We present so far the highest resolution (∼0.04") ALMA 1.3 mm continuum observations of three massive star-forming clumps in the Central Molecular Zone, namely 20 km s−1 C1, 20 km −1 C4, and Sgr C C4, which reveal prevalent compact millimeter emission. We extract the compact emission with astrodendro and identify a total of 199 fragments with a typical size of ∼370 AU, which represent the first sample of candidates of protostellar envelopes and disks and kernels of prestellar cores in these clumps that are likely forming star clusters. Compared with the protoclusters in the Galactic disk, the three protoclusters display a higher level of hierarchical clustering, likely a result of the stronger turbulence in the CMZ clumps. Compared with the mini-starbursts in the CMZ, Sgr B2 M and N, the three protoclusters also show stronger subclustering in conjunction with a lack of massive fragments. The efficiency of high-mass star formation of the three protoclusters is on average one order of magnitude lower than that of Sgr B2 M and N, despite a similar overall efficiency of converting gas into stars. The lower efficiency of high-mass star formation in the three protoclusters is likely attributed to hierarchical cluster formation.
@article{arxiv.2503.00878,
title = {Subclustering and Star Formation Efficiency in Three Protoclusters in the Central Molecular Zone},
author = {Suinan Zhang and Xing Lu and Adam Ginsburg and Nazar Budaiev and Yu Cheng and Hauyu Baobab Liu and Tie Liu and Qizhou Zhang and Keping Qiu and Siyi Feng and Thushara Pillai and Xindi Tang and Elisabeth A. C. Mills and Qiuyi Luo and Shanghuo Li and Namitha Issac and Xunchuan Liu and Fengwei Xu and Jennifer Wallace and Xiaofeng Mai and Yan-Kun Zhang and Cara Battersby and Steven N. Longmore and Zhiqiang Shen},
journal= {arXiv preprint arXiv:2503.00878},
year = {2025}
}
Comments
11 pages, 3 figures, 2 tables, accepted for publication in the ApJL