Impact of Galactic polarized emission on B-mode detection at low
  multipoles
  We use a model of polarized Galactic emission developed by the the Planck
collaboration to assess the impact of foregrounds on B-mode detection at low
multipoles. Our main interest is to applications of noisy polarization data and
in particular to assessing the feasibility of B-mode detection by Planck. This
limits the complexity of foreground subtraction techniques that can be applied
to the data. We analyze internal linear combination techniques and show that
the offset caused by the dominant E-mode polarization pattern leads to a
fundamental limit of r approximately 0.1 for the tensor-scalar ratio even in
the absence of instrumental noise. We devise a simple, robust, template fitting
technique using multi-frequency polarization maps. We show that template
fitting using Planck data alone offers a feasible way of recovering primordial
B-modes from dominant foreground contamination, even in the presence of noise
on the data and templates. We implement and test a pixel-based scheme for
computing the likelihood function of cosmological parameters at low multipoles
that incorporates foreground subtraction of noisy data.
