Unveiling polarized emission from interstellar dust of the Large
  Magellanic Cloud with Planck
  Polarization of interstellar dust emission is a powerful probe of dust
properties and magnetic field structure. Yet studies of external galaxies are
hampered by foreground dust contribution. The aim of this study is to separate
the polarised signal from the Large Magellanic Cloud (LMC) from that of the
Milky Way (MW) in order to construct a wide-field, spatially complete map of
dust polarization using the Planck 353 GHz data. To estimate the foreground
polarization direction, we used velocity gradients in HI spectral line data and
assessed the performance of the output by comparing to starlight extinction
polarization. We estimate the foreground intensity using dust properties
derived previously from the Planck data and we assume the foreground
polarization to be uniform and equal to the average of the MW around the
galaxy. After foreground removal, the geometry of the plane-of-the-sky magnetic
field in the LMC tends to follow the structure of the atomic gas in the LMC.
This is notably the case along the molecular ridges extending south and
south-east of the 30 Doradus star-forming complex, and along more diffuse
southern arm extending towards the Small Magellanic Cloud. There is also an
alignment between the magnetic field and the outer arm in the western part. The
median polarization fraction in the LMC is slightly lower than that observed
for the MW while the anti-correlation between the polarization angle dispersion
function and the polarization fraction is slightly larger. Overall,
polarization fraction distribution is similar to that observed in the MW.
