High Spatial Resolution Imaging of NGC 1068 in the Mid-Infrared

Abstract

Mid-infrared observations of the central source of NGC 1068 have been obtained with a spatial resolution in the deconvolved image of 0."1 (~7 pc). The central source is extended by ~1'' in the north-south direction but appears unresolved in the east-west direction over most of its length. About 2/3 of its flux can be ascribed to a core structure that is itself elongated north-south and does not show a distinct unresolved compact source. The source is strongly asymmetric, extending significantly farther to the north than to the south. The morphology of the mid-infrared emission appears similar to that of the radio jet and has features which correlate with the images in [O III]. Its 12.5–24.5 μm color temperature ranges from 215 to 260 K and does not decrease smoothly with distance from the core. Silicate absorption is strongest in the core and to the south and is small in the north. The core, apparently containing 2/3 of the bolometric luminosity of the inner 4'' diameter area, may be explained by a thick, dusty torus near the central active galactic nucleus (AGN) viewed at an angle of ~65° to its plane. There are, however, detailed difficulties with existing models, especially the narrow east-west width of the thin extended mid-infrared "tongue" to the north of the core. We interpret the tongue as reprocessed visual and ultraviolet radiation that is strongly beamed and that originates in the AGN.

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