ALMA View of the Circum-nuclear Disk of the Galactic Center;
  Tidally-disrupted Molecular Clouds falling to the Galactic Center
  We present the high angular resolution and high sensitivity images of the
"Circum-Nuclear Disk (CND)" and its surrounding region of Milky Way Galaxy in
the CS J=2-1, SiO v=0 J=2-1, H^13CO^+ J=1-0, C^34S J=2-1, and CH_3OH J_{K_a,
K_c}=2_{1,1}-1_{1,0}A_{--} emission lines using ALMA. The CND is recognized as
a torus-like molecular gas with gaps in these emission lines except for the
CH_3OH emission line. The inner and outer radii of the CND are estimated to be
R_in~1.5 and R_out~2 pc, respectively. The velocities of the rotation and
radial motion are estimated to be V_rot~115 km s^-1 and V_rad~23 km s^-1,
respectively. The LTE molecular gas mass is estimated to be M_LTE~3x10^4 Mo. We
also found some anomalous molecular clouds in the surrounding region. One of
the molecular clouds is positionally connected to a part of the CND adjacent to
the "Western Arc". However, the cloud is seen to rotate in the opposite
direction to the CND. The molecular cloud would be falling currently from the
outer region to the CND and being disrupted by the tidal shear of Sagittarius
A*(Sgr A*) because the velocity is not yet assimilated into that of the CND.
Another molecular cloud is continuously connected to the tip of the "Eastern
Arm (EA)". The velocity of this cloud is consistent with that of the ionized
gas in the EA. These facts suggest that the molecular cloud is falling from the
outer region to the vicinity of Sgr A*, being disrupted by the tidal shear, and
ionized by strong UV emission from the Central Cluster because the impact
parameter of the cloud is smaller than the first cloud. These falling clouds
would play an important role in transferring material from the outer region to
the CND and/or the vicinity of Sgr A*.
