Galaxy Clusters as a probe of early dark energy

TL;DR

This paper investigates early dark energy models with significant dark energy presence during matter domination, demonstrating how galaxy cluster observations can effectively constrain these models and distinguish them from standard LCDM.

Contribution

It introduces a self-consistent inclusion of dark energy perturbations in EDE models and shows how future galaxy cluster data can constrain EDE parameters.

Findings

Galaxy clusters' mass function constrains EDE equation of state.

SZ power spectrum helps determine EDE transition redshift.

Future surveys provide competitive constraints on EDE parameters.

Abstract

We study a class of early dark energy (EDE) models, in which, unlike in standard dark energy models, a substantial amount of dark energy exists in the matter-dominated era. We self-consistently include dark energy perturbations, and show that these models may be successfully constrained using future observations of galaxy clusters, in particular the redshift abundance, and the Sunyaev-Zel'dovich (SZ) power spectrum. We make predictions for EDE models, as well as LCDM for incoming X-ray (eROSITA) and microwave (South Pole Telescope) observations. We show that galaxy clusters' mass function and the SZ power spectrum will put strong constraints both on the equation of state of \de today and the redshift at which EDE transits to present-day LCDM like behavior for these models, thus providing complementary information to the geometric probes of dark energy. Not including perturbations in EDE models leads to those models being practically indistinguishable from LCDM. An MCMC analysis of future galaxy cluster surveys provides constraints for EDE parameters that are competitive with and complementary to background expansion observations such as supernovae.