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A&A
Volume 485, Number 2, July II 2008
Page(s) L5 - L8
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200809974
Published online 22 May 2008


A&A 485, L5-L8 (2008)
DOI: 10.1051/0004-6361:200809974

Letter

A circumnuclear disk of atomic hydrogen in Centaurus A

R. Morganti1, 2, T. Oosterloo1, 2, C. Struve1, 2, and L. Saripalli3, 4

1  Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo, The Netherlands
    e-mail: morganti@astron.nl
2  Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
3  Raman Research Institute, CV Raman Avenue, Sadashivanagar, Bangalore 560080, India
4  CSIRO, Australia Telescope National Facility, PO Box 76, Epping NSW 1710, Australia

Received 15 April 2008 / Accepted 5 May 2008

Abstract
We present new observations, performed with the Australia Telescope Compact Array, of the $\ion{H}{i}$ absorption in the central regions of Centaurus A. For the first time, absorption is detected against the radio core at velocities blueshifted with respect to the systemic velocity. Moreover, the data show that the nuclear redshifted absorption component is broader than reported before. With these new results, the kinematics of the $\ion{H}{i}$ in the inner regions of Cen A appears very similar to that observed in emission for the molecular circumnuclear disk. This suggests that the central $\ion{H}{i}$ absorption is not, as was previously claimed, evidence of gas infall into the AGN, but instead is due to a cold, circumnuclear disk.


Key words: galaxies: active -- galaxies: ISM -- galaxies: individual: Centaurus A



© ESO 2008