Polarized arcs near the Galactic Centre.

We report on the results of a total intensity and polarization survey of the Galactic Center region carried out with the Parkes 64-m telescope at a wavelength of 3.5 cm and an angular resolution of 2.8 x 2.9 arcmin. The main result is the discovery of three arcs of polarized radio emission. Two of the arcs lie to the west and one to the east of Sagittarius A. Their axes lie orthogonal to the galactic plane. We confirm the presence of a major plume or arc structure to the east of Sagittarius A previously observed to abut the galactic plane near 0.2 deg. It is now found to be nearly 2 deg in extent, which is more extensive than previously thought. Another arc, again orthogonal to the galactic plane, lies about 0.4 deg to the west of Sagittarius A. Two smaller arcs may be part of a more extensive feature, again with an axis orthogonal to the plane. One spur of polarized emission leads northeast from the Sagittarius A region; it does not cross the galactic plane.