Unplugging the Universe: the neglected electromagnetic consequence of decoupling

TL;DR

This paper explores how magnetic flux decay during recombination can generate energetic electrons, potentially impacting cosmic evolution by delaying recombination, aiding early structure formation, and seeding reionization.

Contribution

It introduces an electromagnetic perspective on the recombination phase transition, highlighting the role of decaying magnetic fields in particle acceleration and cosmic evolution.

Findings

Energetic electrons produced during recombination could influence cosmic evolution.

Magnetic flux decay may delay the end of the recombination era.

Accelerated particles could serve as seeds for reionization at z ≈ 10.

Abstract

This letter concentrates on the non-equilibrium evolution of magnetic field structures at the onset of recombination, when the charged particle current densities decay as neutrals are formed. We consider the effect that a decaying magnetic flux has on the acceleration of particles via the transient induced electric field. Since the residual charged-particle number density is small as a result of decoupling, we shall consider the magnetic and electric fields essentially to be imposed, neglecting the feedback from any minority accelerated population. We find that the electromagnetic treatment of this phase transition can produce energetic electrons scattered throughout the Universe. Such particles could have a significant effect on cosmic evolution in several ways: (i) their presence could delay the effective end of the recombination era; (ii) they could give rise to plasma concentrations that could enhance early gravitational collapse of matter by opposing cosmic expansion to a greater degree than neutral matter could; (iii) they could continue to be accelerated, and become the seed for reionisation at the later epoch $z \approx 10$.