|Description:|| Centaurus A is the closest radio galaxy and is therefore the ideal target to study it on all scales: from the mega-parsec scale of the giant radio lobes down to the parsec scale of the vicinity of the active galactic nuclei (AGN).|
We have performed neutral hydrogen (HI) observations with the ATCA. The above picture shows an optical image (DSS) of Centaurus A. The HI in emission is plotted on top (blue) and follows nicely the warped dust lane out to a radius of 7kpc. Absorption (red) is detected against the southern radio lobe (not plotted) and against the nucleus.
Surprisingly, the absorption against the unresolved nucleus is red- and blueshifted w.r.t. the systemic velocity of the galaxy. Previously, only part of the redshifted absorption was known and interpreted as gas clouds close to the nucleus and probably falling in, potentially supplying the fuel that is needed for the AGN. Now, we are investigating whether the absorption could be explained by a circumnuclear rotating disk only - perhaps changing the interpretation of the fueling mechanism in Centaurus A....