Polarization in Monte Carlo radiative transfer and dust scattering
  polarization signatures of spiral galaxies
  Polarization is an important tool to further the understanding of
interstellar dust and the sources behind it. In this paper we describe our
implementation of polarization that is due to scattering of light by spherical
grains and electrons in the dust Monte Carlo radiative transfer code SKIRT. In
contrast to the implementations of other Monte Carlo radiative transfer codes,
ours uses co-moving reference frames that rely solely on the scattering
processes. It fully supports the peel-off mechanism that is crucial for the
efficient calculation of images in 3D Monte Carlo codes. We develop
reproducible test cases that push the limits of our code. The results of our
program are validated by comparison with analytically calculated solutions.
Additionally, we compare results of our code to previously published results.
We apply our method to models of dusty spiral galaxies at near-infrared and
optical wavelengths. We calculate polarization degree maps and show them to
contain signatures that trace characteristics of the dust arms independent of
the inclination or rotation of the galaxy.
