慧眼对银心深度曝光的科学研究

Through analyzing data acquired through deep exposures of the Galactic Center region with HXMT, we plan to: (1) monitor known X-ray sources in this dense region and discover new X-ray transients; (2) systematically measure and study the properties of Fe K_alpha emission and cyclotron lines in X-ray binaries; (3) catch X-ray flares from Sgr A*; (4) study the relationship between diffuse X-ray emission and "Fermi Bubble"; and (5) look for the reported 3.5 keV line, which is sometimes attributed to the annihilation of dark matter particles. These studies will make full use of some of HXMT's unique design features, including the use of blind detectors (for background estimation), different field-of-views, good energy resolution of the low-energy instrument etc., combined with the scanning observing strategy (to cover a large region), to carry out some difficult but important studies (including the last three topics). Besides science results, we also expect to develop software for analyzing scanning data, transient detection algorithms, and also to improve instrument background estimation.

本项目计划通过分析慧眼卫星对银河系中心区域观测所获得的数据开展如下工作：（1）在这个源密度非常高的区域监测已知X射线源并发现新的暂现源；（2）系统测量和研究X射线双星谱里铁发射线和回旋吸收线的性质；（3）捕获Sgr A* 爆发事例；（4）研究大尺度弥漫辐射部分及与“Fermi Bubble”的关系；及（5）探索寻找有争议的3.5 keV（暗物质湮灭）谱线。这些工作将充分利用慧眼的组合视场、盲探测器、低能探测器优良的能谱分辨率等设计特点，并结合小天区扫描策略，开展一些难度比较高但非常重要的研究（包括后三个课题）。除了科学结果，团队还预期开发处理扫描数据的一些特殊软件、暂现源探测以及仪器本底的算法，为优化慧眼的科学产出做出贡献。

本项目充分利用“慧眼”卫星探测器的大面积、大视场、宽能段等特点，基于其对银河系及其它天区的观测数据，开展了以下几方面的研究工作：（1）寻找新的暂现源；（2）探测银道面弥漫辐射；3）验证3.5 keV谱线的真实性；（4）捕获Sgr A* 爆发事例；（5）研究宇宙X射线背景辐射。这些工作充分利用了慧眼的组合视场、盲探测器、低能探测器优良的能谱分辨率等设计特点，获得了银道面弥漫辐射天图及能谱，测量了宇宙X射线背景辐射的宽波段能谱，已完成两篇论文。除了科学成果，团队还开发了扫描数据处理软件及暂现源探测与仪器本底的算法，为优化慧眼的科学产出做出了贡献。