# A SiO J = 5 - 4 Survey Toward Massive Star Formation Regions

## TL;DR

This survey of 199 massive star-forming regions using SiO J=5-4 line emission reveals diverse shock-related phenomena across different evolutionary stages, with no significant variation in SiO abundance or luminosity among these stages.

## Contribution

First large-scale SiO J=5-4 survey across multiple evolutionary stages of massive star formation regions, providing new insights into shock activities and chemical properties.

## Key findings

- SiO emission detected in 57% of sources, with varying detection rates across stages.
- Presence of both broad and narrow SiO lines indicating high-velocity and low-velocity shocks.
- No significant difference in SiO luminosity or abundance among different evolutionary stages.

## Abstract

We performed a survey in the SiO $J=5\rightarrow4$ line toward a sample of 199 Galactic massive star-forming regions at different evolutionary stages with the SMT 10 m and CSO 10.4 m telescopes. The sample consists of 44 infrared dark clouds (IRDCs), 86 protostellar candidates, and 69 young \HII\ regions. We detected SiO $J=5\rightarrow4$ line emission in 102 sources, with a detection rate of 57\%, 37\%, and 65\% for IRDCs, protostellar candidates, and young \HII\ regions, respectively. We find both broad line with Full Widths at Zero Power (FWZP) $>$ 20 \kms and narrow line emissons of SiO in objects at various evolutionary stages, likely associated with high-velocity shocks and low-velocity shocks, respectively. The SiO luminosities do not show apparent differences among various evolutionary stages in our sample. We find no correlation between the SiO abundance and the luminosity-to-mass ratio, indicating that the SiO abundance does not vary significantly in regions at different evolutionary stages of star formation.