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

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 reso...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2009-04, Vol.394 (3), p.1325-1337
Main Authors: Raban, David, Jaffe, Walter, Röttgering, Huub, Meisenheimer, Klaus, Tristram, Konrad R. W.
Format: Article
Language:English
Subjects:
Astronomy
Dust
Earth, ocean, space
Exact sciences and technology
galaxies: individual: NGC 1068
galaxies: Seyfert
Infrared imaging systems
Infrared radiation
infrared: galaxies
Stars & galaxies
techniques: interferometric
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Summary: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.
ISSN:0035-8711
1365-2966
DOI:10.1111/j.1365-2966.2009.14439.x