SiO Maser Survey in the Galactic Center Region with a Multi-Beam Receiver

Abstract

Abstract We have made a wide-field survey of SiO masers in the $7'' \times 13''$ area around the Galactic center with the Nobeyama 45-m radio telescope using a $2 \times 3$ multi-beam SIS mixer receiver at 43 GHz. We detected 9 SiO maser sources (6 of them are new); newly detected 6 sources have been identified with Miras or OH 1612 MHz maser sources. The source surface number density, $\sim 360$ per square degree, found in this survey is slightly smaller than the number density of OH 1612 MHz sources in the same area. A least-squares analysis of the radial velocities of the detected sources has revealed a rapid rotation of the stars around the Galactic center. This implies that most of the objects detected in this survey belong to the nuclear disk near the Galactic center.