Constraining Perturbative Early Dark Energy with Current Observations

Abstract

In this work, we study a class of early dark energy (EDE) models, in which, unlike in standard DE models, a substantial amount of DE exists in the matter-dominated era, self-consistently including DE perturbations. Our analysis shows that, marginalizing over the non DE parameters such as $Omeg{a}_m,H_0,n_s$, current CMB observations alone can constrain the scale factor of transition from early DE to late time DE to $a_t\ge 0.44$ and width of transition to $Delt{a}_t\le 0.37$. The equation of state at present is somewhat weakly constrained to $w_0\le -0.6$, if we allow $H_0<60$ km/s/Mpc. Taken together with other observations, such as supernovae, HST, and SDSS LRGs, the constraints are tighter-- $w_0\le -0.9,a_t\le 0.19,{\Delta }_t\le 0.21$. The evolution of the equation of state for EDE models is thus close to $\Lambda$CDM at low redshifts. Incorrectly assuming DE perturbations to be negligible leads to different constraints on the equation of state parameters, thus highlighting the necessity of self-consistently including DE perturbations in the analysis. If we allow the spatial curvature to be a free parameter, then the constraints are relaxed to $w_0\le -0.77,a_t\le 0.35,{\Delta }_t\le 0.35$ with $-0.014<{\Omega }_{\kappa }<0.031$ for CMB+other observations. For perturbed EDE models, the $2\sigma$ lower limit on ${\sigma }_8$ (${\sigma }_8\ge 0.59$) is much lower than that in $\Lambda$CDM (${\sigma }_8\ge 0.72$), thus raising the interesting possibility of discriminating EDE from $\Lambda$CDM using future observations such as halo mass functions or the Sunyaev-Zeldovich power spectrum.

12 pages, 5 figures, references updated, accepted for publication in ApJ

References in corpus (17)

• Dynamics of dark energy
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Dark Energy and the Accelerating Universe
• New Hubble Space Telescope Discoveries of Type Ia Supernovae at z > 1: Narrowing Constraints on the Early Behavior of Dark Energy
• Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
• Observational Constraints on the Nature of the Dark Energy: First Cosmological Results from the ESSENCE Supernova Survey
• Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves
• A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder
• Reconstructing Dark Energy
• Cosmological Constraints from the Clustering of the Sloan Digital Sky Survey DR7 Luminous Red Galaxies
• High resolution CMB power spectrum from the complete ACBAR data set
• First-year Sloan Digital Sky Survey-II (SDSS-II) supernova results: consistency and constraints with other intermediate-redshift datasets
• Constraining Dark Energy Anisotropic Stress
• Voids of dark energy
• Roles of dark energy perturbations in the dynamical dark energy models: Can we ignore them?
• A comparison of perturbations in fluid and scalar field models of dark energy
• Evolution of scalar perturbations in cosmology with quintessential dark energy

Cited by in corpus (9)

• Measurement of Baryon Acoustic Oscillations in the Lyman-alpha Forest Fluctuations in BOSS Data Release 9
• Structure formation in inhomogeneous Early Dark Energy models
• Large-Scale Structure Formation with Massive Neutrinos and Dynamical Dark Energy
• Are $H_0$ and ${\sigma }_8$ tensions generic to present cosmological data?
• Redshift-space distortions in massive neutrino and evolving dark energy cosmologies
• Early dark energy and its interaction with dark matter
• Galaxy Clusters as a probe of early dark energy
• Freezing Out Early Dark Energy
• An Exploration of Heterogeneity in Supernova Type Ia Samples