In this thesis we study some observational consequences of dark energy
dominated cosmologies. After reviewing the main characteristics of
quintessential models of dark energy, by using the SN Ia data and the position
of the CMB peaks we constrain a class of parameterized scalar field potentials.
Going beyond constraining specific classes models, we introduce a
parameterization of the dark energy equation of state. Such an approach allows
us to study in a model independent way the imprint dark energy leaves in the
CMB power spectrum. Finally we develop a formalism to model localized CMB
anisotropies and compute analytical formulae for the power spectrum and the
bispectrum.Comment: PhD thesis, University of Sussex, 109 page