演講資訊

摘要：

The interaction between a supermassive black hole (SMBH) and the surrounding material is of primary importance in astrophysics. The detection of the molecular 2-pc circumnuclear disk (CND) immediately around the Milky Way SMBH, SgrA*, resembles the "molecular torus" in AGNs, provides an unique opportunity to study SMBH accretion at sub-parsec scales. However, the CND is transient if its gas density is under the tidal threshold of SgrA*/nuclear star clusters, thus depleting the source of fuel. In our new CS line maps, we find several dense gas streamers appear to carry gas directly toward the nuclear region and might be captured by the central potential. These streamers show a signature of “infalling” motion with progressively higher velocities as the gas approaches the CND and finally end up co-rotating with the CND. Furthermore, utilizing the JCMT 850 um polarization data, we also find that the magnetic field appears dynamically significant toward the CND and also onwards to the inward ionized flows. Our results might suggest a possible mechanism of gas feeding to the CND. I will also talk about the observed morphology, kinematics of gas, and effects of magnetic fields in the GC. I will present our newest ALMA CS line maps in this region and discuss the gravitational stability of molecular cloud cores near Sgr A*.. As the nearest observable Galactic nucleus, this feeding process may have implications for understanding the processes in extragalactic nuclei.