osti_20935212,
title = {Power-law parametrized quintessence model},
author = {Rahvar, Sohrab and Movahed, M. Sadegh and Institute for Studies in Theoretical Physics and Mathematics, P.O. Box 19395-5531, Tehran},
abstractNote = {We propose a simple power-law parametrized quintessence model with time-varying equation of state and obtain corresponding quintessence potential of this model. This model is compared with Supernova Type Ia (SNIa) Gold sample data, size of baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), the position of the acoustic peak from the CMB observations and structure formation from the 2dFGRS survey and put constrain on the parameters of model. The parameters from the best fit indicates that the equation of state of this model at the present time is w{sub 0}=-1.40{sub -0.65}{sup +0.40} at 1{sigma} confidence level. Finally we calculate the age of universe in this model and compare it with the age of old cosmological objects.},
doi = {10.1103/PHYSREVD.75.023512},
journal = {Physical Review. D, Particles Fields},
number = 2,
volume = 75,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • We argue that the quantization of Chodos, Jaffe, Johnson, Thorn, and Weisskopf (CJJTW) of the bag model in two dimensions is inappropriate for considerations of locality and we present a new quantization in which the parametrization is fixed by positivity. The CJJTW operator algebra is obtained as a subalgebra of an extended system. A boundary regularization procedure is introduced and a local phi (x) operator having cutoff-independent matrix elements is defined. Boundary fluctuation effects are finite. We calculate an example of bag scattering in an external field and show that the crossed-channel bag-pair production and annihilation amplitudes contain only thosemore » singularities associated with bag fission. Nontrivial light-cone commutators are calculated. (AIP)« less
  • A two-dimensional dynamical parameterized model is derived to study the M-(H{sub 2}) interaction in transition-metal molecular hydrogen complexes. The parameters have been adjusted to reproduce the observed inelastic neutron scattering transitions through a least-squares fit procedure. The vibrational levels are obtained by solving the nuclear Schroedinger equation in a discrete variable representation. From this procedure, structural information such as the barrier to rotation of the H{sub 2} ligand and the H-H distance have been obtained. The accuracy of the model is tested on four systems with M-(H{sub 2}) interactions of different nature. The resulting H-H bond distances are in verymore » good agreement with neutron diffraction structures where available.« less
  • We discuss the evolution of linear perturbations in a quintessence model in which the scalar field is nonminimally coupled to cold dark matter. We consider the effects of this coupling on both cosmic microwave background temperature anisotropies and matter perturbations. Because of the modification of the scale of cold dark matter as {rho}{sub c}={rho}{sub c}{sup (0)}a{sup -3+{xi}}, we can shift the turnover in the matter power spectrum even without changing the present energy densities of matter and radiation. This can be used to constrain the strength of the coupling. We find that the phenomenology of this model is consistent withmore » current observations up to the coupling power n{sub c}{<=}0.01 while adopting the current parameters measured by the Wilkinson Microwave Anisotropy Probe. Upcoming cosmic microwave background observations continuing to focus on resolving the higher peaks may put strong constraints on the strength of the coupling.« less
  • We evaluate the ability of future data sets to discriminate among different quintessence dark energy models. This approach gives an alternative (and complementary) measure for assessing the impact of future experiments, as compared with the large body of literature that compares experiments in abstract parameter spaces (such as the well-known w{sub 0}-w{sub a} parameters) and more recent work that evaluates the constraining power of experiments on individual parameter spaces of specific quintessence models. We use the Dark Energy Task Force (DETF) models of future data sets and compare the discriminative power of experiments designated by the DETF as stages 2,more » 3, and 4 (denoting increasing capabilities). Our work reveals a minimal increase in discriminating power when comparing stage 3 to stage 2, but a very striking increase in discriminating power when going to stage 4 (including the possibility of completely eliminating some quintessence models). We also see evidence that even modest improvements over DETF stage 4 (which many believe are realistic) could result in even more dramatic discriminating power among quintessence dark energy models. We develop and demonstrate the technique of using the independently measured modes of the equation of state (derived from principle component analysis) as a common parameter space in which to compare the different quintessence models, and we argue that this technique is a powerful one. We use the PNGB, Exponential, Albrecht-Skordis, and Inverse Tracker (or inverse power law) quintessence models for this work. One of our main results is that the goal of discriminating among these models sets a concrete measure on the capabilities of future dark energy experiments. Experiments have to be somewhat better than DETF stage 4 simulated experiments to fully meet this goal.« less
  • We evaluate the ability of future data sets to discriminate among different quintessence dark energy models. This approach gives an alternative (and complementary) measure for assessing the impact of future experiments, as compared with the large body of literature that compares experiments in abstract parameter spaces (such as the well-known w{sub 0}-w{sub a} parameters) and more recent work that evaluates the constraining power of experiments on individual parameter spaces of specific quintessence models. We use the Dark Energy Task Force (DETF) models of future data sets and compare the discriminative power of experiments designated by the DETF as stages 2,more » 3, and 4 (denoting increasing capabilities). Our work reveals a minimal increase in discriminating power when comparing stage 3 to stage 2, but a very striking increase in discriminating power when going to stage 4 (including the possibility of completely eliminating some quintessence models). We also see evidence that even modest improvements over DETF stage 4 (which many believe are realistic) could result in even more dramatic discriminating power among quintessence dark energy models. We develop and demonstrate the technique of using the independently measured modes of the equation of state (derived from principle component analysis) as a common parameter space in which to compare the different quintessence models, and we argue that this technique is a powerful one. We use the pseudo-Nambu-Goldstone boson, exponential, Albrecht-Skordis, and inverse tracker (or inverse power law) quintessence models for this work. One of our main results is that the goal of discriminating among these models sets a concrete measure on the capabilities of future dark energy experiments. Experiments have to be somewhat better than DETF stage 4 simulated experiments to fully meet this goal.« less