银河系的随机磁场
The Random Magnetic Field of the Milky Way
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中文总结 AI 辅助
本研究利用普朗克卫星408 MHz同步辐射天空数据，限制银河系大尺度各向同性随机磁场，发现其为垂直紧凑盘，局部rms强度约4 μG、标度高度约1 kpc，该随机场使超高能宇宙射线角弥散较此前模型更小。
中文摘要 AI 辅助
我们利用普朗克卫星对408 MHz同步辐射天空的重建结果，对银河系磁场的大尺度各向同性随机分量进行了限制。我们的分析同时拟合了随机场结构、相干场与本地前景的同步辐射贡献，以及各向同性和偶极偏移。该分析的一个新要素是利用30 GHz处的过量偏振发射来建模本地前景，这使我们能够保留97%的天空，而无需将这些结构纳入银河系尺度的磁场特征中。在相干场模型、宇宙射线电子分布、天空掩模和场轮廓的各种变化下，我们一致发现，主导的随机场分量是一个垂直方向上紧凑的盘，其局部方均根强度约为4 μG，1/e标度高度约为1 kpc，比大多数先前模型中的随机场薄得多。银河系内区的环形增强改善了对数据的拟合，而我们未发现存在大尺度螺旋图案或厚随机场盘的证据。拟合还得到了强度单极子为4-7 K，我们讨论了其可能的起源。我们量化了推断出的随机场对超高能宇宙射线角弥散的影响：与先前模型相比，天空中值弥散角最多小1.7倍，在个别方向上最多小2.4倍。
英文摘要
We constrain the large-scale isotropic random component of the Galactic magnetic field using the Planck reconstruction of the 408 MHz synchrotron sky. Our analysis simultaneously fits the random-field structure, the synchrotron contributions of the coherent field and local foregrounds, and isotropic and dipolar offsets. A new element of the analysis is the use of excess polarized emission at 30 GHz to model local foregrounds, allowing us to retain 97% of the sky without absorbing these structures into Galaxy-wide features of the magnetic field. Across variations in the coherent-field model, cosmic-ray electron distribution, sky mask, and field profile, we consistently find that the dominant random-field component is a vertically compact disk with a local rms strength of about 4 $μ$G and a 1/e scale height of approximately 1 kpc, substantially thinner than in most previous models. An annular enhancement in the inner Galaxy improves the fit to the data, whereas we find no evidence for either a large-scale spiral pattern or a thick random-field disk. The fits also yield an intensity monopole of 4-7 K, whose possible origin we discuss. We quantify the implications of the inferred random field for the angular smearing of ultrahigh-energy cosmic rays. Compared with previous models, the sky-median smearing angle is smaller by up to a factor of 1.7, and by up to 2.4 in individual directions.
发表机构
- Norwegian University of Science and Technology（挪威科技大学）
- New York University（纽约大学）
机构由 AI 辅助整理，请以论文原文为准。
