标题： 银河系内ATLASGAL选择的巨分子云团块IV. 关联HII区的毫米氢再结合线 显示英文标题

标题： ATLASGAL-selected massive clumps in the inner Galaxy IV. Millimeter hydrogen recombination lines from associated HII regions

摘要： 毫米波段射电复合线（mm-RRLs）的观测被用来以一种与许多更传统的先前方法互补的方式寻找HII区。 我们进行了目标指向的mm-RRL观测（主量子数（$n$）为$\leq$至$\leq$的65条线，$\Delta n$分别为1、2、3和4，即）。 使用IRAM 30米和Mopra 22米望远镜观测了来自一个包含$\sim$10,000个ATLASGAL源目录的976个致密尘埃团块 (H$n\alpha$, H$n\beta$, H$n\gamma$和H$n\delta$)。 我们在 178 个团块中检测到了 H$n\alpha$ mm-RRL 发射；分别有 65、23 和 22 个团块检测到了 H$n\beta$、H$n\gamma$ 和 H$n\delta$。这是迄今为止发表的最大的毫米波激旋转跃线样本。 将这些团块的位置与射电连续谱巡天结果进行比较，我们确认了 134 个团块具有紧凑的射电对应源。其余 44 个团块的性质尚不清楚，但其中 8 个被认为可能是新的发射区。 在九个团块上观察到较宽的线宽（线宽 > 40 km s$^{-1}$），表明电离气体中存在显著的湍流运动。 我们发现，H NMATH$^{13}$CO NMATH$^{+}$（1 NMATH$-$0）发射线宽明显比没有毫米波激旋转跃线（mm-RRL）探测到的情况更宽。我们还发现毫米波激旋转跃线的积分流量与它们对应的射电源在6厘米连续谱流量密度之间存在相关性。我们发现毫米波激旋转跃线发射与 NMATH$n_{e}<10^{5}$厘米 NMATH$^{-3}$和半径大于0.03秒差距的电离氢区（HII区）有关。我们在178个团块中检测到了毫米波激旋转跃线，并识别出八个新的电离氢区候选者。来自九个团块的宽毫米波激旋转跃线可能表明它们起源于非常年轻的超紧致电离氢区。毫米波激旋转跃线追踪了高分辨率观测中探测到的射电连续谱源，其线参数显示出与嵌入式射电源及其母分子团块之间的关联。 显示英文摘要

摘要： Observations of millimeter wavelength radio recombination lines (mm-RRLs) are used to search for HII regions in an unbiased way that is complementary to many of the more traditional methods previously used. We carried out targeted mm-RRL observations (39$\leq$ principal quantum number ($n$) $\leq$65 and $\Delta n$ = 1, 2, 3 and 4, i.e. H$n\alpha$, H$n\beta$, H$n\gamma$ and H$n\delta$) using the IRAM 30m and Mopra 22m telescopes. We observed 976 compact dust clumps selected from a catalog of $\sim$10,000 ATLASGAL sources. We detected H$n\alpha$ mm-RRL emission toward 178 clumps; H$n\beta$, H$n\gamma$ and H$n\delta$ were also detected toward 65, 23, and 22 clumps, respectively. This is the largest sample of mm-RRLs detections published to date. Comparing the positions of these clumps with radio continuum surveys we identified compact radio counterparts for 134 clumps. The nature of the other 44 detections is unclear, but 8 detections are thought to be potentially new HII regions. Broad linewidths are seen toward nine clumps (linewidth > 40 km s$^{-1}$) revealing significant turbulent motions within the ionized gas. We find that the linewidth of the H$^{13}$CO$^{+}$ (1$-$0) emission is significantly wider than those without mm-RRL detection. We also find a correlation between the integrated fluxes of the mm-RRLs and the 6 cm continuum flux densities of their radio counterparts. We find that the mm-RRL emission is associated with HII regions with $n_{e}<10^{5}$ cm$^{-3}$ and HII region diameter >0.03 pc. We detected mm-RRLs toward 178 clumps and identified eight new HII region candidates. The broad mm-RRL from nine clumps may indicate that they arise in very young hyper-compact HII regions. The mm-RRLs trace the radio continuum sources detected by high-resolution observations and their line parameters show associations with the embedded radio sources and their parental molecular clumps.