The Discovery of Optical Emission Knots in the Inner Jet of Centaurus A

Abstract

Jets have been the subject of increasing optical study in recent years. Because of better instrumental sensitivity, relatively high resolution spectra can now be obtained which are enormously helpful probes of the underlying physical processes, especially when combined with information from other wavelengths. With this in mind we attempted to discover optical counterparts to the X-ray (Feigelson et al. 1981) and radio (Schreier et al. 1981, Burns et. al. 1982) knots recently discovered in the inner jet region of Centaurus A. The coincident X-ray and radio knots lie in the same direction as previously studied optical features in the outer jet (Blanco et. al. 1975; Dufour and van den Bergh 1978, Osmer 1978; Graham and Price, 1981) but the latter are between 4 and 40 times further from the nucleus. Our study concentrated on the inner region, 2 kpc from the nucleus, where dust obscuration and the high level of background brightness discourage optical identification.