Decay of Magnetic Fields in the Early Universe
Astrophysics
2017-08-23 v1 High Energy Physics - Phenomenology
Abstract
We study the evolution of a stochastic helical magnetic field generated in the early Universe after the electroweak phase transition, using standard magnetohydrodynamics (MHD). We find how the coherence length xi, magnetic energy E_M and magnetic helicity H evolve with time. We show that the self-similarity of the magnetic power spectrum alone implies that xi ~ t^{1/2}. This in turn implies that magnetic helicity decays as H ~ t^{-2s}, and that the magnetic energy decays as E_M ~ t^{-0.5-2s}, where s is inversely proportional to the magnetic Reynolds number Re_M. These laws improve on several previous estimates.
Cite
@article{arxiv.astro-ph/0302320,
title = {Decay of Magnetic Fields in the Early Universe},
author = {Mark Hindmarsh and M. Christensson and A. Brandenburg},
journal= {arXiv preprint arXiv:astro-ph/0302320},
year = {2017}
}
Comments
5pp LaTeX + World Sci procs class, 3 eps figs. Talk given at Strong and Electroweak Matter, Oct 2-5 2002, Heidelberg