The axion was originally proposed to solve the theta-vacuum problem in QCD, it has been extensively studied as a candidate of the dark matter. I will briefly review the investigations on axion dark matter, then discuss a recently discovered phenomenon: the 3.5 keV line emission from certain galaxies and clusters. It has been proposed that this line is produced by dark matter decay into axions, which converted to photons in magnetic field. This hypothesis can be tested by measuring the polarization of the X-ray line photons.
陈学雷，国家天文台研究员，博士生导师。1999年哥伦比亚大学物理系博士毕业，先后在俄亥俄州立大学物理系、加州大学圣芭芭拉分校理论物理研究所等处工作，2004年底回国。入选中科院百人计划，获得国家杰出青年科学基金，现为国家天文台宇宙暗物质与暗能量研究团组首席科学家。主要从事宇宙学和粒子天体物理学的理论和数据分析研究，研究课题包括宇宙微波背景、宇宙大尺度结构、宇宙第一代发光天体的形成、再电离等，并领导了“天籁”21厘米中性氢巡天项目。
邀请人：张鹏杰 pjzhang@sjtu.edu.cn