标题： 高分辨率观测银河系中心的OH（1720 MHz）脉泽 显示英文标题

标题： High-resolution Observations of OH(1720 MHz) Masers Toward the Galactic Center

摘要： 高分辨率VLA观测结果报告了来自Sgr A东和核周围盘的1720 MHz OH脉泽辐射，其空间和光谱分辨率分别为$\approx$2\dasec 5$\times$1\dasec 3和0.27\kms 。这项后续观测研究聚焦于最近发现的若干此类OH脉泽特征及其在这些银河系中心源方向上检测到的强烈圆偏振脉泽线。OH的1720 MHz脉泽线来源于C型激波后的碰撞激发气体，是分子云与相关X射线发射的壳型超新星遗迹之间可能发生的相互作用过程的重要诊断工具。目前的观测结果确认了所观测到的斯托克斯$V$信号是由于塞曼分裂，并且OH脉泽受到朝向银河系中心的散射介质的角扩展。利用散射扩展脉泽斑点的位置角度的相关性，估计了朝向银河系中心的散射介质中磁场波动的尺度长度大于0.1-0.2 pc。此外，利用与Sgr A东相关的脉泽斑点的动力学特性，在这一扩展的射电结构和银河系中心之间设定了5 pc的位移。 显示英文摘要

摘要： High-resolution VLA observations of 1720 MHz OH maser emission from Sgr A East and the circumnuclear disk with spatial and spectral resolutions of $\approx$ 2\dasec5 $\times$ 1\dasec3 and 0.27 \kms are reported. This follow-up observational study focuses on the recent discovery of a number of such OH maser features and their intense circularly polarized maser lines detected toward these Galactic center sources. The 1720 MHz maser line of OH arises from collisionally excited gas behind a C-type shock and is an important diagnostic of the interaction process that may occur between molecular clouds and associated X-ray emitting shell-type supernova remnants. The present observations have confirmed that the observed Stokes $V$ signal is due to Zeeman splitting and that the OH masers are angularly broadened by the scattering medium toward the Galactic center. The scale length of the magnetic field fluctuations in the scattering medium toward the Galactic center is estimated to be greater than 0.1-0.2 pc using the correlation of the position angles of the scatter-broadened maser spots. In addition, the kinematics of the maser spots associated with Sgr A East are used to place a 5 pc displacement between this extended radio structure and the Galactic center.