Scalar field dark energy perturbations and the Integrated Sachs Wolfe
  effect
  Dark energy perturbation affects the growth of matter perturbations even in
scenarios with noninteracting dark energy. We investigate the Integrated Sachs
Wolfe (ISW) effect in various canonical scalar field models with perturbed dark
energy. We do this analysis for models belonging to the thawing and freezing
classes. We show that between these classes there is no clear difference for
the ISW effect. We show that on taking perturbations into account, the
contribution due to different models is closer to each other and to the
cosmological constant model as compared to the case of a smooth dark energy.
Therefore considering dark energy to be homogeneous gives an overestimate in
distinction between different models. However there are significant difference
between contribution to the angular power spectrum due to different models.
