Dynamics of Merging Galaxy Clusters: What Can Simulated Analogs Tell Us?
Abstract
Post-pericenter mergers of galaxy clusters may provide a unique window into the behavior of dark matter by acting as "dark matter colliders." Mergers may also play a role in the evolution of cluster member galaxies and other astrophysical processes such as cosmic ray acceleration. To quantify these connections, we need reliable estimates of the basic dynamics of each observed merger: the time since pericenter, the maximum relative speed of the merging subclusters, pericenter distance, the merger phase (outbound vs returning for second pericenter), and the viewing angle (which is critical for determining the 3-d velocity and separation today, given that we measure only line-of-sight velocities and projected separations). We describe a new technique: finding analog systems in cosmological n-body simulations and extracting these parameters from the simulation. This eliminates many of the approximations used in the classic "timing argument" approach for estimating these parameters: assuming purely radial trajectories, assuming a specific mass profile or even point masses, neglecting substructure and surrounding large-scale structure, etc. We find analogs for 10 observed systems and show that we can distinguish between old and young systems, fast and slow, outbound and returning.
- Publication:
-
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23346808W