Near- and mid-infrared imaging polarimetry of NGC 1068

We present the results of a series of observations of the near- and mid-inf rared polarization properties of the type 2 Seyfert galaxy NGC 1068. Our da ta agree well with previously published results in showing the need for a s eparate polarization mechanism in the near-infrared apart from scattering. We find that the predictions of a simple model in which this component aris es through absorptive dichroism caused by aligned grains within the extende d warm (similar to 400 K) dust fit the data reasonably if the obscured back ground source is itself the result of dust emission (at temperature > 1000 K), By considering the change of polarization with wavelength we show that the extinction to this hot dust region is in the range A(V) = 20-40, Consid eration of the observed data then leads us to the conclusion that, if viewe d face-on, NGC 1068 would have a strong near-infrared excess similar to typ e 1 Seyfert galaxies. Comparison with other independent measures of the ext inction to the active nucleus itself leads us to the conclusion that the ho t dust must provide screening equivalent to at least A(V) = 40, and possibl y much higher. We speculate that this component alone may be the 'classical ' torus discussed in terms of the unified model, and the more extensive mid -infrared emission may arise from circumnuclear molecular cloud material, a nd dust in the ionization cones.