Primordial Magnetism in CMB B-modes

TL;DR

This paper reviews how Faraday Rotation of CMB polarization can serve as a distinctive signature of primordial magnetic fields, highlighting its frequency dependence and potential for upcoming experiments.

Contribution

It provides a comprehensive review of Faraday Rotation signatures in CMB polarization and discusses expected constraints on primordial magnetic fields from future observations.

Findings

FR induces characteristic frequency-dependent B-modes

Mode-coupling correlations help distinguish magnetic fields

Upcoming CMB experiments can effectively probe primordial magnetism

Abstract

Cosmic Microwave Background (CMB) polarization B-modes induced by Faraday Rotation (FR) can provide a distinctive signature of primordial magnetic fields because of their characteristic frequency dependence and because they are only weakly damped on small scales. FR also leads to mode-coupling correlations between the E and B type polarization, and between the temperature and the B-mode. These additional correlations can further help distinguish magnetic fields from other sources of B-modes. We review the FR induced CMB signatures and present the constraints on primordial magnetism that can be expected from upcoming CMB experiments. Our results suggest that FR of CMB will be a promising probe of primordial magnetic fields.