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Amplification of magnetic fields by supernova‐driven turbulence
Author(s) -
Kim J.,
Balsara D. S.
Publication year - 2006
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200610551
Subject(s) - physics , dynamo , supernova , astrophysics , magnetic field , galaxy , ejecta , stars , dynamo theory , turbulence , astronomy , mechanics , quantum mechanics
Observations of μG magnetic fields in radio galaxies at cosmological epochs as early as around z = 2 have shortened the available time for dynamo action. This fact suggests that the mean‐field dynamo mechanism in a global galactic scale either is too slow to amplify a seed field generated by the Biermann battery effect to the level of the observed field strength at z ∼ 2 or needs much stronger seed fields of an order of 10 –10 G. A “contamination” picture that amplified magnetic fields in smaller objects, such as stars or AGNs, within a relatively shorter timescale spread out through supernova ejecta, stellar winds, and AGN jets to nearby environments is gaining momentum. In line with this picture, we demonstrate, through three‐dimensional numerical experiments, that magnetic fields can be amplified by supernova‐driven turbulence with two orders of magnitude smaller e‐folding timescale than that of the mean‐field dynamo mechanism. Therefore, supernova‐driven turbulence may play an important role in amplifying small‐scale B ‐fields in any astrophysical systems that have harbored massive stars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)