A New Perspective of the Radio Bright Zone at The Galactic Center:
  Feedback from Nuclear Activities
  New observations of Sgr A have been carried out with the VLA using the
broadband (2 GHz) continuum mode at 5.5 GHz, covering the central 30 pc region
of the RBZ at the Galactic center. Using the MS-MFS algorithms in CASA, we have
imaged Sgr A with a resolution of 1", achieving an rms 8 $\mu$Jy/beam, and a
dynamic range 100,000:1.The radio image is compared with X-ray, CN
emission-line and Paschen-$\alpha$ images obtained using Chandra, SMA and
HST/NICMOS, respectively. We discuss several prominent radio features. The "Sgr
A West Wings" extend 5 pc from the NW and SE tips of the ionized "Mini-spiral"
in Sgr A West to positions located 2.9 and 2.4 arc min to the NW and SE of Sgr
A*, respectively. The NW wing, along with several other prominent features,
including the "NW Streamers", form an elongated radio lobe (NW lobe), oriented
nearly perpendicular to the Galactic plane. This radio lobe, with a size of
14.4 pc x 7.3 pc, has a known X-ray counterpart. A row of three thermally
emitting rings is observed in the NW lobe. A field containing numerous
amorphous radio blobs extends for a distance of ~2 arc min beyond the tip of
the SE wing; these features coincide with the SE X-ray lobe. Most of the
amorphous radio blobs in the NW and SE lobes have Paschen-$\alpha$
counterparts, suggesting that a shock interaction of ambient gas concentrations
with a collimated nuclear wind (outflow) that may be driven by radiation force
from the central star cluster within the CND. Finally, we remark on a prominent
radio feature located within the shell of the Sgr A East SNR. Because this
feature -- the "Sigma Front" -- correlates well in shape and orientation with
the nearby edge of the CND, we propose that it is a reflected shock wave
resulting from the impact of the Sgr A East blast wave on the CND.
