Off-axis irradiation and the polarization of broad emission lines in
  active galactic nuclei
  The STOKES Monte Carlo radiative transfer code has been extended to model the
velocity dependence of the polarization of emission lines. We use STOKES to
present improved modelling of the velocity-dependent polarization of broad
emission lines in active galactic nuclei. We confirm that off-axis continuum
emission can produce observed velocity dependencies of both the degree and
position angle of polarization. The characteristic features are a dip in the
percentage polarization and an S-shaped swing in the position angle of the
polarization across the line profile. Some differences between our STOKES
results and previous modelling of polarization due to off-axis emission are
noted. In particular we find that the presence of an offset between the maximum
in line flux and the dip in the percentage of polarization or the central
velocity of the swing in position angle does not necessarily imply that the
scattering material is moving radially. Our model is an alternative scenario to
the equatorial scattering disk described by Smith et al. (2005). We discuss
strategies to discriminate between both interpretations and to constrain their
relative contributions to the observed velocity-resolved line and polarization.
