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A Mean Density of 112 M⊙ pc?3 for Central Molecular Zone Clumps—Evidences for Shear-enabled Pressure Equilibrium in the Galactic Center
Li,Guang-Xing1; Zhang,Chuan-Peng2,3
2020-07-01
Source PublicationThe Astrophysical Journal
ISSN0004-637X
Volume897Issue:1
AbstractAbstract We carry out a systematic study of the density structure of gas in the Central Molecular Zone (CMZ) in the Galactic center by extracting clumps from the APEX Telescope Large Area Survey of the Galaxy survey at 870 μm. We find that the clumps follow a scaling of m?=?ρ0r3, which corresponds to a characteristic density of (ρ0?=?112 M⊙ pc?3) with a variation of ≈0.5 dex, where we assumed a gas-to-dust mass ratio of 100. This characteristic density can be interpreted as the result of thermal pressure equilibrium between the molecular gas and the warm ambient interstellar medium. Such an equilibrium can plausibly be established since shear has approximately the same strength as self-gravity. Our findings may explain the fact that star formation in the CMZ is highly inefficient compared to the rest of the Milky Way disk. We also identify a population of clumps whose densities are two orders of magnitudes higher in the vicinity of the Sgr B2 region, which we propose are produced by collisions between the clumps of lower densities. For these collisions to occur, processes such as compressive tides probably have created the appropriate condition by assembling the clumps together.
KeywordGalactic center Interstellar medium Star formation Tidal interaction Gravitational collapse
DOI10.3847/1538-4357/ab8c47
Language英语
WOS IDIOP:0004-637X-897-1-ab8c47
PublisherThe American Astronomical Society
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Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/63029
Collection中国科学院国家天文台
Affiliation1.South-Western Institute for Astronomy Research, Yunnan University, Kunming, 650500 Yunnan, People's Republic of China; gxli@ynu.edu.cn
2.National Astronomical Observatories, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China; cpzhang@nao.cas.cn
3.CAS Key Laboratory of FAST, National Astronomical Observatories, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
Recommended Citation
GB/T 7714
Li,Guang-Xing,Zhang,Chuan-Peng. A Mean Density of 112 M⊙ pc?3 for Central Molecular Zone Clumps—Evidences for Shear-enabled Pressure Equilibrium in the Galactic Center[J]. The Astrophysical Journal,2020,897(1).
APA Li,Guang-Xing,&Zhang,Chuan-Peng.(2020).A Mean Density of 112 M⊙ pc?3 for Central Molecular Zone Clumps—Evidences for Shear-enabled Pressure Equilibrium in the Galactic Center.The Astrophysical Journal,897(1).
MLA Li,Guang-Xing,et al."A Mean Density of 112 M⊙ pc?3 for Central Molecular Zone Clumps—Evidences for Shear-enabled Pressure Equilibrium in the Galactic Center".The Astrophysical Journal 897.1(2020).
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