Abstract:

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. 

Bio: 

National Astronomical Observatories, Chinese Academy of Sciences
Principal Investigator, Cosmic Dark Matter and Dark Energy Group
Recipient of the CAS One Hundred Talents Fellow
National Distinguished Young Scholar
Research Directions: cosmology and particle astrophysics, including dark matter detection, dark energy model and detection, cosmic microwave background, large scale structure, formation of first generation of luminous objects and reionization