TY - JOUR
T1 - PHYSICAL CONTACT between the +20 km s-1 CLOUD and the GALACTIC CIRCUMNUCLEAR DISK
AU - Takekawa, Shunya
AU - Oka, Tomoharu
AU - Tanaka, Kunihiko
N1 - Funding Information:
We are grateful to the Nobeyama Radio Observatory (NRO) staff for their excellent support of the 45m telescope observations. The NRO is a branch of the National Astronomical Observatory of Japan, National Institutes of Natural Sciences. We thank the anonymous referee for helpful comments and suggestions that improved this paper. This study was supported by a Grant-in-Aid for Research Fellow from the Japan Society for the Promotion of Science (15J04405).
PY - 2017/1/10
Y1 - 2017/1/10
N2 - This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Galaxy has been imaged in the HCN J = 1-0, HCO+ J = 1-0, CS J = 2-1, H13CN J = 1-0, SiO J = 2-1, SO N J = 23-12, and HC3N J = 11-10 lines using the Nobeyama Radio Observatory 45 m radio telescope. Based on our examination of the position-velocity maps of several high-density probe lines, we have found that an emission "bridge" may be connecting the +20 km s-1 cloud (M-0.13-0.08) and the negative-longitude extension of the CND. Analyses of line intensity ratios imply that the chemical property of the bridge is located between the +20 km s-1 cloud and the CND. We introduce a new interpretation that a part of the CND may be colliding with the 20 km s-1 cloud and the collision may be responsible for the formation of the bridge. Such collisional events could promote mass accretion onto the CND or into the inner ionized cavity, which may be further tested by proper motion studies.
AB - This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Galaxy has been imaged in the HCN J = 1-0, HCO+ J = 1-0, CS J = 2-1, H13CN J = 1-0, SiO J = 2-1, SO N J = 23-12, and HC3N J = 11-10 lines using the Nobeyama Radio Observatory 45 m radio telescope. Based on our examination of the position-velocity maps of several high-density probe lines, we have found that an emission "bridge" may be connecting the +20 km s-1 cloud (M-0.13-0.08) and the negative-longitude extension of the CND. Analyses of line intensity ratios imply that the chemical property of the bridge is located between the +20 km s-1 cloud and the CND. We introduce a new interpretation that a part of the CND may be colliding with the 20 km s-1 cloud and the collision may be responsible for the formation of the bridge. Such collisional events could promote mass accretion onto the CND or into the inner ionized cavity, which may be further tested by proper motion studies.
KW - Galaxy: center
KW - ISM: molecules
KW - galaxies: nuclei
KW - radio lines: ISM
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U2 - 10.3847/1538-4357/834/2/121
DO - 10.3847/1538-4357/834/2/121
M3 - Article
AN - SCOPUS:85010433195
SN - 0004-637X
VL - 834
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 121
ER -