Turbulence simulation of fratricide alpha-Omega dynamos
by
Alexander Hubbard(Nordita)
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Europe/Stockholm
122:026
122:026
Description
Helically forced magneto-hydrodynamic shearing-sheets can support different large-scale dynamo modes,
although the α-Ω mode is generally expected to dominate as it is the fastest growing.
In an α-Ω dynamo, most of the field amplification is produced by shear. Differential
rotation is a ubiquitous source of shear in astrophysics so astrophysical large-scale magnetic
fields are believed to usually be the result of such dynamos.
We present shearing-sheet simulations where the α-Ω mode
is instead replaced, after initial dominance and saturation,
by an orthogonal α mode, which is sustained by the helical
turbulence alone. We show that
there are at least two processes by which this transition can occur.