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Evolution of magnetic fields at high redshift
Author(s) -
Zweibel E.G.
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.200610573
Subject(s) - physics , magnetorotational instability , magnetic field , galaxy , redshift , astrophysics , accretion (finance) , intergalactic travel , cosmology , instability , plasma , magnetic reconnection , turbulence , magnetohydrodynamics , mechanics , quantum mechanics
The origin of magnetic fields in the Universe is a cosmology problem. The evolution of the field is a plasma physics problem. I review these problems and focus on magnetogenesis in accretion disks, specifically, the transition from the Biermann battery, which creates seed fields, to amplification by turbulence driven by magnetorotational instability. In collisional disks, there is a gap between the fieldstrength characteristic of the battery and the fieldstrength necessary to sustain magnetorotational instability, but in collisionless disks the transition occurs at low fieldstrength. Because collisionless disks are generally hot, and have short dynamical times, they are likely to be small. Thus, in the battery scenario, magnetic fields on large scales were built from fields created in many small sources. Simple estimates based on turbulent diffusion suggest that galaxies and the cores of galaxy clusters can be magnetized in this way, but not the intergalactic medium at large. The problem of creating a large‐scale field remains unsolved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)