A parametric model for dark energy

Determining the mechanism behind the current cosmic acceleration constitutes a major question nowadays in theoretical physics. If the dark energy route is taken, this problem may potentially bring to light new insights not only in cosmology but also in high energy physics theories. Following this approach, we explore in this Letter some cosmological consequences of a new time-dependent parameterization for the dark energy equation of state (EoS), which is a well behaved function of the redshift z over the entire cosmological evolution, i.e., Z epsilon [-1, infinity). This parameterization allows us to divide the parametric plane (w(0), w(1)) in defined regions associated to distinct classes of dark energy models that can be confirmed or excluded from a confrontation with current observational data. By assuming a flat universe, a statistical analysis involving the most recent observations from type la supernovae, baryon acoustic oscillation peak, Cosmic Microwave Background shift parameter and Hubble evolution H(z) is performed to check the observational viability of the EoS parameterization here proposed. (C) 2008 Elsevier B.V. All rights reserved.