The Magnetic Helicity Current in an Alpha-Omega Dynamo
Abstract
Conservation of magnetic helicity plays a critical role in suppressing mean-field dynamo action. Successful large scale dynamo action can occur if, and only if, the local turbulence is biased to drive a magnetic helicity current. In the case of a disk dynamo, the required magnetic helicity current is vertical and imposes a connection between the corona and the dynamo. The sign of the magnetic helicity current determines whether we get a dynamo or an anti-dynamo. The latter is more likely in systems in which angular momentum is driven outward by local turbulence. A successful galactic dynamo in an L* spiral disk will magnetize the surrounding intergalactic medium within several hundred kpc to ∼ 10-9 Gauss.
- Publication:
-
The Magnetized Plasma in Galaxy Evolution
- Pub Date:
- June 2005
- Bibcode:
- 2005mpge.conf..177V