演講資訊

摘要：

Galaxy clusters are the largest and rarest structures in our Universe. Approximately 80% of their mass content is dominated by dark matter which is invisible. This vast amount of dark matter makes galaxy cluster as an ideal laboratory to study the nature of dark matter. For the first part of this talk, I will show you an example of a combined strong + weak lensing and X-ray analysis of a galaxy cluster. After that, I will talk about our recent project, testing the collisionless nature of dark matter with radial acceleration relation (RAR). The RAR represents a tight correlation between the total and baryonic centripetal accelerations, from galaxy-scale to cluster-scale objects. This tight relation in the nonlinear regime provides a new insight to the nature of dark matter. We uses the BAHAMAS suites of cosmological hydrodynamical simulations to study the RARs in galaxy clusters for CDM and Self-Interacting Dark Matter (SIDM) models. Dark matter with self-interaction forms core structures in the cluster centres, which decreases the total radial acceleration and flatten the slope of their RARs in the high-acceleration region. This results in a significant difference between the RARs of the CDM and SIDM models. By comparing the RARs derived from different DM simulation runs with observational data from the CLASH program, we show that the cluster RAR can be used to place a stringent constraint on the SIDM cross section.