Mid-infrared imaging of NGC 1068 with VISIR at the Very Large Telescope

High-resolution mid-infrared (MIR) images of the central region of NGC 1068 have been obtained with VISIR, the multi-mode MIR instrument recently installed at the European Southern Observatory Very Large Telescope on Paranal. A map of the emission at 12.8 mu m with increased sensitivity over the central 8 x 8 arcsec(2) area is discussed. It shows a central core (unresolved along the east-west direction) and extended emission which has a spiral pattern similar to that observed in near-infrared images. Patches of MIR emission can be detected up to a distance of 4 arcsec from the core. The deconvolved 12.8-mu m map is fully consistent with previous high-resolution MIR observations. It highlights the structure of the extended emission, already seen in the un-deconvolved image, and allows us to identify a set of MIR sources: seven in the north-eastern quadrant and five in the south-western quadrant. The MIR emission map is compared with those obtained at comparable angular resolution in the near-infrared and in [O III] line emission. The very good correlation between the VISIR map and the Hubble Space Telescope optical map supports the idea that the MIR emission not associated with the torus arises from dust associated with the narrow-line-region clouds. The north-south extension of the MIR core (0.44 arcsec) is then probably simply due to the mixing of the MIR emission from the dusty torus and the MIR emission from narrow-line-region cloud B, located only 0.1 arcsec to the north.