AI 中文总结
研究黑洞自旋在视界尺度偏振测量中的特征，通过甚长基线干涉测量，区分不同机制产生的自旋偏振特征，经斯托克斯图像等进行推断，回顾相关诊断方法，指出当前观测对磁场等约束强于自旋，未来应优先考虑偏振诊断与互补系统学组合。
AI 中文摘要
黑洞的角动量通常用无量纲的“自旋”表示，它塑造强场时空并提供可与周围等离子体交换的旋转能量库。甚长基线干涉测量（VLBI）现已开始在事件视界尺度上分辨偏振发射。我们区分主要源于克尔时空中光子传播的自旋偏振特征与由穿过视界的电磁场和磁化等离子体动力学介导的特征。通过斯托克斯图像和紧凑的汇总统计数据，从VLBI相关性进行推断，以约束源并最终约束自旋。在此框架内，我们回顾了与视界正则性、磁场缠绕、磁捕获吸积、电磁能量提取、喷流基部和光圆柱结构以及视界和光子环偏振相关的诊断方法。当前事件视界望远镜的观测比约束自旋大小或方向更有力地约束了磁场几何形状、变异性、源方向、磁通量状态以及盘-喷流连接的各个方面。未来的观测和建模计划应优先考虑偏振诊断与互补系统学的组合，并测试在独立数据产品和合理的源模型中是否支持共同的自旋相关解释。
英文摘要
The angular momentum of a black hole, usually expressed in terms of a dimensionless "spin," both shapes the strong-field spacetime and provides a reservoir of rotational energy that can be exchanged with surrounding plasma. Very long baseline interferometry (VLBI) has now begun to resolve polarized emission on event-horizon scales. We distinguish polarimetric signatures of spin arising primarily from photon propagation in the Kerr spacetime from those mediated by horizon-threading electromagnetic fields and magnetized plasma dynamics. We trace the inference from VLBI correlations through Stokes images and compact summary statistics to constraints on the source and, ultimately, on spin. Within this framework, we review diagnostics linked to horizon regularity and magnetic-field winding, magnetically arrested accretion, electromagnetic energy extraction, jet-base and light-cylinder structure, and horizon and photon-ring polarization. Current Event Horizon Telescope observations constrain magnetic-field geometry, variability, source orientation, magnetic flux state, and aspects of the disk-jet connection more robustly than they constrain spin magnitude or sense. Future observing and modeling programs should prioritize combinations of polarimetric diagnostics with complementary systematics and test whether a common spin-dependent interpretation is supported across independent data products and plausible source models.
Comments33 pages, 8 figures. prepared for a Galaxies special issue on black hole spin
