报告题目：Axions and the 3.5 keV line
报 告 人：Xuelei Chen (NAOC,CAS)
报告摘要：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.