Is it possible to observationally distinguish adiabatic Quartessence from LambdaCDM?

Abstract

The equation of state (EOS) in quartessence models interpolates between two stages: $p\simeq 0$ at high energy densities and $p\approx -\rho$ at small ones. In the quartessence models analyzed up to now, the EOS is convex, implying increasing adiabatic sound speed ($c_s^2$) as the energy density decreases in an expanding Universe. A non-negligible $c_s^2$ at recent times is the source of the matter power spectrum problem that plagued all convex (non-silent) quartessence models. Viability for these cosmologies is only possible in the limit of almost perfect mimicry to $\Lambda$CDM. In this work we investigate if similarity to $\Lambda$CDM is also required in the class of quartessence models whose EOS changes concavity as the Universe evolves. We focus our analysis in the simple case in which the EOS has a step-like shape, such that at very early times $p\simeq 0$, and at late times $p\simeq const<0$. For this class of models a non-negligible $c_s^2$ is a transient phenomenon, and could be relevant only at a more early epoch. We show that agreement with a large set of cosmological data requires that the transition between these two asymptotic states would have occurred at high redshift ($z_t\gtrsim 38$). This leads us to conjecture that the cosmic expansion history of any successful non-silent quartessence is (practically) identical to the $\Lambda$CDM one.

5 pages, 7 figures, revised version to appear in PRD

References in corpus (25)

• Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
• Cosmological parameters from SDSS and WMAP
• An alternative to quintessence
• Generalized Chaplygin Gas, Accelerated Expansion and Dark Energy-Matter Unification
• The 3D power spectrum of galaxies from the SDSS
• Unification of Dark Matter and Dark Energy: the Inhomogeneous Chaplygin Gas
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Angular Power Spectrum
• Constraints on dark energy from Chandra observations of the largest relaxed galaxy clusters
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Parameter Estimation Methodology
• The end of unified dark matter?
• WMAP and the Generalized Chaplygin Gas
• Constraints on the generalized Chaplygin gas from supernovae observations
• The Revival of the Unified Dark Energy-Dark Matter Model ?
• The Power Spectrum of Mass Fluctuations Measured from the Lyman-alpha Forest at Redshift z=2.5
• Generalized Chaplygin gas as a unified scenario of dark matter/energy: observational constraints
• Cosmological Effects of a Class of Fluid Dark Energy Models
• Matter Power Spectrum from the Lyman-Alpha Forest: Myth or Reality?
• Constraints on Chaplygin quartessence from the CLASS gravitational lens statistics and supernova data
• Supernovae constraints on models of dark energy revisited
• Entropy perturbations in quartessence Chaplygin models
• Observational Constraints on Chaplygin Quartessence: Background Results
• Challenges for Kinetic Unified Dark Matter
• Bayesian Analysis of the (Generalized) Chaplygin Gas and Cosmological Constant Models using the 157 gold SNe Ia Data
• Observational Constraints on Silent Quartessence
• Matter Power Spectrum for Convex Quartessence

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