Subramanian, Kandaswamy2012-03-132012-03-132002-07-06http://hdl.handle.net/11007/1398Magnetic 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 constraintenGalaxiesGalactic magnetic fields,Dynamos, magnetic helicityArticle