Parsec-scale SiO Emission in the Galactic Center

Abstract The central 5 pc of our Galactic center is rich in various molecular tracers. The region is observed to be hot, highly ionized, and volatile, resulting in complex chemistry and kinematics. Countless molecular observations of the central region orbiting the central supermassive black hole Sgr A * have revealed a stable grouping of clouds with a disklike structure known as the circumnuclear disk (CND) orbiting Sgr A * between 1.5 and 3 pc. The CND houses the densest population of gas outside the ionized streams in the minispiral falling onto Sgr A * . However, the small-scale kinematics of the clouds and gas are poorly understood in this region. In this paper, we report single-dish SiO (1–0) observations of the central 5 pc surrounding Sgr A * taken with the Green Bank Telescope. Most of the SiO (1–0) traces the Southern Streamer and Sgr A East—neither of which are associated with the CND. However, one region in the CND, known as the Northeast (NE) Arm, shows high-intensity SiO emission unlike in the rest of the CND, indicating the NE Arm as a candidate region of either cloud–cloud collision or early star formation. Further high-resolution observations of the region are needed to distinguish between the two scenarios.