The supernova-regulated ISM - II. The mean magnetic field

F. A. Gent*, A. Shukurov, G. R. Sarson, A. Fletcher, M. J. Mantere

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

70 Citations (Scopus)


The origin and structure of the magnetic fields in the interstellar medium of spiral galaxies is investigated with 3D, non-ideal, compressible magnetohydrodynamic simulations, including stratification in the galactic gravity field, differential rotation and radiative cooling. A rectangular domain, 1 x 1 x 2 kpc(3) in size, spans both sides of the galactic mid-plane. Supernova explosions drive transonic turbulence. A seed magnetic field grows exponentially to reach a statistically steady state within 1.6 Gyr. Following Germano (1992), we use volume averaging with a Gaussian kernel to separate magnetic field into a mean field and fluctuations. Such averaging does not satisfy all Reynolds rules, yet allows a formulation of mean-field theory. The mean field thus obtained varies in both space and time. Growth rates differ for the mean-field and fluctuating field and there is clear scale separation between the two elements, whose integral scales are about 0.7 and 0.3 kpc, respectively.

Original languageEnglish
Pages (from-to)L40-L44
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - Mar 2013
MoE publication typeA1 Journal article-refereed


  • dynamo
  • MHD
  • turbulence
  • ISM: kinematics and dynamics
  • galaxies: ISM


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