Centaurus A: Molecular gas shells or large-scale outflow?

Abstract

In order to test if the molecular \shells observed by Charmandaris et al. (2000) could be due to a molecular outflow, we have mapped CO inJ =1 ! 0a nd 2! 1 along the jet axis of Centaurus A. Where our map coincides with their observed positions, like them, we obtain 4 detections with a similar antenna temperature for CO 1 ! 0, although both transitions appear to be somewhat wider in velocity dispersion than theirs. As well as these, we have several tentative detections at distances of >5 kpc from the nucleus, and although these results are of too poor quality in order to verify or refute the shell model in favour of a molecular outflow, our observations of the inner kpc do suggest that at least a small-scale outflow is a possibility. Whether this would be a component of a larger-scale outflow or exists in conjunction with the molecular gas shells will have to wait for a much more extensive mapping of the large-scale gas distribution in Centaurus A, for which these and the results of Charmandaris et al. (2000) will hopefully provide sucient motivation.