SiO and H13CO+ Emission Lines Observations Toward the Infalling Gas onto the CND at the Galactic Center

Abstract. The central region of our Galaxy (Sgr A∗) is the nearest galactic center harboring a massive black hole. The environment around Sgr A∗ is a topic of interest in diverse fields. We have studied the gas feeding from giant molecular clouds (GMC) within 10 pc of the Galactic center to the Circumnuclear Ring (CND), which is presumable is infalling gas toward Sgr A∗. In order to study the mechanism, we observed SiO (J=2-1 v=0) and HCO (J=1-0) lines using the Nobeyama Millimeter Array (NMA). We detected the CND clearly in SiO line. The molecular gas in the CND rotates interactively. We observed two molecular streamers within CND in SiO line. One is a new detection. The line intensity ratios at overlapping points of the streamers in the CND are significantly higher (I(SiO)/I(HCO) > 8) than the average of other lines in the CND (about 2-4). This is a strong evidence indicating these streamers are associated with the CND.