(Proposal ID) S13B-012

(PI) Nishiyama, Shogo

(Proposal Title)
Gas Cloud Accretion onto the SMBH SgrA^* and Formation of Jet

(Abstract)
A dense gas cloud is rapidly approaching the Galactic supermassive black hole 
(SMBH) SgrA^*, and will be ~ 2,200 Schwarzschild radii from the SMBH at the 
pericenter of its eccentric orbit in Sep 2013. The cloud is expected to be 
disrupted by instabilities and tidal forces, and the cloud fragments accrete 
onto the SMBH on the dynamical timescale of several days to several weeks, 
suggesting a jet formation in 2013. So we are carrying out daily monitoring 
observations of SgrA^* in near-infrared and radio wavelengths, and we propose 
quick follow-up observations with Subaru/Gemini. Br-gamma line emission maps 
obtained with Gemini/NIFS will be used to fine tune our 3D simulation to 
estimate how much mass is, and when the fragment is accreted onto the SMBH. 
Polarimetric signals from a jet taken with Subaru/HiCIAO will be compared with 
the finely tuned simulation to understand the timescale of a jet formation, 
and to investigate the correlation between the accreted mass of the cloud 
fragment and a luminosity of a newly-formed jet. Spectroscopic and imaging 
observations from 1.6 - 11 mum (Subaru/IRCS, COMICS) will also be conducted to 
understand processes responsible for near to mid-infrared emission during the 
accretion event.