Near-infrared imaging polarimetry of NGC 1068

Abstract

We present near-infrared polarization images of the nuclear region of NGC 1068. For the first time, extended reflection nebulosity from the south-western cone, which is obscured at optical wavelengths, is detected. Polarized flux images show the region of enhanced scattering, or polarized knot, ~4.5arcsec north-east of the nucleus. Our photometry of the nucleus shows an increase in luminosity compared with earlier observations, which is consistent with the brightening recently reported by Glass. We have successfully adapted the nuclear aperture model of Young et al. to fit the polarized flux images. We find that the basic geometrical parameters of inclination (43 deg), position angle (PA, 34 deg) and opening half-angle (40 deg) of the scattering cones are entirely consistent with our earlier model, with the north-eastern cone having the same PA as the large-scale radio structure. However, an inner scattering cone of inclination 34 deg, PA 10 deg and opening half-angle of 15 deg is required to fit the observed polarized flux distribution to the north-east of the nucleus. This inner cone has the same PA as that of the small-scale (subarcsec) radio jet between sources S and C, implying that source S is the radio source closest to the central engine. Such a cone to the south-west of the nucleus is presumably obscured by the torus.