The HIPASS survey of the Galactic plane in radio recombination lines
The HIPASS survey of the Galactic plane in radio recombination lines
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DOI：
10.1093/mnras/stv751
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发表时间：
2014-11
影响因子：
4.8
通讯作者：
M. Alves;M. Calabretta;R. Davies;C. Dickinson;L. Staveley-Smith;R. Davis;Tianyue Chen;A. Barr-A.-Bar
中科院分区：
文献类型：
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作者：
M. Alves;M. Calabretta;R. Davies;C. Dickinson;L. Staveley-Smith;R. Davis;Tianyue Chen;A. Barr-A.-Bar
我们提出了一个来自Hi Parkes全天空巡天和相关的回避区巡天的银河平面射电平行线（RRL）巡天，它映射了l = 196-0-52的区域，|B|在1.4GHz和14.4arcmin分辨率下，6 5 μ m。我们结合联合收割机三个RRL，H168α，H167α，和H166α，得到完全采样的弥漫电离辐射图沿着内银道面。速度信息的分辨率为20 kms −1，使我们能够研究电离气体的空间分布，并将其与CO追踪的分子气体的空间分布进行比较。有没有明确的CO关联的HII复合物，这表明母分子云已被恒星反馈破坏的演化状态。在银河系这个区域的自由-自由辐射的第一个明确的测量是从线积分的RRL辐射导出的，假设电子温度梯度的银心半径为496± 100 Kkpc −1。根据热连续图，我们提取了一个目录的312个源，通量密度，大小和速度。我们报告的第一个RRL观测南电离叶在银河系中心。线的轮廓和速度表明，这个学位规模的结构是在旋转。我们还提出了在3千秒差距臂中弥漫电离气体的新证据。He线主要在Hii区域观测到，而C线也在离OB星更远的地方观测到。这些数据代表了第一次观察到的弥漫C RRLs在银河系平面的频率为1.4GHz。目前的调查是有价值的一系列应用，从研究银河系星星的形成率，电子密度分布，热电离和冷原子气体的性质，在银河系平面的热和非热发射的分离。数据可供下载。
We present a Radio Recombination Line (RRL) survey of the Galactic Plane from the Hi Parkes All-sky Survey and associated Zone of Avoidance survey, which mapped the region l = 196 ◦ – 0 ◦ – 52 ◦ and |b| 6 5 ◦ at 1.4GHz and 14.4arcmin resolution. We combine three RRLs, H168α, H167α, and H166α to derive fully sampled maps of the diffuse ionized emission along the inner Galactic plane. The velocity information, at a resolution of 20kms −1 , allows us to study the spatial distribution of the ionized gas and compare it with that of the molecular gas, as traced by CO. The longitudevelocity diagram shows that the RRL emission is mostly associated with CO gas from the molecular ring and is concentrated within the inner 30 ◦ of longitude. There are Hii complexes with no clear CO association, suggesting an evolved state where the parent molecular cloud has been disrupted by stellar feedback. The first unambiguous measure of the free-free emission in this region of the Galaxy is derived from the line-integrated RRL emission, assuming an electron temperature gradient with Galactocentric radius of 496±100Kkpc −1 . Based on the thermal continuum map we extracted a catalogue of 312 sources, with flux densities, sizes and velocities. We report the first RRL observations of the southern ionized lobe in the Galactic centre. The line profiles and velocities suggest that this degree-scale structure is in rotation. We also present new evidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are detected in this survey. The He line is mostly observed towards Hii regions, whereas the C line is also detected further away from the OB stars. These data represent the first observations of diffuse C RRLs in the Galactic plane at a frequency of 1.4GHz. The present survey is valuable for a range of applications, from studies of the Galactic star formation rate, electron density distribution, properties of the warm ionized and cold atomic gas, to the separation of thermal and non-thermal emission in the Galactic plane. The data are available for download.