Observational effects of the early episodically dominating dark energy
  We investigate observational consequences of the early episodically
dominating dark energy on the evolution of cosmological structures. For this
aim, we introduce the minimally coupled scalar field dark energy model with the
Albrecht-Skordis potential which allows a sudden ephemeral domination of dark
energy component during the radiation or early matter era. The conventional
cosmological parameters in the presence of such an early dark energy are
constrained with WMAP and Planck cosmic microwave background radiation data
including other external data sets. It is shown that in the presence of such an
early dark energy the estimated cosmological parameters can deviate
substantially from the currently known $\Lambda\textrm{CDM}$-based parameters,
with best-fit values differing by several percents for WMAP and by a percent
level for Planck data. For the latter case, only a limited amount of dark
energy with episodic nature is allowed since the Planck data strongly favors
the $\Lambda\textrm{CDM}$ model. Compared with the conventional dark energy
model, the early dark energy dominating near radiation-matter equality or at
the early matter era results in the shorter cosmic age or the presence of
tensor-type perturbation, respectively. Our analysis demonstrates that the
alternative cosmological parameter estimation is allowed based on the same
observations even in Einstein's gravity.
