ALMA High-resolution Spectral Survey of Thioformaldehyde (H2CS) toward Massive Protoclusters.

Investigating the temperature and density structures of gas in massive protoclusters is crucial for understanding the chemical properties therein. In this study, we present observations of the continuum and thioformaldehyde (H₂CS) lines at 345 GHz of 11 massive protoclusters using the Atacama Large Millimeter/submillimeter Array telescope. High spatial resolution and sensitivity observations have detected 145 continuum cores from the 11 sources. H₂CS line transitions are observed in 72 out of 145 cores, including line-rich cores, warm cores, and cold cores. The H₂ column densities of the 72 cores are estimated from the continuum emission, which are larger than the density threshold value for star formation, suggesting that H₂CS can be widely distributed in star-forming cores with different physical environments. The rotation temperature and column density of H₂CS are derived using the XCLASS software. The results show that the H₂CS abundances increase as temperature rises and higher gas temperatures are usually associated with higher H₂CS column densities. The abundances of H₂CS are positively correlated with its column density, suggesting that the H₂CS abundances are enhanced from cold cores, warm cores, and line-rich cores in star-forming regions. [ABSTRACT FROM AUTHOR]