Magnetic fields in irregular galaxies

Some sort of a dynamo is possibly at work even in irregular galaxies with high star formation rate, like NGC4449. In spite of slow rotation and small size we discovered in this object large scale magnetic fields. This requires a fast acting dynamo. In the last decade some modifications of a classical dynamo were proposed based on additional instabilities of ISM and the reconnection mechanism.

NGC 4449 - contours of radio emission at 8.46 GHz (3.6 cm), magnetic field vectors and H-alpha image in colours. The magnetic fields in this irregular galaxy reaches 14microG, like in typical spiral galaxies! (Chyy et al. 2000).


But some small, irregular galaxies are below the efficiency level of the large-scale dynamo mechanism and posses magnetic fields on small scales only. Like in NGC 6822, below (Chyy et al. 2003).