Generalized CMB initial conditions with pre-equality magnetic fields

TL;DR

This paper derives the most general initial conditions for CMB anisotropies considering pre-equality magnetic fields, analyzing their effects on angular power spectra and potential degeneracies.

Contribution

It introduces a comprehensive set of magnetized initial conditions for the Einstein-Boltzmann hierarchy and explores their observational implications.

Findings

Analytical solutions for magnetized initial modes

Numerical integration of the Einstein-Boltzmann hierarchy

Discussion of degeneracies in initial conditions at high multipoles

Abstract

The most general initial conditions of CMB anisotropies, compatible with the presence of pre-equality magnetic fields, are derived. When the plasma is composed by photons, baryons, electrons, CDM particles and neutrinos, the initial data of the truncated Einstein-Boltzmann hierarchy contemplate one magnetized adiabatic mode and four (magnetized) non-adiabatic modes. After obtaining the analytical form of the various solutions, the Einstein-Boltzmann hierarchy is numerically integrated for the corresponding sets of initial data. The TT, TE and EE angular power spectra are illustrated and discussed for the magnetized generalization of the CDM-radiation mode, of the baryon-radiation mode and of the non-adiabatic mode of the neutrino sector. Mixtures of initial conditions are examined by requiring that the magnetized adiabatic mode dominates over the remaining non-adiabatic contributions. In the latter case, possible degeneracies between complementary sets of initial data might be avoided through the combined analysis of the TT, TE and EE angular power spectra at high multipoles (i.e. $\ell >1000$).