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Title: Quintessence reconstructed: New constraints and tracker viability

Abstract

We update and extend our previous work reconstructing the potential of a quintessence field from current observational data. We extend the cosmological data set to include new supernova data, plus information from the cosmic microwave background and from baryon acoustic oscillations. We extend the modeling by considering Pade approximant expansions as well as Taylor series, and by using observations to assess the viability of the tracker hypothesis. We find that parameter constraints have improved by a factor of 2, with a strengthening of the preference of the cosmological constant over evolving quintessence models. Present data show some signs, though inconclusive, of favoring tracker models over nontracker models under our assumptions.

Authors:
; ;  [1]
  1. Astronomy Centre, University of Sussex, Brighton BN1 9QH (United Kingdom)
Publication Date:
OSTI Identifier:
20935205
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.75.023502; (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; COSMIC RADIATION; COSMOLOGICAL CONSTANT; COSMOLOGICAL MODELS; COSMOLOGY; NONLUMINOUS MATTER; OSCILLATIONS; PADE APPROXIMATION; RADIOWAVE RADIATION; RELICT RADIATION; SERIES EXPANSION; SUPERNOVAE

Citation Formats

Sahlen, Martin, Liddle, Andrew R., and Parkinson, David. Quintessence reconstructed: New constraints and tracker viability. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.023502.
Sahlen, Martin, Liddle, Andrew R., & Parkinson, David. Quintessence reconstructed: New constraints and tracker viability. United States. doi:10.1103/PHYSREVD.75.023502.
Sahlen, Martin, Liddle, Andrew R., and Parkinson, David. Mon . "Quintessence reconstructed: New constraints and tracker viability". United States. doi:10.1103/PHYSREVD.75.023502.
@article{osti_20935205,
title = {Quintessence reconstructed: New constraints and tracker viability},
author = {Sahlen, Martin and Liddle, Andrew R. and Parkinson, David},
abstractNote = {We update and extend our previous work reconstructing the potential of a quintessence field from current observational data. We extend the cosmological data set to include new supernova data, plus information from the cosmic microwave background and from baryon acoustic oscillations. We extend the modeling by considering Pade approximant expansions as well as Taylor series, and by using observations to assess the viability of the tracker hypothesis. We find that parameter constraints have improved by a factor of 2, with a strengthening of the preference of the cosmological constant over evolving quintessence models. Present data show some signs, though inconclusive, of favoring tracker models over nontracker models under our assumptions.},
doi = {10.1103/PHYSREVD.75.023502},
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 confront tracker field quintessence with observational data. The potentials considered in this paper include V(φ)∝φ{sup −α}, exp (M{sub p}/φ), exp (M{sub p}/φ)−1, exp (βM{sub p}/φ) and exp (γM{sub p}/φ)−1; while the data come from the latest SN Ia, CMB and BAO observations. Stringent parameter constraints are obtained. In comparison with the cosmological constant via information criteria, it is found that models with potentials exp (M{sub p}/φ), exp (M{sub p}/φ)−1 and exp (γM{sub p}/φ)−1 are not supported by the current data.
  • We investigate the observational effects of a quintessence model in an anisotropic spacetime. The anisotropic metric is a non-rotating particular case of a generalized Gödel's metric and is classified as Bianchi III. This metric is an exact solution of the Einstein-Klein-Gordon field equations with an anisotropic scalar field ψ, which is responsible for the anisotropy of the spacetime geometry. We test the model against observations of type Ia supernovae, analyzing the SDSS dataset calibrated with the MLCS2k2 fitter, and the results are compared to standard quintessence models with Ratra-Peebles potentials. We obtain a good agreement with observations, with best valuesmore » for the matter and curvature density parameters Ω{sub M} = 0.29 and Ω{sub k}= 0.01 respectively. We conclude that present SNe Ia observations cannot, alone, distinguish a possible anisotropic axis in the cosmos.« less
  • We study quintessence and phantom field theory models based on linear-negative potentials of the form V({phi})=s{phi}. We investigate the predicted redshift dependence of the equation of state parameter w(z) for a wide range of slopes s in both quintessence and phantom models. We use the Gold data set of 157 SnIa and place constraints on the allowed range of slopes s. We find s=0{+-}1.6 for quintessence and s={+-}0.7{+-}1 for phantom models (the range is at the 2{sigma} level and the units of s are in {radical}(3)M{sub P}H{sub 0}{sup 2}{approx_equal}10{sup -38} eV{sup 3} where M{sub P} is the Planck mass). Inmore » both cases the best fit is very close to s{approx_equal}0 corresponding to a cosmological constant. We also show that specific model independent parametrizations of w(z) which allow crossing of the phantom divide line w=-1 (hereafter PDL) provide significantly better fits to the data. Unfortunately such crossings are not allowed in any phantom or quintessence single field model minimally coupled to gravity. Mixed models (coupled phantom-quintessence fields) can in principle lead to a w(z) crossing the PDL but a preliminary investigation indicates that this does not happen for natural initial conditions.« less
  • We determine the range of parameter space of an Interacting Quintessence Model that best fits the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. We only consider cosmological models with zero spatial curvature. We show that if the quintessence scalar field decays into cold dark matter at a rate that brings the ratio of matter to dark energy constant at late times, the cosmological parameters required to fit the CMB data are: dark energy density {omega}{sub x}=0.43{+-}0.12, baryon fraction {omega}{sub b}=0.08{+-}0.01, slope of the matter power spectrum at large scales n{sub s}=0.98{+-}0.02 and Hubble constant H{sub 0}=56{+-}4 km/s/Mpc. Themore » data prefers a dark energy component with a dimensionless decay rate parameter c{sup 2}=0.005 and noninteracting models are consistent with the data only at the 99.9% confidence level. Using the Bayesian Information Criteria we show that this extra parameter fits the data better than models with no interaction. The quintessence equation of state parameter is less constrained; i.e., the data sets an upper limit w{sub x}{<=}-0.86 at the same level of significance. When the WMAP anisotropy data are combined with supernovae data, the density parameter of dark energy increases to {omega}{sub x}{approx_equal}0.68 while c{sup 2} augments to 6.3x10{sup -3}. Models with quintessence decaying into dark matter provide a clean explanation for the coincidence problem and are a viable cosmological model, compatible with observations of the CMB, with testable predictions. Accurate measurements of baryon fraction and/or of matter density independent of the CMB data, would support/disprove these models.« less