Fast growth of magnetic fields in galaxy clusters: A self-accelerating dynamo

A. A. Schekochihin, S. C. Cowley

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 108 over a cosmologically short time of ∼ 108 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field-amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small-scale fluctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ∼ 10-15 G to trigger the explosive growth).

Original languageEnglish (US)
Pages (from-to)599-604
Number of pages6
JournalAstronomische Nachrichten
Issue number5-6
StatePublished - 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies: clusters: general
  • Galaxies: magnetic fields
  • Intergalactic medium


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