A survey of sulfur-bearing molecular lines toward the dense cores in eleven massive protoclusters

TL;DR

This study uses ALMA observations of 11 massive protoclusters to analyze sulfur-bearing molecules in dense cores, revealing their properties, distribution, and the effects of star-forming feedback on sulfur chemistry.

Contribution

It provides the first uniform large-sample analysis of sulfur-bearing molecules in dense cores across multiple protoclusters, enhancing understanding of sulfur chemistry and depletion.

Findings

SO is more widely detectable than ext{H}_2 ext{CS} in various environments.

ext{H}_2 ext{CS} and ext{TFSOT} trace different temperature regions.

Star-forming feedback increases sulfur molecule abundances and detection rates.

Abstract

Sulfur-bearing molecules are commonly detected in dense cores within star-forming regions, but the total sulfur budget is significantly low, when compared to the interstellar medium (ISM) value. The properties of sulfur-bearing molecules are not well understood due to the absence of large sample studies with uniform observational configurations. To deepen our understanding of this subject, we conducted a study using ALMA 870 \micron~observations of 11 massive protoclusters. By checking the spectra of 248 dense cores in 11 massive protoclusters, a total of 10 sulfur-bearing species (CS, SO, \htcs, NS, \sot, \ttso, \tfsot, \ttsot, \seoo, \octfs) were identified. The parameters including systemic velocities, line widths, gas temperatures, column densities, and abundances were derived. Our results indicate that SO appears to be more easily detected in a wider range of physical environments than \htcs, despite these two species show similarities in gas distributions and abundances. \tfsot~and \htcs~are good tracers of the temperature of sulfur-bearing species, in which \htcs~traces the outer warm envelope and \tfsot~is associated with high-temperature central-regions. High-mass star-forming feedback (outflow and other non-thermal motions) significantly elevates the sulfur-bearing molecular abundances and detection rates specifically for \sot~and SO. A positive correlation between the \sot~abundance increasing factor ($F$) and temperatures suggests that \sot~could serve as a sulfur reservoir on the grain mantles of dense cores and then can be desorbed from dust to gas phase as the temperature rises. This work shows the importance of a large and unbiased survey to understand the sulfur depletion in dense cores.