Scalar field description of a parametric model of dark energy
  We investigate theoretical and observational aspects of a time-dependent
parameterization for the dark energy equation of state (EoS) $w(z)$, which is a
well behaved function of the redshift $z$ over the entire cosmological
evolution, i.e., $z \in [-1,\infty)$. By using a theoretical algorithm of
constructing the quintessence potential directly from the effective EoS
parameter, we derive and discuss the general features of the resulting
potential for this $w(z)$ function. Since the parameterization here discussed
allows us to divide the parametric plane in defined regions associated to
distinct classes of dark energy models, we use the most recent observations
from type Ia supernovae, baryon acoustic oscillation peak and Cosmic Microwave
Background shift parameter to check which class is observationally prefered. We
show that the largest portion of the confidence contours lies into the region
corresponding to a possible crossing of the so-called phanton divide line at
some point of the cosmic evolution.
