EXTREME STARBURST OR CENTRAL ACTIVITY IN X-RAY LUMINOUS IRAS GALAXIES

ROSAT All Sky Survey observations of IRAS galaxies have revealed up to now a number of 10 optically non-Seyfert galaxies with X-ray (0.1-2.4) luminosities up to a few 10(43)erg.s(-1) (Boiler et al. 1992). The sources are brighter than previous detection limits of a few 10(41)erg.s(-1) as found by Stocke et al. (1991) or Green, Anderson and Ward (1992) for Einstein sources. The optical classification is based on follow-up observations which indicate clearly the non-Seyfert (LINER and HII region-like galaxies) nature. Our investigations reveal that galaxies classified as non-Seyferts on the basis of optical spectroscopy may reach exceptionally high X-ray luminosities which are similar to that of Seyfert galaxies. On the basis of the present observational material we suppose a hidden low luminosity AGN in the centre of these objects as the source of energy production. The objects are of interest when evaluating starburst versus central activity.