利用LoTSS和DRAGONS进行跨尺度的法拉第深度相似性研究
Faraday depth similarities across scales with LoTSS & DRAGONS
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中文总结 AI 辅助
该研究对比LoTSS和DRAGONS对银河系漫射同步辐射的观测，计算偏振强度与法拉第深度的一阶矩生成加权平均法拉第深度图，发现两调查结果在多方面有显著一致性，证明磁化ISM跨尺度耦合，差异处指向特殊ISM配置。
中文摘要 AI 辅助
银河系漫射同步辐射的法拉第旋转是复杂磁化星际介质（ISM）的有力追踪器，其结构跨越广泛的空间尺度，需要干涉测量和单天线宽带射电偏振观测来全面表征。我们比较了干涉测量的低频阵列两米天空调查（LoTSS；120 - 168 MHz）和单天线的多米尼克射电天体物理观测台北半球全球磁离子介质调查（DRAGONS；350 - 1030 MHz），它们在对空间和法拉第深度尺度的敏感性上具有互补性。我们计算了偏振强度与法拉第深度的一阶矩（M1），生成了两个调查共同区域的偏振强度加权平均法拉第深度图。这些图显示出尽管频率或空间尺度覆盖没有重叠，但两个调查之间仍有显著的一致性。在银河系北部区域，M1图在形态上相似，正负M1之间的边界只有小的空间偏移，且逐像素相关性强。在银河系南部区域，两个调查都追踪了之前在LoTSS中确定的法拉第深度随银河经度的梯度。超过一半像素的法拉第深度光谱显示出峰值数量和位置一致。通过计算结构函数证明的两个调查之间的强结构相似性，表明磁化ISM中存在跨空间尺度的耦合，使得干涉测量和单天线观测都能追踪相同的特征。差异实例指向了诸如去极化等观测效应占主导或由于局部物理条件导致这种耦合失效的ISM配置。
英文摘要
Faraday rotation of diffuse Galactic synchrotron emission is a powerful tracer of the complex, magnetised interstellar medium (ISM), whose structures span a wide range of spatial scales, requiring both interferometric and single-antenna broadband radio polarisation observations for full characterisation. We compare Faraday rotation in the interferometric LOw-Frequency ARray Two-Metre Sky Survey (LoTSS; 120-168 MHz) and the single-antenna Dominion Radio Astrophysical Observatory Global Magneto-Ionic Medium Survey of the Northern Sky (DRAGONS; 350-1030 MHz), which are complementary in their sensitivity to spatial and Faraday-depth scales. We calculate first moments (M1) of polarised intensity versus Faraday depth, producing polarised-intensity-weighted mean Faraday depth maps of the regions common to both surveys. These maps show remarkable agreement between the surveys despite the lack of overlap in frequency or spatial-scale coverage. In the northern Galactic region, the M1 maps are morphologically similar with only small spatial shifts in the boundaries between positive and negative M1, and strong pixel-by-pixel correlation. In the southern Galactic region, both surveys trace the Faraday-depth gradient with Galactic longitude previously identified in LoTSS. Faraday depth spectra show consistent numbers and locations of peaks for more than half of the pixels. The strong structural similarity between the surveys, demonstrated by computing structure functions, suggests coupling across spatial scales in the magnetised ISM, enabling both interferometric and single-antenna observations to trace the same features. Instances of differences point to ISM configurations where observational effects such as depolarisation dominate or where this coupling breaks down due to local physical conditions.
