Magnetic helicity in galactic dynamos
arXiv:astro-ph/0204450
Abstract
Magnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, especially the constraints imposed by magnetic helicity conservation. We estimate the minimal strength of the large-scale magnetic field which could arise inspite of the helicity constraint.
7 pages, Invited talk at the 21st meeting of the Astronomical Society of India, Feb 5 - 8, IUCAA, Pune. To be published in the Bulletin of the Astronomical Society of India