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An energetic high-velocity compact cloud: CO−0.31+0.11
ABSTRACT We have discovered an energetic high-velocity compact cloud CO$\, -0.31+$0.11 in the central molecular zone of our Galaxy. CO$\, -0.31+$0.11 is located at a projected distance of ∼45 pc from the Galactic nucleus Sgr A*. It is characterized by its compact spatial appearance (d ≃ 4 pc), extre...
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Published in: | Publications of the Astronomical Society of Japan 2019-12, Vol.71 (Supplement_1) |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | ABSTRACT
We have discovered an energetic high-velocity compact cloud CO$\, -0.31+$0.11 in the central molecular zone of our Galaxy. CO$\, -0.31+$0.11 is located at a projected distance of ∼45 pc from the Galactic nucleus Sgr A*. It is characterized by its compact spatial appearance (d ≃ 4 pc), extremely broad velocity width (ΔV > 100 km s−1), and high CO J = 3–2/J = 1–0 intensity ratio. The total gas mass and kinetic energy are estimated as approximately $10^{4}\, M_{\odot }$ and 1051 erg, respectively. Two expanding bubble-like structures are found in our HCN J = 1–0 map obtained with the Nobeyama Radio Observatory 45 m telescope. In the longitude–velocity maps, CO$\, -0.31+$0.11 exhibits an asymmetric V shape. This kinematical structure can be well fitted by Keplerian motion on an eccentric orbit around a point mass of $2\times 10^{5}\, M_\odot$. The enhanced CO J = 3–2/J = 1–0 ratio is possibly attributed to the tidal compression during the pericenter passage. The model suggests that a huge mass is packed within a radius of r < 0.1 pc. The huge mass, compactness, and absence of luminous stellar counterparts may correspond to a signature of an intermediate-mass black hole (IMBH) inside. We propose a formation scenario of CO$\, -0.31+$0.11 in which a compact cloud has gravitationally interacted with an IMBH and a bipolar molecular outflow was driven by the past activity of the putative IMBH. |
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ISSN: | 0004-6264 2053-051X |
DOI: | 10.1093/pasj/psz027 |