The Parkes Galactic Meridian Survey (PGMS): observations and CMB
  polarization foreground analysis
  We present observations and CMB foreground analysis of the Parkes Galactic
Meridian Survey (PGMS), an investigation of the Galactic latitude behaviour of
the polarized synchrotron emission at 2.3 GHz with the Parkes Radio Telescope.
The survey consists of a 5-deg wide strip along the Galactic meridian l=254-deg
extending from Galactic plane to South Galactic pole. We identify three zones
distinguished by polarized emission properties: the disc, the halo, and a
transition region connecting them. The halo section lies at latitudes |b| >
40-deg and has weak and smooth polarized emission mostly at large scale with
steep angular power spectra of median slope $\beta_{\rm med} \sim -2.6$. The
disc region covers the latitudes |b|<20-deg and has a brighter, more complex
emission dominated by the small scales with flatter spectra of median slope
$\beta_{\rm med} = -1.8$. The transition region has steep spectra as in the
halo, but the emission increases toward the Galactic plane from halo to disc
levels. The change of slope and emission structure at $b \sim -20\degr$ is
sudden, indicating a sharp disc-halo transition. The whole halo section is just
one environment extended over 50-deg with very low emission which, once scaled
to 70GHz, is equivalent to the CMB B-Mode emission for a tensor-to-scalar
perturbation power ratio r_halo = 3.3 +/- 0.4 x 10^{-3}. Applying a
conservative cleaning procedure, we estimate an r detection limit of $\delta r
\sim 2\times 10^{-3}$ at 70~GHz (3-sigma C.L.) and, assuming a dust polariztion
fraction <12%, $\delta r \sim 1\times 10^{-2}$ at 150~GHz. The 150-GHz limit
matches the goals of planned sub-orbital experiments, which can therefore be
conducted at this high frequency. The 70-GHz limit is close to the goal of
proposed next generation space missions, which thus might not strictly require
space-based platforms.
