Parameter dependence of magnetized CMB observables

TL;DR

This paper investigates how pre-decoupling magnetic fields influence CMB temperature and polarization spectra, providing analytical and numerical methods to understand their parameter dependence for current observational constraints.

Contribution

It introduces a simplified analytical approach to compute magnetically-induced CMB distortions based on scaling properties, validated by numerical results.

Findings

Angular power spectra depend on magnetic field parameters through scaling integrals.

Analytical formulas accurately reproduce numerical results at small angular scales.

Magnetic field effects can be constrained using current CMB data.

Abstract

Pre-decoupling magnetic fields affect the scalar modes of the geometry and produce observable effects which can be constrained also through the use of current (as opposed to forthcoming) data stemming from the Cosmic Microwave Background observations. The dependence of the temperature and polarization angular power spectra upon the parameters of an ambient magnetic field is encoded in the scaling properties of a set of basic integrals whose derivation is simplified in the limit of small angular scales. The magnetically-induced distortions patterns of the relevant observables can be computed analytically by employing scaling considerations which are corroborated by numerical results.