Constraining dark energy with the integrated Sachs-Wolfe effect

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.