论文标题
恒星形成速率密度质量关系的新参数化：包含气体密度梯度
A new parameterization of the star formation rate-dense gas mass relation: embracing gas density gradients
论文作者
论文摘要
众所周知的是，与从均匀密度的气体储层相比，分子云和团块内部的气体密度梯度提高了恒星的形成率。应在密集气体质量$ m_ {dg} $和恒星形成率$ sfr $ sfr $ sfr $ sfr $之间观察到这种效果，其陡峭的气体密度梯度产生更高的$ sfr/m_ {dg} $比率。本文的内容是两个方面。首先，我们基于Parmentier（2019）引入的放大因子的概念，以重新定义密集 - 气体关系（即$ M_ {DG} $和$ SFR $之间的关系）。 $ sfr/m_ {dg} $比率不仅取决于气体的平均自由下落时间及其（内在的）星星形成效率，而且还取决于气体密度剖面的对数斜率$ -P $以及集团中心恒定密度区域的相对程度。其次，我们表明，附近的分子云遵循新定义的密集 - 气体关系，前提是它们的致密气体质量是根据体积密度标准来定义的。我们还发现了银河系中央分子区（CMZ）的密集分子云的趋势相同，尽管与附近的云相比，这一趋势缩小了$ 10 $。讨论了$（p，sfr/m_ {dg}）$参数空间中附近和cmz云的各个基因座。
It is well-established that a gas density gradient inside molecular clouds and clumps raises their star formation rate compared to what they would experience from a gas reservoir of uniform density. This effect should be observed in the relation between dense-gas mass $M_{dg}$ and star formation rate $SFR$ of molecular clouds and clumps, with steeper gas density gradients yielding higher $SFR/M_{dg}$ ratios. The content of this paper is two-fold. Firstly, we build on the notion of magnification factor introduced by Parmentier (2019) to redefine the dense-gas relation (i.e. the relation between $M_{dg}$ and $SFR$). Not only does the $SFR/M_{dg}$ ratio depend on the mean free-fall time of the gas and on its (intrinsic) star formation efficiency per free-fall time, it also depends on the logarithmic slope $-p$ of the gas density profile and on the relative extent of the constant-density region at the clump center. Secondly, we show that nearby molecular clouds follow the newly-defined dense-gas relation, provided that their dense-gas mass is defined based on a volume density criterion. We also find the same trend for the dense molecular clouds of the Central Molecular Zone (CMZ) of the Galaxy, although this one is scaled down by a factor of $10$ compared to nearby clouds. The respective locii of both nearby and CMZ clouds in the $(p, SFR/M_{dg})$ parameter space is discussed.
