Thermal imaging of dust hiding the black hole in the Active Galaxy NGC
  1068
  In the widely accepted 'Unified Model' solution of the classification puzzle
of Active Galactic Nuclei, the orientation of a dusty accretion torus around
the central black hole dominates their appearance. In 'type-1' systems, the
bright nucleus is visible at the centre of a face-on torus. In 'type-2' systems
the thick, nearly edge-on torus hides the central engine. Later studies
suggested evolutionary effects and added dusty clumps and polar winds but left
the basic picture intact. However, recent high-resolution images of the
archetypal type-2 galaxy NGC 1068 suggested a more radical revision. They
displayed a ring-like emission feature which the authors advocated to be hot
dust surrounding the black hole at the radius where the radiation from the
central engine evaporates the dust. That ring is too thin and too far tilted
from edge-on to hide the central engine, and ad hoc foreground extinction is
needed to explain the type-2 classification. These images quickly generated
reinterpretations of the type 1-2 dichotomy. Here we present new multi-band
mid-infrared images of NGC1068 that detail the dust temperature distribution
and reaffirm the original model. Combined with radio data, our maps locate the
central engine below the previously reported ring and obscured by a thick,
nearly edge-on disk, as predicted by the Unified Model. We also identify
emission from polar flows and absorbing dust that is mineralogically distinct
from that towards the Milky Way centre.
