Early Cosmological Evolution of Primordial Electromagnetic Fields

Abstract

It is usually assumed that when Weyl invariance is unbroken in the electromagnetic sector, the energy density of primordial magnetic fields will redshift as radiation. Here we show that primordial magnetic fields do not exhibit radiation-like redshifting in the presence of stronger electric fields, as a consequence of Faraday's law of induction. In particular for the standard Maxwell theory, magnetic fields on super-horizon scales can redshift as $B^2\propto a^{-6}{H}^{-2}$, instead of the usually assumed $a^{-4}$. Taking into account this effect for inflationary magnetogenesis can correct previous estimates of the magnetic field strength by up to 37 orders of magnitude. This opens new possibilities for inflationary magnetogenesis, and as an example we propose a scenario where femto-Gauss intergalactic magnetic fields are created on Mpc scales, with high-scale inflation producing observable primordial gravitational waves, and reheating happening at low temperatures.

26 pages, 2 figures; v2: published in PRD

References in corpus (9)

• Magnetic fields from inflation?
• Cosmology with inhomogeneous magnetic fields
• Adding helicity to inflationary magnetogenesis
• Schwinger Effect in 4D de Sitter Space and Constraints on Magnetogenesis in the Early Universe
• Universal upper limit on inflation energy scale from cosmic magnetic field
• Universal Constraints on Axions from Inflation
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• On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
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Cited by in corpus (8)

• Inflationary magnetogenesis with reheating phase from higher curvature coupling
• Schwinger Mechanism During Inflation
• Parker Bound and Monopole Pair Production from Primordial Magnetic Fields
• Primordial Magnetogenesis in a Bouncing Universe
• Simulating relic gravitational waves from inflationary magnetogenesis
• Astrophysics in Strong Electromagnetic Fields and Laboratory Astrophysics
• Impact of Helical Electromagnetic Fields on the Axion Window
• Electromagnetic conversion into kinetic and thermal energies