Simple foreground cleaning algorithm for detecting primordial B-mode
  polarization of the cosmic microwave background
  We reconsider the pixel-based, "template" polarized foreground removal method
within the context of a next-generation, low-noise, low-resolution (0.5 degree
FWHM) space-borne experiment measuring the cosmological B-mode polarization
signal in the cosmic microwave background (CMB). This method was put forward by
the Wilkinson Microwave Anisotropy Probe (WMAP) team and further studied by
Efstathiou et al. We need at least 3 frequency channels: one is used for
extracting the CMB signal, whereas the other two are used to estimate the
spatial distribution of the polarized dust and synchrotron emission. No
external template maps are used. We extract the tensor-to-scalar ratio (r) from
simulated sky maps consisting of CMB, noise (2 micro K arcmin), and a
foreground model, and find that, even for the simplest 3-frequency
configuration with 60, 100, and 240 GHz, the residual bias in r is as small as
Delta r~0.002. This bias is dominated by the residual synchrotron emission due
to spatial variations of the synchrotron spectral index. With an extended mask
with fsky=0.5, the bias is reduced further down to <0.001.
