标题： Hinode宁静太阳观测中准各向同性磁场的证据 显示英文标题

标题： Evidence for Quasi-isotropic Magnetic Fields from Hinode Quiet Sun Observations

摘要： 一些最近利用Hinode太阳空间望远镜对630纳米的Fe I线中的塞曼效应的偏振光谱观测的研究得出结论，安静日冕的网间区域的磁场矢量强度处于hG范围，并且其倾角主要为水平方向。我们对这类观测的分析进行了批判性重新考虑，并进行了一次完整的贝叶斯分析，旨在尽可能从中提取信息，包括误差范围。我们应用了最近开发的BayesME代码，该代码对Milne-Eddington大气进行完整的贝叶斯推断。后验分布函数的采样是通过马尔可夫链蒙特卡罗方案获得的，并对边缘分布进行了详细分析。使用Kullback-Leibler散度来研究观测在推断过程中引入新信息的程度，从而得到足够约束的参数。我们的分析清楚地表明，只能推断出磁场强度的上限，而kG范围内的磁场完全被排除。此外，分析的Hinode观测中的噪声水平导致了对磁场方位角约束的信息显著损失。关于磁场的倾角，我们证明对于极化信号最大的像素，有一些信息可用于约束它。结果还指出，对于极化信号较小的像素，可以很好地用准各向同性分布来再现该场。 显示英文摘要

摘要： Some recent investigations of spectropolarimetric observations of the Zeeman effect in the Fe I lines at 630 nm carried out with the Hinode solar space telescope have concluded that the strength of the magnetic field vector in the internetwork regions of the quiet Sun is in the hG regime and that its inclination is predominantly horizontal. We critically reconsider the analysis of such observations and carry out a complete Bayesian analysis with the aim of extracting as much information as possible from them, including error bars. We apply the recently developed BayesME code that carries out a complete Bayesian inference for Milne-Eddington atmospheres. The sampling of the posterior distribution function is obtained with a Markov Chain Monte Carlo scheme and the marginal distributions are analyzed in detail. The Kullback-Leibler divergence is used to study the extent to which the observations introduce new information in the inference process resulting in sufficiently constrained parameters. Our analysis clearly shows that only upper limits to the magnetic field strength can be inferred with fields in the kG regime completely discarded. Furthermore, the noise level present in the analyzed Hinode observations induces a substantial loss of information for constraining the azimuth of the magnetic field. Concerning the inclination of the field, we demonstrate that some information is available to constrain it for those pixels with the largest polarimetric signal. The results also point out that the field in pixels with small polarimetric signals can be nicely reproduced in terms of a quasi-isotropic distribution.