Dissecting the active galactic nucleus in Circinus -- II. A thin dusty
  disc and a polar outflow on parsec scales
  Recent observations which resolved the mid-infrared (MIR) emission of nearby
active galactic nuclei (AGN), surprisingly revealed that their dust emission
appears prominently extended in the polar direction, at odds with the
expectations from the canonical dusty torus. This polar dust, tentatively
associated with dusty winds driven by radiation pressure, is found to have a
major contribution to the MIR flux from scales of a few to hundreds of parsecs.
When facing a potential change of paradigm, case studies of objects with the
best intrinsic resolution are essential. One such source with a clear detection
of polar dust is a nearby, well-known AGN in the Circinus galaxy. In the first
paper, we successfully explained the peculiar MIR morphology of Circinus
observed on large, tens of parsec scales with a model consisting of a compact
dusty disc and an extended hollow dusty cone. In this work, we further refine
the model on smaller, parsecs scales to test whether it can also explain the
MIR interferometric data. We find that a model composed of a thin dusty disc
seen almost edge-on and a polar outflow in the form of a hyperboloid shell can
reproduce well the VLTI/MIDI observations at all wavelengths, baselines and
position angles. In contrast, while providing a good fit to the integrated MIR
spectrum, the dusty torus model fails to reproduce the spatially resolved
interferometric data. We put forth the disc$+$hyperboloid wind model of
Circinus AGN as a prototype for the dust structure in the AGN population with
polar dust.
