Volume 548, December 2012
|Number of page(s)||11|
|Published online||26 November 2012|
Shearing box simulations of accretion disk winds⋆
Max-Planck-Institut für Astrophysik,
2 Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA
Received: 11 October 2011
Accepted: 10 October 2012
The launching process of a magnetically driven outflow from an accretion disk is investigated in a local shearing box model, which allows a study of the feedback between accretion and angular momentum loss. The mass-flux instability found in previous linear analyses of this problem is recovered in a series of 2D (axisymmetric) simulations in the MRI-stable (high magnetic field strength) regime. At low field strengths that are still sufficient to suppress MRI, the instability develops on a short radial length scale and saturates at a modest amplitude. At high field strengths, a long-wavelength “clump” instability of large amplitude and growth times of a few orbits is observed. As previously speculated, the unstable connection between disk and outflow may be relevant for the time dependence observed in jet-producing disks. The success of the simulations is due in large part to the implementation of an effective wave-transmitting upper boundary condition.
Key words: magnetohydrodynamics (MHD) / accretion, accretion disks / instabilities
Five movies are available in electronic form at http://www.aanda.org
© ESO, 2012
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