The polarization of NGC 1068

Open Access
Publisher Website
Google Scholar
Abstract
Broad-band polarimetry of NGC 1068 over the wavelength range 0.36–4.8 µm is presented, together with high-resolution spectropolarimetry of the Hβ, [O III] and Hα, [N II] regions of the spectrum. We recognize several different polarization components and conclude that they can all be accounted for by processes involving dust. Optical continuum polarization and broad features associated with the Balmer emission lines are due to scattering into the line of sight, of radiation from an obscured Seyfert I nucleus. We argue that the scattering is probably by dust in the narrow line region (NLR), but cannot exclude the possibility of electron scattering. Polarization of the forbidden lines is interpreted as due to the passage of the radiation through aligned grains in the NLR. The 10 µm polarization is due to thermal emission from the same grains. Polarization in the near infrared is probably caused by aligned grains in the thick obscuring dust through which the radiation must pass, but could alternatively be due to nonthermal processes in the nucleus itself.

This publication has 0 references indexed in Scilit: