Magnetic field amplification in CDM anisotropic collapse

Abstract

We use the Zel'dovich approximation to analyse the amplification of magnetic fields in gravitational collapse of cold dark matter during the mildly nonlinear regime, and identify two key features. First, the anisotropy of collapse effectively eliminates one of the magnetic components, confining the field in the pancake plane. Second, in agreement with recent numerical simulations, we find that the shear anisotropy can amplify the magnetic field well beyond the isotropic case. Our results suggest that the magnetic strengths observed in spiral and disk galaxies today might have originated from seeds considerably weaker than previous estimates.

small changes, including estimates in agreement with numerical results; version accepted by MNRAS

References in corpus (4)

• Magnetic Fields in the Early Universe
• Origin of Galactic and Extragalactic Magnetic Fields
• Magnetized cosmological perturbations
• Milestones in the Observations of Cosmic Magnetic Fields

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• Superadiabatic-type magnetic amplification in conventional cosmology
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