观测宇宙学21厘米线的前景：II。3C 196和北天极周围磁场的韦斯特博克观测
Foregrounds for observations of the cosmological 21 cm line: II. Westerbork observations of the fields around 3C196 and the North Celestial Pole
摘要：
在未来的几年里，一个新的见解星系形成和宇宙的热历史，预计将来自高度红移宇宙学21厘米线的检测。宇宙学的21厘米线信号被埋在银河系和河外前景下，这些前景可能要亮几个数量级。用于有效地减去这些前景源的策略和技术需要在1-30弧分的相关角尺度上在强度和偏振方面详细了解它们的结构。我们目前的结果进行了观测与Westerbork望远镜在140-160 MHz的范围内，2弧分分辨率在两个领域位于中间银河系纬度，围绕明亮的类星体3C 196和北天极。观测它们的目的是为了确定可以对宇宙学21厘米线进行实际观测的天空区域的前景特性。利用旋转测度综合技术对偏振数据进行了分析。我们计算了总强度和偏振角功率谱。仔细校准总强度图，在3C 196场的情况下达到150000：1的高动态范围。[删节]
英文摘要：
In the coming years a new insight into galaxy formation and the thermal history of the Universe is expected to come from the detection of the highly redshifted cosmological 21 cm line. The cosmological 21 cm line signal is buried under Galactic and extragalactic foregrounds which are likely to be a few orders of magnitude brighter. Strategies and techniques for effective subtraction of these foreground sources require a detailed knowledge of their structure in both intensity and polarization on the relevant angular scales of 1-30 arcmin. We present results from observations conducted with the Westerbork telescope in the 140-160 MHz range with 2 arcmin resolution in two fields located at intermediate Galactic latitude, centred around the bright quasar 3C196 and the North Celestial Pole. They were observed with the purpose of characterizing the foreground properties in sky areas where actual observations of the cosmological 21 cm line could be carried out. The polarization data were analysed through the rotation measure synthesis technique. We have computed total intensity and polarization angular power spectra. Total intensity maps were carefully calibrated, reaching a high dynamic range, 150000:1 in the case of the 3C196 field. [abridged]
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