ALMA Observations of Massive Clouds in the Central Molecular Zone: External-pressure-confined Dense Cores and Salpeter-like Core Mass Functions

Abstract We present Atacama Large Millimeter/submillimeter Array Band 6 (1.3 mm) observations of dense cores in three massive molecular clouds within the central molecular zone (CMZ) of the Milky Way, including the Dust Ridge cloud e, Sgr C, and the 20 km s −1 cloud, at a spatial resolution of 2000 au. Among the 834 cores identified from the 1.3 mm continuum, we constrain temperatures and linewidths of 253 cores using local thermodynamic equilibrium methods to fit the H 2 CO and/or CH 3 CN spectra. We determine their masses using the 1.3 mm dust continuum and derived temperatures, and then evaluate their virial parameters using the H 2 CO and/or CH 3 CN linewidths and construct the core mass functions (CMFs). We find that the contribution of external pressure is crucial for the virial equilibrium of the dense cores in the three clouds, which contrasts with the environment in the Galactic disk where dense cores are already bound, even without the contribution of external pressure. With our new temperature estimates we also find that the CMFs show a Salpeter-like slope in the high-mass (≳3–6 M ⊙ ) end, a change from previous works. Combined with the possible top-heavy initial mass functions (IMFs) in the CMZ, our result suggests that gas accretion and further fragmentation may play important roles in transforming the CMF to the IMF.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-02-03
DOI
https://doi.org/10.3847/1538-4357/ad9f28
Citations
4
Primary Topic
Astrophysics and Star Formation Studies
Type
article
Field-Weighted Citation Impact
4.62

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article

ALMA Observations of Massive Clouds in the Central Molecular Zone: External-pressure-confined Dense Cores and Salpeter-like Core Mass Functions

Xiaofeng Mai, Xindi Tang, Tie Liu, Jens Kauffmann et al.
4 citations
The Astrophysical Journal
Astrophysics and Star Formation Studies
4.62
article

ALMA Observations of Massive Clouds in the Central Molecular Zone: External-pressure-confined Dense Cores and Salpeter-like Core Mass Functions

Xiaofeng Mai, Xindi Tang, Tie Liu, Jens Kauffmann, Xunchuan Liu, Suinan Zhang, Shanghuo Li, Zhi-Qiang Shen, Hauyu Baobab Liu, Fengwei Xu, Yu Cheng, Xianjin Shen, Adam Ginsburg, Wenyu Jiao, Xing Lu, Daniel L. Walker, Qiuyi Luo, Cara Battersby, Sheng‐Li Qin, Qilao Gu, T. Pillai, Siyi Feng, Meizhu Liu, Li Chen, Qizhou Zhang, Zhenying 朕荧 Zhang 张, Zi-yang 紫杨 Li 李, Dongting 东庭 Yang 杨
article en
4 citations

Abstract

Abstract We present Atacama Large Millimeter/submillimeter Array Band 6 (1.3 mm) observations of dense cores in three massive molecular clouds within the central molecular zone (CMZ) of the Milky Way, including the Dust Ridge cloud e, Sgr C, and the 20 km s −1 cloud, at a spatial resolution of 2000 au. Among the 834 cores identified from the 1.3 mm continuum, we constrain temperatures and linewidths of 253 cores using local thermodynamic equilibrium methods to fit the H 2 CO and/or CH 3 CN spectra. We determine their masses using the 1.3 mm dust continuum and derived temperatures, and then evaluate their virial parameters using the H 2 CO and/or CH 3 CN linewidths and construct the core mass functions (CMFs). We find that the contribution of external pressure is crucial for the virial equilibrium of the dense cores in the three clouds, which contrasts with the environment in the Galactic disk where dense cores are already bound, even without the contribution of external pressure. With our new temperature estimates we also find that the CMFs show a Salpeter-like slope in the high-mass (≳3–6 M ⊙ ) end, a change from previous works. Combined with the possible top-heavy initial mass functions (IMFs) in the CMZ, our result suggests that gas accretion and further fragmentation may play important roles in transforming the CMF to the IMF.

The Astrophysical JournalVol. 980(1)
National Aeronautics and Space Administration, Science and Technology Facilities Council
Openalex Percentile: Top 7%
Astrophysics and Star Formation Studies
4.62
DOIOpen Access PDFOpenAlex
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