Properties and uncertainties of scalar field models of dark energy with
  barotropic equation of state
  The dynamics of expansion and large scale structure formation in the
multicomponent Universe with dark energy modeled by the minimally coupled
scalar field with generalized linear barotropic equation of state (EoS) are
analyzed. It is shown that the past dynamics of expansion and future of the
Universe -- eternal accelerated expansion or turnaround and collapse -- are
completely defined by the current energy density of a scalar field and relation
between its current and early EoS parameters. The clustering properties of such
models of dark energy and their imprints in the power spectrum of matter
density perturbations depend on the same relation and, additionally, on the
"effective sound speed" of a scalar field, defined by its Lagrangian. It is
concluded that such scalar fields with different values of these parameters are
distinguishable in principle. This gives the possibility to constrain them by
confronting the theoretical predictions with the corresponding observational
data. For that we have used the 7-year WMAP data on CMB anisotropies, the
Union2 dataset on Supernovae Ia and SDSS DR7 data on luminous red galaxies
(LRG) space distribution. Using the Markov Chain Monte Carlo technique the
marginalized posterior and mean likelihood distributions are computed for the
scalar fields with two different Lagrangians: Klein-Gordon and
Dirac-Born-Infeld ones. The properties of such scalar field models of dark
energy with best fitting parameters and uncertainties of their determination
are also analyzed in the paper.
