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Issue A&A
Volume 370, Number 2, May I 2001
Page(s) 635 - 648
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20010267



A&A 370, 635-648 (2001)
DOI: 10.1051/0004-6361:20010267

The effects of vertical outflows on disk dynamos

A. Bardou1, B. von Rekowski1, W. Dobler1, A. Brandenburg1, 2 and A. Shukurov1

1  Department of Mathematics, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK
2  Nordita, Blegdamsvej 17, 2100 Copenhagen, Denmark

(Received 23 November 2000 / Accepted 15 February 2001)

Abstract
We consider the effect of vertical outflows on the mean-field dynamo in a thin disk. These outflows could be due to winds or magnetic buoyancy. We analyse both two-dimensional finite-difference numerical solutions of the axisymmetric dynamo equations and a free-decay mode expansion using the thin-disk approximation. Contrary to expectations, a vertical velocity can enhance dynamo action, provided the velocity is not too strong. In the nonlinear regime this can lead to super-exponential growth of the magnetic field.


Key words: accretion, accretion disks -- magnetic fields -- galaxies: magnetic fields

Offprint request: A. Bardou, Anne.Bardou@ncl.ac.uk




© ESO 2001


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