Measuring the cosmological density field twice: A novel test of dark energy using the CMB quadrupole

TL;DR

This paper proposes a novel method to test dark energy by comparing reconstructed primordial CMB quadrupoles from galaxy cluster polarization signals with direct satellite measurements, potentially surpassing cosmic variance limits.

Contribution

It introduces a new approach using remote quadrupole measurements from galaxy clusters to test dark energy beyond traditional cosmic variance constraints.

Findings

Potential to test dark energy beyond cosmic variance

Method to reconstruct primordial fluctuations from cluster polarization

Comparison of local and satellite CMB quadrupoles

Abstract

The scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces polarization signals according to the quadrupole anisotropy in the photon distribution at the cluster location. This `remote quadrupole' derived from the measurements of the induced polarization provides an opportunity for reconstructing primordial fluctuations on large scales. We discuss that comparing the local CMB quadrupoles predicted by these reconstructed primordial fluctuations and the direct measurements done by CMB satellites may enable us to test the dark energy beyond cosmic variance limits.