Astron. Astrophys. 363, 926-932 (2000)

0.6 resolution images at 11 and 20 µm of the active galactic nucleus in NGC 1068 ^*

D. Alloin ¹, E. Pantin ², P.O. Lagage ² and G.L. Granato <sup>3

1</sup> European Southern Observatory, Casilla 19001, Santiago, Chile
² DSM/DAPNIA/Service d'Astrophysique, CEA/Saclay, 91191 Gif-sur-Yvette, France
³ Osservatorio Astronomico di Padova, 35122 Padova, Italy

Received 8 August 2000 / Accepted 8 August 2000

Abstract

We present diffraction-limited IR images at 11.2 and 20.5 µm of the central region in NGC 1068, collected with the CAMIRAS instrument mounted at the f/36 IR focus of the CFHT/Hawaii 3.6m telescope and at the f/35 IR focus of the ESO/La Silla 3.6m telescope, respectively. After deconvolution, the achieved resolution () reveals a prominent central core emitting about 95% of the total flux at these wavelengths, as well as extended emission, to the South-West (PA = 210^o) and to the North-East (PA = 35^o), broken into patchy components which are particularly conspicuous at 20.5 µm and can be isolated as individual clouds. The central core shows an East-West FWHM of (hence unresolved) and a North-South FWHM of corresponding to a resolved full size extension of 100 pc. Such an elongated shape is in agreement with model predictions of a dusty/molecular torus surrounding the central engine in NGC 1068, observed under an inclination angl of around 65^o. Considering that the core at 11.2 and 20.5 µm is coincident with the core also seen at 2.2, 3.5 and 4.8 µm and that this features the location of the central engine (also the radio source S1), the extended mid-IR emission is found to follow closely the radio jet-like structure in both the North-East and South-West quadrants. In the North-East quadrant, we observe that the mid-IR emission arises predominantly on the eastern side of the ionizing cone defined by the HST NLR [OIII]-emitting clouds and is still quite prominent at the wide base of the so-called Northeast radio lobe, away from the central engine. A detailed comparison of the extended mid-IR emission with model predictions requires that future AGN modeling includes both a molecular/dusty torus and a distribution of material away from the equatorial plane of the torus, i.e. in and around the NLR.

Key words: galaxies: individual: NGC 1068 galaxies: Seyfert galaxies: nuclei galaxies: active infrared: galaxies

* Based on observations collected at the ESO/La Silla 3.6m telescope, Proposal 62.P-0445, and at the CFHT/Hawaii 3.6m telescope.

Send offprint requests to: D. Alloin (dalloin@eso.org)

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Contents

• 1. Introduction
• 2. Data collection and reduction
• 3. Results and discussion
  • 3.1. Structure and flux contributions
  • 3.2. Comparison with maps at other wavelengths
  • 3.3. Nature of the mid-IR core
  • 3.4. Origin of the extended structure
  • 3.5. Concluding remarks
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: December 5, 2000
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