Constraining dark energy with the integrated Sachs-Wolfe effect

TL;DR

This paper uses the integrated Sachs-Wolfe effect to significantly tighten constraints on dynamical dark energy models, reducing viable parameter space by about 70% and supporting the consistency with the standard Lambda Cold Dark Matter model.

Contribution

It introduces a method to incorporate ISW constraints from galaxy-CMB cross-correlations into dark energy model analysis, enhancing existing large-scale structure constraints.

Findings

ISW effect detection at ~5σ within ΛCDM.

Constraints consistent with ΛCDM, reducing parameter space by ~70%.

Effective field theory framework applied to dark energy models.

Abstract

We use the integrated Sachs-Wolfe (ISW) effect, by now detectable at $\sim 5\sigma$ within the context of $\Lambda{}$CDM cosmologies, to place strong constraints on dynamical dark energy theories. Working within an effective field theory framework for dark energy we find that including ISW constraints from galaxy-CMB cross-correlations significantly strengthens existing large-scale structure constraints, yielding bounds consistent with $\Lambda{}$CDM and approximately reducing the viable parameter space by $\sim 70\%$. This is a direct consequence of ${\cal O}(1)$ changes induced in these cross-correlations by otherwise viable dark energy models, which we discuss in detail. We compute constraints by adapting the $\Lambda{}$CDM ISW likelihood from [1] for dynamical dark energy models using galaxy data from 2MASS, WISE $\times$ SuperCOSMOS, SDSS-DR12, QSOs and NVSS, CMB data from Planck 18, and BAO and RSD large scale structure measurements from BOSS and 6dF. We show constraints both in terms of EFT-inspired $\alpha_i$ and phenomenological $\mu/\Sigma$ parametrisations. Furthermore we discuss the approximations involved and related aspects of bias modelling in detail and highlight what these constraints imply for the underlying dark energy theories.