Nicmos Polarimetry of "Polar Scattered" Seyfert 1 Galaxies
  The nuclei of Seyfert 1 galaxies exhibit a range of optical polarization
characteristics that can be understood in terms of two scattering regions
producing orthogonal polarizations: an extended polar scattering region (PSR)
and a compact equatorial scattering region (ESR), located within the
circum-nuclear torus. Here we present NICMOS 2.0 micron imaging polarimetry of
6 "polar scattered" Seyfert 1 (S1) galaxies, in which the PSR dominates the
optical polarization. The unresolved nucleus (<0.58 arcsec) is significantly
polarized in only three objects, but 5 of the 6 exhibit polarization in a 0.58
to 1.5 arcsec circum-nuclear annulus. In Fairall 51 and ESO 323-G077, the
polarization position angle at 2 microns (theta2m) is consistent with the
average for the optical spectrum (thetav), implying that the nuclear
polarization is dominated by polar scattering at both wavelengths. The same is
probably true for NGC 3227. In both NGC 4593 and Mrk 766, there is a large
difference between theta2m and thetav off nucleus, where polar scattering is
expected to dominate. This may be due to contamination by interstellar
polarization in NGC 4593, but there is no clear explanation in the case of the
strongly polarized Mrk 766. Lastly, in Mrk 1239, a large change (~ 60deg) in
theta2m between the nucleus and the annulus indicates that the unresolved
nucleus and its immediate surroundings have different polarization states at 2
microns, which we attribute to the ESR and PSR, respectively. A further
implication is that the source of the scattered 2 micron emission in the
unresolved nucleus is the accretion disk, rather than torus hot dust emission.
