Mid-infrared imaging- and spectro-polarimetric subarcsecond observations
  of NGC 1068
  We present sub-arcsecond 7.5$-$13 $\mu$m imaging- and spectro-polarimetric
observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio
CANARIAS. At all wavelengths, we find:
  (1) A 90 $\times$ 60 pc extended polarized feature in the northern ionization
cone, with a uniform $\sim$44$^{\circ}$ polarization angle. Its polarization
arises from dust and gas emission in the ionization cone, heated by the active
nucleus and jet, and further extinguished by aligned dust grains in the host
galaxy. The polarization spectrum of the jet-molecular cloud interaction at
$\sim$24 pc from the core is highly polarized, and does not show a silicate
feature, suggesting that the dust grains are different from those in the
interstellar medium.
  (2) A southern polarized feature at $\sim$9.6 pc from the core. Its
polarization arises from a dust emission component extinguished by a large
concentration of dust in the galaxy disc. We cannot distinguish between dust
emission from magnetically aligned dust grains directly heated by the jet close
to the core, and aligned dust grains in the dusty obscuring material
surrounding the central engine. Silicate-like grains reproduce the polarized
dust emission in this feature, suggesting different dust compositions in both
ionization cones.
  (3) An upper limit of polarization degree of 0.3 per cent in the core. Based
on our polarization model, the expected polarization of the obscuring dusty
material is $\lesssim$0.1 per cent in the 8$-$13 $\mu$m wavelength range. This
low polarization may be arising from the passage of radiation through aligned
dust grains in the shielded edges of the clumps.
