Publications of the Astronomical Society of Australia Publications of the Astronomical Society of Australia Society
Publications of the Astronomical Society of Australia
RESEARCH ARTICLE

Resolving the Nucleus of Centaurus A at Mid-Infrared Wavelengths

Leonard Burtscher A B E , Klaus Meisenheimer A , Walter Jaffe C , Konrad R. W. Tristram D and Huub J. A. Röttgering C

A Max Planck Institute for Astronomy, Heidelberg, Germany

B Fellow of the International Max Planck Research School (IMPRS) for Astronomy and Cosmic Physics, Heidelberg, Germany

C Max Planck Institute for Radio Astronomy, Bonn, Germany

D Sterrewacht Leiden, Leiden University, Leiden, The Netherlands

E Corresponding author. Email: burtscher@mpia.de

Publications of the Astronomical Society of Australia 27(4) 490-495 http://dx.doi.org/10.1071/AS09068
Submitted: 3 10 2009  Accepted: 4 8 2010   Published: 13 October 2010

Abstract

We have observed Centaurus A with the Mid-Infrared Interferometric Instrument (MIDI) at the Very Large Telescope Interferometer at resolutions of 7–15 mas (at 12.5 μm) and filled gaps in the (u,v) coverage in comparison to earlier measurements. We are now able to describe the nuclear emission in terms of geometric components and derive their parameters by fitting models to the interferometric data. With simple geometrical models, the best fit is achieved for an elongated disk with flat intensity profile with diameter 76 ± 9 × 35 ± 2 mas (1.41 ± 0.17 × 0.65 ± 0.03 pc) whose major axis is oriented at a position angle (PA) of 10.1 ± 2.2° east of north. A point source contributes 47 ± 11% of the nuclear emission at 12.5 μm. There is also evidence that neither such a uniform nor a Gaussian disk are good fits to the data. This indicates that we are resolving more complicated small-scale structure in active galactic nuclei with MIDI, as has been seen in Seyfert galaxies previously observed with MIDI. The PA and inferred inclination i = 62.6–2.6 +2.1° of the dust emission are compared with observations of gas and dust at larger scales.

Keywords: techniques: high angular resolution — galaxies: active


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