Remarks on Dynamical Dark Energy Measured by the Conformal Age of the Universe

Abstract

We elaborate on a model of conformal dark energy (dynamical dark energy measured by the conformal age of the universe) recently proposed in [H. Wei and R.G. Cai, arXiv:0708.0884] where the present-day dark energy density was taken to be ${\rho }_q\equiv 3{\alpha }^2{m}_P^2/{\eta }^2$, where $\eta$ is the conformal time and $\alpha$ is a numerical constant. In the absence of an interaction between the ordinary matter and dark energy field $q$, the model may be adjusted to the present values of the dark energy density fraction $\Omega \mathbb{Z}q\simeq 0.73$ and the equation of state parameter $w\mathbb{Z}q<-0.78$, if the numerical constant $\alpha$ takes a reasonably large value, $\alpha \gtrsim 2.6$. However, in the presence of a nontrivial gravitational coupling of $q$-field to matter, say $\tilde{Q}$, the model may be adjusted to the values $\Omega \mathbb{Z}q\simeq 0.73$ and $w\mathbb{Z}q\simeq -1$, even if $\alpha \sim \mathcal{O}(1)$, given that the present value of $\tilde{Q}$ is large. Unlike for the model in [R.G. Cai, arXiv:0707.4049], the bound $\Omega \mathbb{Z}q<0.1$ during big bang nucleosynthesis (BBN) may be satisfied for almost any value of $\alpha$. Here we discuss some other limitations of this proposal as a viable dark energy model. The model draws some parallels with the holographic dark energy; we also briefly comment on the latter model.

16 pages, 10 figures, a reference added, the version to appear in Phys. Rev. D

References in corpus (11)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Dynamics of dark energy
• Reconstructing Dark Energy
• A Dark Energy Model Characterized by the Age of the Universe
• A New Model of Agegraphic Dark Energy
• Cosmological Constraints on New Agegraphic Dark Energy
• Instability of agegraphic dark energy models
• Gauss-Bonnet cosmologies: crossing the phantom divide and the transition from matter dominance to dark energy
• Cosmological implications of Karolyhazy uncertainty relation
• Towards Inflation and Accelerating Cosmologies in String-Generated Gravity Models
• Observational Constraints on Agegraphic Dark Energy

Cited by in corpus (10)

• A Holographic Dark Energy Model from Ricci Scalar Curvature
• Holographic dark energy models: A comparison from the latest observational data
• Holographic Ricci dark energy: Current observational constraints, quintom feature, and the reconstruction of scalar-field dark energy
• Interacting Agegraphic Dark Energy
• Quintessence reconstruction of the new agegraphic dark energy model
• Entropy-Corrected Holographic Dark Energy
• New agegraphic dark energy model with generalized uncertainty principle
• Holographic Ricci dark energy in Randall-Sundrum braneworld: Avoidance of big rip and steady state future
• Agegraphic dark energy: growth index and cosmological implications
• Spherical collapse model in agegraphic dark energy cosmologies