Parkes HI对南部Milky Way后面星系的观测。II。Crux和Great Attractor区域（l ~ 289度至338度）
Parkes HI observations of galaxies behind the southern Milky Way. II. The Crux and Great Attractor regions (l ~ 289 degree to 338 degree)
摘要：
作为我们绘制南银河系后面星系大规模分布的计划的一部分，我们在Crux和Great Attractor（GA）区域的回避区（ZOA）观察到314个光学选择，部分模糊的星系。这些观测是用帕克斯64米射电望远镜进行的，以单像素指向模式进行，在400<v<10500 km/s的速度搜索范围内达到典型的均方根噪声水平2-6 mJy。总共探测到162个星系。这可以解释为在调查区域的GA过密度的突出，这导致了附近星系的相对较高的分数。这也可以从相当窄的速度分布（主要限于3000- 6000 km/s）中看出，并且在给定的灵敏度和速度范围内，明显偏离了均匀星系分布的预期。在纬度、前景消光或环境方面，探测和未探测之间没有发现系统差异，除了丰富的诺玛星系团的中心部分，几乎没有任何星系被探测到。对星系HI含量的详细研究揭示了Norma星系团核心（Abell半径约为0.4）的HI缺乏，类似于在后发座星系团中发现的。通过这种观测技术获得的红移导致了所谓的红移ZOA的大幅减少。当结合光学ZOA红移巡天数据分析新HI数据的大尺度结构时，这一点是显而易见的。低纬度的探测提供了进一步的证据，证明诺玛墙的延伸，跨越了ZOA，特别是它在银道面上方以稍高的红移向半人马座-十字座星系团弯曲，而不是向半人马座星系团直接延伸。
英文摘要：
As part of our programme to map the large-scale distribution of galaxies behind the southern Milky Way, we observed 314 optically-selected, partially-obscured galaxies in the Zone of Avoidance (ZOA) in the Crux and Great Attractor (GA) regions. The observations were conducted with the Parkes 64m radio telescope, in a single-pixel pointed mode, reaching an rms noise level of typically 2-6 mJy over the velocity search range of 400<v<10500km/s. A total of 162 galaxies were detected. This can be explained by the prominence of the GA overdensity in the survey regions, which leads to a relatively higher fraction of nearby galaxies. It is also evident from the quite narrow velocity distribution (largely confined to 3000-6000km/s) and deviates significantly from the expectation of a uniform galaxy distribution for the given sensitivity and velocity range. No systematic differences were found between detections and non-detections, in terms of latitude, foreground extinction, or environment, except for the very central part of the rich Norma cluster, where hardly any galaxies were detected. A detailed investigation of the HI content of the galaxies reveals strong HI deficiency at the core of the Norma cluster (within about a 0.4 Abell radius), similar to what has been found in the Coma cluster. The redshifts obtained by this observing technique result in a substantial reduction of the so-called redshift ZOA. This is obvious when analysing the large-scale structure of the new HI data in combination with data from optical ZOA redshift surveys. The lower latitude detections provide further evidence of the extension of the Norma Wall, across the ZOA, in particular its bending towards the Cen-Crux clusters above the Galactic plane at slightly higher redshift, rather than a straight continuation towards the Centaurus clusters.
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