The molecular gas feeding the Galactic center - an excellent laboratory to understand supermassive black hole feeding

Colloquium

Astronomy Colloquium (2017 Spring Semester)

* Date: May 25
* Speaker: Pei-Ying Hsieh (ASIAA)
* Title: The molecular gas feeding the Galactic center – an excellent laboratory to understand supermassive black hole feeding
* Abstract

The 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 sustain over 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. 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.

Date	Speaker	Title	Remarks
Mar 02	Chris Belczynski (Warsaw University Observatory)	The ongoing LIGO search for gravitational-waves: BH-BH modeling
Mar 09	Jeongwoo Lee (Institute for Space-Earth Environmental Research, Nagoya University)	When the Sun’s Coronal Tail Wags Its Photospheric Dog
Mar 16	Hongjun An (CBNU)	High-energy astrophysics in the X-ray and GeV energies
Mar 23	KASI ALMA Group	ALMA Town Meeting
Mar 30	Ken Chen (NAOJ, Japan)	Lighting up the Universe with Extreme Supernovae
Apr 06	Guangyao Zhao (KASI)	Multi-frequency mm-VLBI observations of AGNs with KVN
Apr 11	Tarun Souradeep (IUCAA Pune, India)	Rugged but enigmatic post-Planck Cosmos	Tuesday
Apr 20	Tugca Sener (KASI)	Hot subdwarf stars in binaries
Apr 27	Benjamin L’Huillier (KASI)	Numerical simulations of structure formation: LCDM and beyond
May 04	TBD	TBD
May 11	Thiem Hoang (KASI)	New Insights into the Role and Importance of Interstellar Nanoparticles
May 18	Ho Jung Paik (U Maryland)	Superconducting Gravitational Wave Detector For Observation in Infrasound Frequency Band
May 23	Kwang-Ho Park (Georgia Tech)	Feedback-regulated fueling of massive black holes	Tuesday
May 25	Pei-Ying Hsieh (ASIAA)	The molecular gas feeding the Galactic center – an excellent laboratory to understand supermassive black hole feeding
May 30	Andreas Schulze (NAOJ)	New constraints on the black hole spin in radio-loud quasars	Tuesday
Jun 01	Mijin Yoon (Yonsei University)	Testing the statistical isotropy using dipolar modulation in galaxy number counts
Jun 08	Juan Carlos Algaba Marcos (KASI)	Exploring the variability of the flat spectrum radio source 1633+382
Jun 16	Takahiro Hiroi (Brown University)	Asteroid-Meteorite Reflectance Spectroscopy, Space Weathering, and Hayabusa Missions	Friday

2017 Spring semester detail