ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- V. Hierarchical fragmentation and gas dynamics in IRDC G034.43+00.24

Hong-Li Liu, Anandmayee Tej, Tie Liu, Namitha Issac, Anindya Saha, Paul F. Goldsmith, Jun-Zhi Wang, Qizhou Zhang, Sheng-Li Qin, Ke Wang, Shanghuo Li, Archana Soam, Lokesh Dewangan, Chang Won Lee, Pak-Shing Li, Xun-Chuan Liu, Yong Zhang, Zhiyuan Ren, Mika Juvela, Leonardo Bronfman, Yue-Fang Wu, Ken'ichi Tatematsu, Xi Chen, Di Li, Amelia Stutz, Siju Zhang, L. Viktor Toth, Qiu-Yi Luo, Feng-Wei Xu, Jinzeng Li, Rong Liu, Jianwen Zhou, Chao Zhang, Mengyao Tang, Chao Zhang, Tapas Baug, E. Mannfors, Eswaraiah Chakali, Somnath Dutta

Published 2021-11-03Version 1

We present new 3-mm continuum and molecular lines observations from the ATOMS survey towards the massive protostellar clump, MM1, located in the filamentary infrared dark cloud (IRDC), G034.43+00.24 (G34). The lines observed are the tracers of either dense gas (e.g. HCO+/H13CO+ J = 1-0) or outflows (e.g. CS J = 2-1). The most complete picture to date of seven cores in MM1 is revealed by dust continuum emission. These cores are found to be gravitationally bound, with virial parameter, $\alpha_{vir}<2$. At least four outflows are identified in MM1 with a total outflowing mass of $\sim 45 M_\odot$, and a total energy of $\sim 1\times 10^{47}$ erg, typical of outflows from a B0-type star. Evidence of hierarchical fragmentation, where turbulence dominates over thermal pressure, is observed at both the cloud and the clump scales. This could be linked to the scale-dependent, dynamical mass inflow/accretion on clump and core scales. We therefore suggest that the G34 cloud could be undergoing a dynamical mass inflow/accretion process linked to the multiscale fragmentation, which leads to the sequential formation of fragments of the initial cloud, clumps, and ultimately dense cores, the sites of star formation.