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arXiv 2301.08041astro-ph.COastro-ph.GA
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利用 WMAP 和 Planck 对偏振同步辐射进行形态学分析

Morphological Analysis of the Polarized Synchrotron Emission with WMAP and Planck

F. A. Martire, A. J. Banday, E. Martínez-González, R. B. Barreiro

AI总结:

本文使用纤维查找算法分析 WMAP/Planck 偏振同步辐射图,识别纤维并表征其偏振与 E/B 形态,同时借助 Minkowski 工具检验弥散辐射的非高斯性和各向异性,提出匹配观测统计性质的数据驱动模拟模型。

摘要:

远离银道面的明亮偏振同步辐射主要源自纤维状结构。我们实现了一种纤维体查找算法,可在偏振强度图中检测明亮的细长结构。我们分析了分别由 WMAP 和 Planck 在 23 和 30 GHz 观测的天空。我们识别出 19 条纤维,其中 13 条此前已被观测到。对于每条纤维,我们研究偏振分数,发现其数值通常大于纤维之外、排除银道面的区域,并且有两条纤维达到约 30% 的分数。我们研究纤维的偏振谱指数,发现所得谱指数与以往针对更弥散区域的分析所得数值(约 -3.1)一致。将偏振信号分解为 E 族和 B 族后,我们发现大多数纤维在 P_E 中被检测到,而在 P_B 中未被检测到。随后,我们重点理解 23 GHz 同步辐射弥散区域的统计性质。利用 Minkowski 泛函和张量,我们分析偏振强度图的非高斯性和统计各向同性。对于对应于较暗辐射 80% 的天空覆盖率,并在小于 6 度(ℓ > 30)的尺度上,对高斯性和各向同性的偏离显著高于 3σ。偏离程度在更小尺度上降低;然而,在所分析的最小尺度(约 1.5°)上仍保持显著较高。当分析 60% 天空覆盖率时,我们发现偏离从不超过 3σ。最后,我们提出一个简单的数据驱动模型,用于生成同步偏振辐射的非高斯、各向异性模拟。对这些模拟进行拟合,以匹配数据图中最暗 80% 天空覆盖率的光谱和统计性质。

英文摘要:

The bright polarized synchrotron emission, away from the Galactic plane, originates mostly from filamentary structures. We implement a filament finder algorithm which allows the detection of bright elongated structures in polarized intensity maps. We analyse the sky at 23 and 30 GHz as observed respectively by WMAP and Planck. We identify 19 filaments, 13 of which have been previously observed. For each filament, we study the polarization fraction, finding values typically larger than for the areas outside the filaments, excluding the Galactic plane, and a fraction of about 30% is reached in two filaments. We study the polarization spectral indices of the filaments, and find a spectral index consistent with the values found in previous analysis (about -3.1) for more diffuse regions. Decomposing the polarization signals into the $E$ and $B$ families, we find that most of the filaments are detected in $P_E$, but not in $P_B$. We then focus on understanding the statistical properties of the diffuse regions of the synchrotron emission at 23 GHz. Using Minkowski functionals and tensors, we analyse the non-Gaussianity and statistical isotropy of the polarized intensity maps. For a sky coverage corresponding to 80% of the fainter emission, and on scales smaller than 6 degrees ($\ell > 30$), the deviations from Gaussianity and isotropy are significantly higher than 3$σ$. The level of deviation decreases for smaller scales, however, it remains significantly high for the lowest analised scale ($\sim 1.5^\circ$). When 60% sky coverage is analysed, we find that the deviations never exceed 3$σ$. Finally, we present a simple data-driven model to generate non-Gaussian and anisotropic simulations of the synchrotron polarized emission. The simulations are fitted in order to match the spectral and statistical properties of the faintest 80% sky coverage of the data maps.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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