We present the first observation of the diffuse polarized synchrotron
radiation of a patch (∼3∘×3∘) in the BOOMERanG field,
one of the areas with the lowest CMB foreground emission. The work has been
carried out with the Australia Telescope Compact Array at 1.4 GHz with 3.4
arcmin resolution and sensitivity of ∼0.18 mJy beam−1. The mean
polarized signal has been found to be Prms​=(Qrms2​+Urms2​)​=11.6±0.6 mK, nearly one order of magnitude below than in the Galactic
Plane.
Extrapolations to frequencies of interest for cosmological investigations
suggest that polarized synchrotron foreground noise should allow the detection
of the CMB Polarization E--mode already at 32 GHz and make us confident that,
at 90 GHz, it is accessible with no relevant foreground contamination. Last but
not least, even the B--mode detection for T/S>0.01 is not ruled out in
such a low emission patch.Comment: Uses emulateapj.sty, onecolfloat.sty, 5 pages 4 fig., accepted for
publication in ApJ