Scalar field dark energy perturbations and the Integrated Sachs Wolfe effect

TL;DR

This paper examines how scalar field dark energy perturbations influence the Integrated Sachs Wolfe effect across different models, revealing that accounting for perturbations reduces differences between models and the cosmological constant.

Contribution

It provides a comparative analysis of the ISW effect in thawing and freezing scalar field dark energy models, emphasizing the importance of perturbations in model distinctions.

Findings

Perturbations make different dark energy models' ISW contributions more similar.

Ignoring perturbations overestimates differences between models.

Significant differences remain in the angular power spectrum contributions.

Abstract

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.