论文标题
NGC 1068中致密分子气的空间分辨恒星形成关系
Spatially resolved star-formation relations of dense molecular gas in NGC 1068
论文作者
论文摘要
我们分析了动力环境对Seyfert 2 Galaxy NGC 1068的Starburst（SB）环中恒星形成（SF）关系的影响。我们使用ALMA对HCN和HCO+的1-0过渡的发射进行图像，分辨率为56 PC。我们还以〜100 pc的分辨率和CO（3-2）的分辨率及其基础连续体发射在〜40 pc时使用了CO（1-0）的辅助数据。这些观察结果使我们能够探测一系列分子气（n（h2）〜10 $^{3-5} cm^{ - 3} $）。 SF率（SFR）源自HST/NICMOS成像的PA $α$线排放。我们分析了SF关系如何根据孔径大小和分子气体示踪剂的选择而变化。与CO（1-0）相比，HCN和HCO+线的Kennicutt-Schmidt关系中的散射约为较低的两到三倍。相关性失去统计显着性低于关键空间规模$ \ $ \ $ 300-400 pc。密度分子气（SFEDENSE）的SF效率在平均值$ \ simeq0.01 $ myr $^{ - 1} $周围显示出散射的分布，这是HCN发光度（L'（hcn））的函数。 SF关系的替代处方，将SFEDENSE与参数B $ \equivς$密度/$σ^2 $链接到气体的界限，其中$σ$密度是密集的分子气表面密度和$σ$ $σ$ $σ$，速度分散，解决了与SFEDEDENSERSE的速度相关的速度。我们在SFEDENSE-B图中识别两个分支，这些分支与SB环中的两个动态环境相对应，这些分支是由它们靠近条形环接口区域所定义的。该区域对应于两个密度波谐振的穿越，在云云碰撞的速率增加将有利于增强分子气体的压缩。我们的结果表明，银河动力学在气体转化为恒星的效率中起着重要作用。
We analyse the influence of the dynamical environment on the star formation (SF) relations of the dense molecular gas in the starburst (SB) ring of the Seyfert 2 galaxy NGC 1068. We used ALMA to image the emission of the 1-0 transitions of HCN and HCO+ with a resolution of 56 pc. We also used ancillary data of CO(1-0) at a resolution of ~100 pc, and CO(3-2) and its underlying continuum emission at ~40 pc. These observations allow us to probe a range of molecular gas densities (n(H2)~10$^{3-5}cm^{-3}$). The SF rate (SFR) is derived from Pa$α$ line emission imaged by HST/NICMOS. We analysed how SF relations change depending on the choice of aperture sizes and molecular gas tracer. The scatter in the Kennicutt-Schmidt relation is about a factor of two to three lower for the HCN and HCO+ lines compared to CO(1-0) for a common aperture. Correlations lose statistical significance below a critical spatial scale $\approx$300-400 pc. The SF efficiency of the dense molecular gas (SFEdense) shows a scattered distribution as a function of the HCN luminosity (L'(HCN)) around a mean value of $\simeq0.01$Myr$^{-1}$. An alternative prescription for SF relations, linking the SFEdense and the boundedness of the gas measured by the parameter b$\equivΣ$dense/$σ^2$, where $Σ$dense is the dense molecular gas surface density and $σ$ the velocity dispersion, resolves the degeneracy associated with the SFEdense-L'(HCN) plot. We identify two branches in the SFEdense-b plot that correspond to two dynamical environments in the SB ring, which are defined by their proximity to the bar-ring interface region. This region corresponds to the crossing of two density wave resonances, where an increased rate of cloud-cloud collisions would favour an enhanced compression of molecular gas. Our results suggest that galactic dynamics plays a major role in the efficiency of the gas conversion into stars.
