Systematic error due to isotropic inhomogeneities
  Usually the effects of isotropic inhomogeneities are not seriously taken into
account in the determination of the cosmological parameters because of
Copernican principle whose statement is that we do not live in the privileged
domain in the universe. But Copernican principle has not been observationally
confirmed yet in sufficient accuracy, and there is the possibility that there
are non-negligible large-scale isotropic inhomogeneities in our universe. In
this paper, we study the effects of the isotropic inhomogeneities on the
determination of the cosmological parameters and show the probability that
non-Copernican isotropic inhomogeneities mislead us into believing, for
example, the phantom energy of the equation of state, $p=w\rho$ with $w<-1$,
even in case that $w=-1$ is the true value.
