Publications of the MPIfR
Optical & Infrared
Interferometry Group
Weigelt, G., Beckert, T., Hofmann,
K.-H., Schertl, D., Wittkowski, M.
NIR interferometry of the Seyfert galaxy NGC
1068: present interferometric results and future goals
37th Liège International Astrophysical Colloquium,
p.97-104 (2005)
Abstract
We discuss present results and future goals of near-infrared interferometry of NGC 1068. We show that infrared interferometry is able to resolve the innermost, sub-parsec-scale dust environment surrounding the accretion disk. A diffraction-limited K’-band image of NGC 1068 with 74 mas resolution and the first H-band image with 57 mas resolution were reconstructed from speckle interferograms obtained with the SAO 6m telescope. The resolved structure consists of a compact core and an extended northern and south-eastern component. The compact core has a north-western, tail-shaped extension as well as a fainter, south-eastern extension. The K’-band FWHM diameter of this compact core is approximately 18×39 mas or 1.3×2.8 pc, and the position angle (PA) of the north-western extension is -16. The extended northern component (PA ~ 0◦) has an elongated structure with a length of about 400 mas or 29 pc. The PA of –16◦ of the compact 18×39 mas core is very similar to that of the western wall (PA ~ –15◦) of the ionization cone. This suggests that the H- and K’-band emission from the compact core is both thermal emission and scattered light from dust near the western wall of a low-density, conical outflow cavity or from the innermost region of a parsec-scale dusty torus that is heated by the central source (the dust sublimation radius of NGC 1068 is approximately 0.1 – 1 pc). The first near-infrared K-band long-baseline interferometry of the nucleus of NGC 1068 with resolution λ/B ~ 10 mas was obtained with the ESO VLTI. A squared visibility amplitude of 16.3 ± 4.3% was measured for NGC 1068 at a sky-projected baseline length of 45.8 m. Taking into account K-band speckle interferometry observations, the VLTI observations suggest a multi-component structure for the intensity distribution, where part of the flux originates from scales clearly smaller than ~ 5 mas (≤ 0.4 pc).
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