速度弥散在Kennicutt-Schmidt关系中的作用
The role of velocity dispersion in the Kennicutt-Schmidt relation
- University of Crete（克里特大学）
- Foundation for Research and Technology-Hellas（希腊研究与技术基金会）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
该研究利用多个巡天数据，探究分子气体速度弥散是否作为已解析Kennicutt-Schmidt关系的隐藏参数，发现部分星系中速度弥散与KS关系残差显著相关，且较高的速度弥散对应较低的恒星形成率面密度。
中文摘要 AI 辅助
已解析的Kennicutt-Schmidt（KS）关系是恒星形成星系在千秒差距尺度上恒星形成速率面密度（$\Sigma_\mathrm{SFR}$）与分子气体面密度（$\Sigma_\mathrm{mol}$）之间的幂律关系。尽管其形式看似简单，但它表现出显著的弥散，表明除气体面密度外，还有其他物理参数的影响。我们研究了分子气体速度弥散（$\Delta v$）是否作为近邻星系中已解析KS关系的隐藏参数。我们使用了来自ALMaQUEST、EDGE-CALIFA和PHANGS-ALMA巡天以及单个星系M51的观测数据，这些数据提供了$\Sigma_\mathrm{SFR}$、$\Sigma_\mathrm{mol}$和$\Delta v$的空间分辨测量。我们根据$\Delta v$梯度相对于最佳拟合KS线的方向将星系分为两组：一组中$\Delta v$梯度与KS线完全对齐（A组），因此不贡献弥散；另一组中$\Delta v$梯度具有垂直于该线的分量（B组），从而贡献弥散。对于每组，我们拟合KS关系并检查拟合残差（$Res$）对$\Delta v$的依赖性。在B组中，我们发现$Res$与$\Delta v$之间存在弱但统计显著的关联，且这一关联在所有巡天中一致。包含$\Delta v$的三维拟合得到$\Sigma_\mathrm{SFR} \propto \Sigma_\mathrm{mol}^{1.15} \Delta v^{-0.59}$。我们得出结论：存在一组恒星形成星系，其中速度弥散作为KS关系中的次级参数，在固定$\Sigma_\mathrm{mol}$时，较高的$\Delta v$对应较低的$\Sigma_\mathrm{SFR}$。我们未发现该组成员身份与所检查的其他性质之间存在明显关联。
英文摘要
The resolved Kennicutt-Schmidt (KS) relation is a power-law relation between the surface densities of the star formation rate ($Σ_\mathrm{SFR}$) and molecular gas ($Σ_\mathrm{mol}$) in star-forming galaxies on kiloparsec scales. Despite its apparent simplicity, it exhibits substantial scatter, suggesting the influence of additional physical parameters beyond gas surface density. We investigate whether molecular gas velocity dispersion ($Δv$) acts as a hidden parameter in the resolved KS relation in nearby galaxies. We use spatially resolved measurements of $Σ_\mathrm{SFR}$, $Σ_\mathrm{mol}$, and $Δv$ from the ALMaQUEST, EDGE-CALIFA, and PHANGS-ALMA surveys and from observations of the single galaxy M51. We identify two groups of galaxies based on the direction of the $Δv$ gradient with respect to the best-fit KS line: one in which the $Δv$ gradient is completely aligned with the KS line (group A) and thus does not contribute to the scatter, and one in which it has a component perpendicular to the line (group B) and contributes to the scatter. For each group, we fit the KS relation and examine the dependence of the residuals ($Res$) of the fit on $Δv$. In group B, we find a weak but statistically significant correlation between $Res$ and $Δv$, which is consistent across all surveys. A three-dimensional fit including $Δv$ yields $Σ_\mathrm{SFR} \propto Σ_\mathrm{mol}^{1.15} Δv^{-0.59}$. We conclude that there is a set of star-forming galaxies for which the velocity dispersion acts as a secondary parameter in the KS relation, with higher $Δv$ corresponding to lower $Σ_\mathrm{SFR}$ at fixed $Σ_\mathrm{mol}$. We find no obvious correlation between membership in this set and the other properties examined.
