Seyfert Activity and Nuclear Star Formation in the Circinus Galaxy

We present high angular resolution (0".15-0".5) near infrared images andspectroscopy of the Circinus galaxy, the closest Seyfert 2 galaxy known. Thedata reveal a non-stellar nuclear source at 2.2 microns. The coronal lineregion and the hot molecular gas emission extend for 20-50 pc in the ionizationcone. The data do not show evidence for a point-like concentration of darkmass; we set an upper limit of 4*10^6 Mo to the mass of a putative black hole. We find evidence for a young nuclear stellar population, with typical agesbetween 4*10^7 and 1.5*10^8 yrs. The luminosity of the starburst inside a fewhundred pc is comparable to the intrinsic luminosity of the Seyfert nucleus,and the two of them together account for most of the observed bolometricluminosity of the galaxy. Within the central 12 pc the starburst has an age ofabout 7*10^7 yrs and radiates about 2% of the luminosity of the active nucleus.We discuss the implications of these results for models that have been proposedfor the starburst-AGN connection.