南天二十厘米全天空偏振巡天（STAPS）的法拉第矩
Faraday moments of the Southern Twenty-centimeter All-sky Polarization Survey (STAPS)
AI总结：
本文基于南天二十厘米全天空偏振巡天（STAPS）计算法拉第矩，研究磁化星际介质特性，并与北天DRAO巡天对比，发现两者总体对应但偏振强度相差约1.8倍。
摘要：
宽带射电偏振巡天的法拉第层析成像使我们能够研究磁场及其与星际介质（ISM）的相互作用。此类巡天包括全球磁电离介质巡天（GMIMS），其覆盖北天和南天，频率范围约为300-1800 MHz。在本工作中，我们使用了GMIMS高频段南天数据（1328-1768 MHz），该巡天也被称为南天二十厘米全天空偏振巡天（STAPS），以18角分的分辨率观测南天。为了从STAPS中提取磁化星际介质的关键参数，我们计算了层析数据立方体的法拉第矩。这些矩包括总偏振强度、以偏振强度加权的平均法拉第深度、法拉第谱的加权弥散度及其偏度。我们将这些法拉第矩与北天相同频率范围内计算的结果（使用自治领射电天体物理天文台，DRAO）进行了比较，比较区域为一条与STAPS覆盖范围重叠的360度×30度条带。我们发现总偏振强度通常由弥散发射主导，该发射在银经l≤300度处减弱。法拉第矩揭示了多种偏振结构。高银纬处的低强度区域通常只有一个法拉第深度分量。由于其频率覆盖范围不够大，STAPS无法探测法拉第厚结构。将STAPS的法拉第深度与河外源的总旋转量进行比较表明，STAPS的频率足够高，以至于在中高银纬处，介入的星际介质会对背景发射造成去偏振。在重叠区域，STAPS和DRAO巡天表现出广泛的对应关系，但在偏振强度上相差约1.8倍。
英文摘要：
Faraday tomography of broadband radio polarization surveys enables us to study magnetic fields and their interaction with the interstellar medium (ISM). Such surveys include the Global Magneto-Ionic Medium Survey (GMIMS), which covers the northern and southern hemispheres at $\sim$ 300-1800 MHz. In this work, we used the GMIMS High Band South (1328-1768 MHz), also named the Southern Twenty-centimeter All-sky Polarization Survey (STAPS), which observes the southern sky at a resolution of 18$\arcmin$. To extract the key parameters of the magnetized ISM from STAPS, we computed the Faraday moments of the tomographic data cubes. These moments include the total polarized intensity, the mean Faraday depth weighted by the polarized intensity, the weighted dispersion of the Faraday spectrum, and its skewness. We compared the Faraday moments to those calculated over the same frequency range in the northern sky (using the Dominion Radio Astrophysical Observatory, DRAO), in a strip of $360\degr \times 30\degr$ that overlaps with STAPS coverage. We find that the total polarized intensity is generally dominated by diffuse emission that decreases at longitudes of $l \leq 300\degr$. The Faraday moments reveal a variety of polarization structures. Low-intensity regions at high latitudes usually have a single Faraday depth component. Due to its insufficiently large frequency coverage, STAPS cannot detect Faraday thick structures. Comparing the Faraday depths from STAPS to total rotation measures from extragalactic sources suggests that STAPS frequencies are high enough that the intervening ISM causes depolarization to background emission at intermediate and high Galactic latitudes. Where they overlap, the STAPS and DRAO surveys exhibit broad correspondence but differ in polarized intensity by a factor of $\sim$1.8.
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