Sgr A West: Its Kinematics and Its Role as a Possible Source of Scattering Sgr A$^*$ at the Galactic Center
Session 54 -- MW, Galactic Structure
Oral presentation, Wednesday, 10:30-12:00, Dwinelle 155 Room

## [54.04] Sgr A West: Its Kinematics and Its Role as a Possible Source of Scattering Sgr A$^*$ at the Galactic Center

F. Yusef-Zadeh, M. Wardle (Northwestern U.), W. Cotton, M. Goss, C. Walker, J.-H. Zhao (NRAO), F. Melia (U. Arizona})

We present two sets of new radio observations of the Galactic center to learn about the kinematics of ionized gas associated with the inner two pcs of the Galaxy and to address the possible role of this ionized medium in scattering radio continuum radiation emerging from the compact radio source (Sgr A$^*$) at the Galactic center.

The first set of observations is related to measurements of radio recombination line (RRL), H110$\alpha$, emission from Sgr A West with a resolution of 11''$\times20$''. These relatively low-resolution observations detected new RRL emission from large-scale features showing a deviation from circular motion. The origin of this non-circular moving gas is not understood but we consider the possibility that it may be produced as a result of the dynamical interaction of winds from the Galactic center.

The second set of observations are based on VLA and VLBA measurements of Sgr A$^*$ at $\lambda$20 and 1.3cm, respectively. The Gaussian fit to this resolved source at $\lambda$20cm gives a source size of 0.59$''\times0.23''$, PA=80$^0$. While the axial ratio at $\lambda$20cm appears to be higher than at higher frequencies, the direction of the elongation is quite similar to VLBA measurements of Sgr A$^*$ at $\lambda$1.3cm. We consider a number of possibilities for the origin of the elongation of Sgr A$^*$.