Cosmological bounds on oscillating dark energy models

We study the cosmological constraints on the two purely phenomenological models of oscillating dark energy. In these oscillating models, the equation of state of dark energy varies periodically. The periodic equation of state may provide the natural way to unify the early acceleration (inflation) and the late time acceleration of the Universe. These models give the effective way to tackle the cosmic coincidence problem. We examine the observational constraints on the oscillatory models from the latest observational data including the gold sample of 182 SNe type Ia, the shift parameter, R, given by the WMAP and the BAO measurements from the SDSS.