Mid‐Infrared Spectral Energy Distribution of NGC 1068 with 0.̋1 Spatial Resolution

The central region of the Seyfert 2 galaxy NGC 1068 is imaged in the midinfrared (MIR) using the Mid-Infrared Test Observation System on the 8.2 mSubaru Telescope. The oversampling pixel scale associated with shift-and-addmethod shows 0.1 arcsec resolution images with a high dynamic range afterdeconvolution. Along with an extended structure at a position angle (P.A.) of-10 degrees with higher surface brightness, another structure extends widerwith lower surface brightness at a P.A. of 20 degrees. The central peakelongates north-south with FWHM of 0.3 x 0.2 arcsec. Spectral energydistribution (SED) of the central peak is fitted to have the silicateabsorption feature of tau_9.7um = 0.9 +/- 0.3. This is half of the absorptionexpected from the near-infrared (NIR) feature of carbonaceous dust. Thissuggests a temperature gradient of the absorbing dust along the line of sight.Another possibility, which is not distinguishable here, is the sizedistribution of dust different from our Galaxy. Intrinsic luminosity ofemission from the central peak is 3 x 10^37 W. The SED shows a hint of the polyaromatic hydrocarbon (PAH) emission features. Although a high spatialresolution MIR spectrum is required, it suggests that the PAH carriers near theactive galactic nuclei (AGNs) are sheltered from the high-energy emission fromthe AGNs and the AGNs have nuclear starbursts. For the NIR disklike structures,no counterparts are detected in the MIR. The nature of the structures remainsunclear.Comment: 22 pages LaTeX, 5 postscript figures. Printed in ApJ, 2001, vol. 557, p.637. (C) 2001. The American Astronomical Society. All rights reserve