Journal Article

Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: revealing the inner funnel of dust

David Raban, Walter Jaffe, Huub Röttgering, Klaus Meisenheimer and Konrad R. W. Tristram

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 3, pages 1325-1337
Published in print April 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI:
Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: revealing the inner funnel of dust

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We present new interferometric data obtained with mid-infrared interferometric instrument (MIDI) for the type II Seyfert galaxy NGC 1068, with an extensive coverage of 16 uv points. These observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, sufficient uv points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to those obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner funnel of the obscuring torus, is hot (∼800 K), 1.35 parsec long and 0.45 parsec thick in full width at half-maximum (FWHM) at a PA =−42° (from north to east). It has an absorption profile different than standard interstellar dust and with evidence for clumpiness. The second component is 3 × 4 pc in FWHM with T=∼300 K, and we identify it with the cooler body of the torus. The compact component is tilted by ∼45° with respect to the radio jet and has similar size and orientation to the observed water maser distribution. We show how the dust distribution relates to other observables within a few parsec of the core of the galaxy, such as the nuclear masers, the radio jet and the ionization cone. We compare our findings to a similar study of the Circinus galaxy and other relevant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus.

Keywords: techniques: interferometric; galaxies: individual: NGC 1068; galaxies: Seyfert; infrared: galaxies

Journal Article.  11984 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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