The small-scale dynamo and the amplification of magnetic fields in massive primordial haloes

M. A. Latif, D. R.G. Schleicher, W. Schmidt, J. Niemeyer

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)

Abstract

While the present standard model of cosmology yields no clear prediction for the initial magnetic field strength, efficient dynamo action may compensate for initially weak seed fields via rapid amplification. In particular, the small-scale dynamo is expected to exponentially amplify any weak magnetic field in the presence of turbulence. We explore whether this scenario is viable using cosmological magneto-hydrodynamics simulations modelling the formation of the first galaxies, which are expected to form in so-called atomic cooling haloes with virial temperatures Tvir ≥ 104 K. As previous calculations have shown that a high Jeans resolution is needed to resolve turbulent structures and dynamo effects, our calculations employ resolutions of up to 128 cells per Jeans length. The presence of the dynamo can be clearly confirmed for resolutions of at least 64 cells per Jeans length, while saturation occurs at approximate equipartition with turbulent energy. As a result of the large Reynolds numbers in primordial galaxies, we expect saturation to occur at early stages, implying magnetic field strengths of ~0.1 μG at densities of 104 cm-3.

Original languageEnglish
Pages (from-to)668-678
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume432
Issue number1
DOIs
Publication statusPublished - Jun 2013
Externally publishedYes

Keywords

  • Cosmology: theory
  • Early universe
  • Galaxies: formation
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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