演講資訊

摘要：

he interaction between a supermassive black hole (SMBH) and the surrounding material is of primary importance in modern astrophysics. The detection of the molecular 2-pc circumnuclear disk (CND) immediately around the Milky Way SMBH, SgrA*, provides an unique opportunity to study SMBH accretion at subparsec scales. However, the origin and the lifetime of the CND has remained mysterious despite intensive study during the past decades. The CND can not live longer than 10^5 years if its gas density is under the tidal threshold of SgrA*/nuclear star clusters, thus depleting the source of fuel. Our new wide-field CS(J=2-1) map toward the Galactic center (GC) reveals multiple dense molecular streamers originated from the ambient clouds 20-pc further out, and connecting to the central 2 parsecs of the CND. These dense gas streamers appear to carry gas directly toward the nuclear region and might be captured by the central potential. Our phase-plot analysis indicates that these streamers show a signature of “infalling” motion with progressively higher velocities as the gas approaches the CND and finally ends up co-rotating with the CND. Our results might suggest a possible mechanism of gas feeding the CND from 20 pc around 2 pc of the GC. Besides, we also find the outflow motion which might destruct the inflow motion. In this talk, I will discuss the morphology and the kinematics of these streamers feeding the Galactic center . As the nearest observable Galactic nucleus, this feeding process may have implications for understanding the processes in extragalactic nuclei. (also see 2016 ApJ, 831, 72; 2015 ApJ, 811, 142; 2017, ApJ accepted)