FOREST用野边山45米望远镜进行的无偏银道面成像巡天（FUGIN）V：银道面分子气体的稠密气体质量分数
FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45-m Telescope (FUGIN) V: Dense gas mass fraction of molecular gas in the Galactic plane
摘要：
最近对邻近星系分子云的观测表明，分子云中的致密气体具有恒星形成的准普适性质，对星系外星系的观测研究表明，恒星形成率（SFR）与分子气体表面密度之间存在星系尺度的相关性。为了全面理解这两种性质，重要的是量化分子云中稠密气体的质量分数f_DG。特别是，对于银河系（MW），有没有以前的研究解决了几个kpc的尺度上的f_DG盘。在这项研究中，f_DG测量超过5 kpc的MW的第一象限，根据CO J=1-0的数据，在l= 1 - 0 -50度获得的森林无偏银河平面成像调查的一部分，与野边山45米望远镜（FUGIN）项目。使用12 CO测量总分子质量，并且使用C18 O估计致密气体质量。包括f_DG在内的部分质量在银河系旋转切点距离的~30%范围内（例如，银河棒、远3 kpc臂、诺玛臂、盾牌臂、人马臂和臂间区域）。结果，对于整个目标区域获得了2.9^{+2.6}_{-2.6} %的平均f_DG。这个低数值表明，致密气体的形成是星系中恒星形成效率低下的主要因素。还发现f_DG随分子量盘结构的不同而有较大的变化。银河臂中的f_DG估计为~4- 5%，而在棒和臂间区域的f_DG小到~0.1- 0.4%。这些结果表明，致密气体的形成/破坏过程和它们的时间尺度是不同的MW的不同区域，导致SFR的差异。
英文摘要：
Recent observations of the nearby Galactic molecular clouds indicate that the dense gas in molecular clouds have quasi-universal properties on star formation, and observational studies of extra galaxies have shown a galactic-scale correlation between the star formation rate (SFR) and surface density of molecular gas. To reach a comprehensive understanding of both properties, it is important to quantify the fractional mass of the dense gas in molecular clouds f_DG. In particular, for the Milky Way (MW), there are no previous studies resolving the f_DG disk over a scale of several kpc. In this study, the f_DG was measured over 5kpc in the first quadrant of the MW, based on the CO J=1-0 data in l=10-50 deg obtained as part of the FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45-m Telescope (FUGIN) project. The total molecular mass was measured using 12CO, and the dense gas mass was estimated using C18O. The fractional masses including f_DG in the region within ~30% of the distances to the tangential points of the Galactic rotation (e.g., the Galactic Bar, Far-3kpc Arm, Norma Arm, Scutum Arm, Sagittarius Arm, and inter-arm regions) were measured. As a result, an averaged f_DG of 2.9^{+2.6}_{-2.6} % was obtained for the entirety of the target region. This low value suggests that dense gas formation is the primary factor of inefficient star formation in galaxies. It was also found that the f_DG shows large variations depending on the structures in the MW disk. The f_DG in the Galactic arms were estimated to be ~4-5%, while those in the bar and inter-arm regions were as small as ~0.1-0.4%. These results indicate that the formation/destruction processes of the dense gas and their timescales are different for different regions in the MW, leading to the differences in SFRs.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
