Constraining the topology of the Universe using the polarised CMB maps

TL;DR

This paper explores using polarised CMB maps to constrain the universe's topology, demonstrating advantages over temperature data and assessing detectability thresholds with current and future experiments.

Contribution

It introduces a novel method applying the matched circles statistic to polarised CMB maps and evaluates its effectiveness for detecting universe topologies.

Findings

Polarised CMB maps improve topology detection sensitivity.

Next-generation experiments can detect smaller matched circles.

Reionisation-generated polarisation does not hinder detection.

Abstract

We study the possibility for constraining the topology of the Universe by means of the matched circles statistic applied to polarised cosmic microwave background (CMB) anisotropy maps. The advantages of using the CMB polarisation maps in studies of the topology over simply analysing the temperature data as has been done to-date are clearly demonstrated. We test our algorithm to search for pairs of matched circles on simulated CMB maps for a universe with the topology of 3-torus. It is found that the noise levels of both Planck and next generation CMB experiments data are no longer prohibitive and should be low enough to enable the use of the polarisation maps for such studies. For such experiments the minimum radius of the back-to-back matched circles which can be detected are determined. We also showed that the polarisation generated after reionisation does not have an impact on detectability of the matched circles.