Star formation in southern Seyfert galaxies

We have produced radio maps, using the Australia Telescope Compact Array, of the central regions of six southern type 2 Seyfert galaxies (NGC 1365, 4945, 6221, 6810, 7582 and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN). The radio morphologies range from extended diffuse structures to compact nuclear emission, with no evidence, even in the relatively compact sources, for synchrotron self-absorption. In each case the radio to far-infrared (FIR) ratio has a value consistent with star formation, and in all but one case the radio to [Fe rr] ratio is also consistent with star formation. We derive supernova rates and conclude that, despite the presence of a Seyfert nucleus in these galaxies, the radio, FIR and [Fe II] line emissions are dominated by processes associated with the circumnuclear star formation (i.e. supernova remnants and H rr regions) rather than with the AGN.