Ohmic currents and pre-decoupling magnetism

TL;DR

This paper investigates the role of Ohmic currents before decoupling in the early universe, analyzing their effects on curvature perturbations and how they depend on conductivity evolution.

Contribution

It provides a detailed analysis of Ohmic currents in a relativistic inhomogeneous background, highlighting their influence on cosmological perturbations.

Findings

Ohmic electric fields are balanced against Hall and thermoelectric effects.

Ohmic currents significantly impact the evolution of curvature perturbations.

The effect depends explicitly on the evolution of conductivity.

Abstract

Ohmic currents induced prior to decoupling are investigated in a standard transport model accounting both for the expansion of the background geometry as well as of its relativistic inhomogeneities. The relative balance of the Ohmic electric fields in comparison with the Hall and thermoelectric contributions is specifically addressed. The impact of the Ohmic currents on the evolution of curvature perturbations is discussed numerically and it is shown to depend explicitly upon the evolution of the conductivity.