用22 GHz的5年WMAP极化测量约束规则银河磁场
Constraining the regular Galactic Magnetic Field with the 5-year WMAP polarization measurements at 22 GHz
摘要：
银河系磁场规则分量的知识提供了有关银河系结构和动力学的重要信息，也构成了确定宇宙射线轨迹的基本工具。它还可以提供清晰的窗口，在那里可以检测到原始磁场。我们希望获得银河系磁场分布的规则（大尺度）图案，该图案更好地拟合由WMAP在22 GHz的5年数据所看到的偏振同步辐射。我们系统地研究了一些银河系磁场模型：轴对称、双对称、对数旋臂、反转同心圆环和双环形。我们已经探索了使用基于网格的方法来定义这些模型中的每一个的参数空间。总共计算了100多万个模型。使用贝叶斯方法进行模型选择。对于每个模型，获得后验分布，并对不需要的参数进行边缘化，以获得边缘1-D概率分布函数。一般来说，轴对称模型提供了一个更好的描述晕组件，虽然参加他们的拟合优度，其余的模型不能被拒绝。在盘状组分的情况下，由于有效可用面积（小于整个图的8%和小于盘的40%），分析对于获得盘状大尺度结构不是非常敏感。然而，在一个给定的家庭的模型，最适合的参数是兼容的文献中发现的。更好地描述偏振同步加速器晕发射的模型族是轴对称模型，其磁螺旋臂的螺距角为~24度，并且在z ~ 1 kpc处具有1 microG的强垂直场。当拟合径向变化时，模型需要快速变化。
英文摘要：
[ABRIDGED] The knowledge of the regular component of the Galactic magnetic field gives important information about the structure and dynamics of the Milky Way, as well as constitutes a basic tool to determine cosmic rays trajectories. It can also provide clear windows where primordial magnetic fields could be detected. We want to obtain the regular (large scale) pattern of the magnetic field distribution of the Milky Way that better fits the polarized synchrotron emission as seen by the 5-year WMAP data at 22 GHz. We have done a systematic study of a number of Galactic magnetic field models: axisymmetric, bisymmetric, logarithmic spiral arms, concentric circular rings with reversals and bi-toroidal. We have explored the parameter space defining each of these models using a grid-based approach. In total, more than one million models are computed. The model selection is done using a Bayesian approach. For each model, the posterior distributions are obtained and marginalised over the unwanted parameters to obtain the marginal 1-D probability distribution functions. In general, axisymmetric models provide a better description of the halo component, although attending to their goodness-of-fit, the rest of the models cannot be rejected. In the case of disk component, the analysis is not very sensitive for obtaining the disk large scale structure, because of the effective available area (less than 8% of the whole map and less than 40% of the disk). Nevertheless, within a given family of models, the best-fit parameters are compatible with those found in the literature. The family of models that better describes the polarized synchrotron halo emission is the axisymmetric one, with magnetic spiral arms with a pitch angle of ~24 degrees, and a strong vertical field of 1 microG at z ~ 1 kpc. When a radial variation is fitted, models require fast variations.
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。
