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 \degr wide strip along the Galactic meridian l = 254 \degr 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 \degr and has weak and smooth polarized emission mostly at large scale with steep angular power spectra of median slope \beta _ { med } \sim - 2.6 .
The disc region covers the latitudes |b| < 20 \degr and has a brighter , more complex emission dominated by the small scales with flatter spectra of median slope \beta _ { 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 \degr with very low emission which , once scaled to 70Â GHz , is equivalent to the CMB B –Mode emission for a tensor–to–scalar perturbation power ratio r _ { halo } = ( 3.3 \pm 0.4 ) \times 10 ^ { -3 } .
Applying a conservative cleaning procedure , we estimate an r detection limit of \delta r \sim 2 \times 10 ^ { -3 } at 70Â GHz ( 3-sigma C.L . )
and , assuming a dust polariztion fraction < Â 12 % , \delta r \sim 1 \times 10 ^ { -2 } at 150Â GHz .
The 150Â GHz limit matches the goals of planned sub-orbital experiments , which can therefore be conducted at this high frequency .
The 70Â GHz limit is close to the goal of proposed next generation space missions , which thus might not strictly require space-based platforms .