Cosmic polarimetry in magnetoactive plasmas

TL;DR

This paper investigates how large-scale cosmic magnetic fields influence the polarization of the CMB, providing analytical and numerical predictions of B-mode spectra and new constraints on primordial magnetism.

Contribution

It offers the first combined analysis of B-mode polarization data within a magnetized $ ext{Λ}$CDM framework and derives novel constraints on pre-equality cosmic magnetism.

Findings

Computed B-mode polarization spectra analytically and numerically.

Performed combined analysis of all available B-mode data.

Established new limits on primordial magnetic fields before equality.

Abstract

Polarimetry of the Cosmic Microwave Background (CMB) represents one of the possible diagnostics aimed at testing large-scale magnetism at the epoch of the photon decoupling. The propagation of electromagnetic disturbances in a magnetized plasma leads naturally to a B-mode polarization whose angular power spectrum is hereby computed both analytically and numerically. Combined analyses of all the publicly available data on the B-mode polarization are presented, for the first time, in the light of the magnetized $\Lambda$CDM scenario. Novel constraints on pre-equality magnetism are also derived in view of the current and expected sensitivities to the B-mode polarization.