Thursday, May 11, 2017
As the most massive collapsed objects in the Universe, galaxy clusters are unique laboratories for exploring the nature of dark matter and studying the evolution of baryons. The thermodynamical state of the intra-cluster gas has been extensively studied through Chandra, Suzaku, and XMM-Newton X-ray observations. With the launch of Hitomi X-ray satellite, our ability to probe complex physical mechanisms has been greatly improved. Recently, stacking analysis of clusters has revealed an unidentified emission line at 3.5 keV. I will provide a comprehensive review on the line's potential interpretations including decaying dark matter as well as the detections and limits in the literature. I will also highlight the most recent Hitomi measurements on the evolution of chemical enrichment in clusters of galaxies.