AbstractWe consider a late closed universe of which
scale factor is a power function of time using observational
data from combined WMAP5+BAO+SN Ia dataset and
WMAP5 dataset. The WMAP5 data give power-law exponent,α=1.01 agreeing with the previous study ofH(z)
data while combined data givesα=0.985. Considering a
scalar field dark energy and dust fluid evolving in the powerlaw universe, we find field potential, field solution and equation of state parameters. Decaying from dark matter into
dark energy is allowed in addition to the non-interaction
case. Time scale characterizing domination of the kinematic expansion terms over the dust and curvature terms
in the scalar field potential are found to be approximately
5.3 to 5.5 Gyr. The interaction affects in slightly lowering
the height of scalar potential and slightly shifting potential
curves rightwards to later time. Mass potential function of
the interacting Lagrangian term is found to be exponentially
decay function.