We present observations of HCN 3-2 emissions towards 37 local galaxies using 10-m Submillimeter Telescope (SMT). HCN 3-2 emission is detected in 23 galaxies. The correlation of infrared luminosity (LIR) and the luminosity of HCN 3-2 line emission measured in our sample is fitted with a slope of 1.11 and correlation coefficient of 0.91, which follows the linear correlation found in other dense gas tracers in the literatures. Although molecular gas above a certain volume density threshold (i.e., $n_{\rm H_2}\geq$ 10$^4$ cm$^{-3}$) statistically gave similar relation with infrared luminosity, the large scatter of HCN 3-2/HCN1-0 ratios for galaxies with different LIR indicates that dense gas masses estimated from the line luminosities of only one transition of dense gas tracers should be treated with caution for individual galaxies.

中文翻译：

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HCN 3-2 对本地星系样本的调查

我们使用 10 米亚毫米望远镜 (SMT) 展示了对 37 个本地星系的 HCN 3-2 排放的观测结果。在 23 个星系中检测到 HCN 3-2 发射。在我们的样品中测得的红外光度 (LIR) 和 HCN 3-2 线发射光度的相关性符合 1.11 的斜率和 0.91 的相关系数，这遵循在文献中其他致密气体示踪剂中发现的线性相关性。尽管高于一定体积密度阈值（即 $n_{\rm H_2}\geq$ 10$^4$ cm$^{-3}$）的分子气体在统计上与红外光度具有相似的关系，但 HCN 3 的大散射具有不同 LIR 的星系的 -2/HCN1-0 比率表明，对于单个星系，应谨慎处理仅根据稠密气体示踪剂的一个跃迁的线光度估计的稠密气体质量。