Measuring Polarized Emission in Clusters in the CMB S4 Era

TL;DR

This paper explores the potential to detect polarized signals from galaxy clusters in future CMB S4 experiments, highlighting the challenges and the possibility of using the full catalog for detection.

Contribution

It demonstrates that while individual cluster signals are weak, the full catalog can enable detection, and the significance scales with the telescope mirror size.

Findings

Individual cluster polarization signal is about 0.5%.

Full catalog detection is feasible with increased significance.

Signal scales linearly with the telescope mirror size.

Abstract

The next generation of CMB experiments (CMB Stage-4) will produce a Sunyaev-Zel'dovich (SZ) cluster catalog containing $\sim10^{5}$ objects, two orders of magnitudes more than currently available. In this paper, we discuss the detectability of the polarized signal generated by scattering of the CMB quadrupole on the cluster electron gas using this catalog. We discuss the possibility of using this signal to measure the relationship between cluster optical depth and mass. We find that the area of observation of S4 maximizes the signal-to-noise (S/N) on the polarized signal but that this S/N is extremely small for an individual cluster, of order 0.5% for a typical cluster in our catalog, the main source of noise being the residual primordial E-mode signal. However, we find that the signal could be detected using the full cluster catalog and that the significance of the result will increase linearly with the size of the CMB S4 telescope mirror.