Observable tests of self-interacting dark matter in galaxy clusters: BCG wobbles in a constant density core

Understand

Models of Cold Dark Matter predict that the distribution of dark matter in galaxy clusters should be cuspy, centrally concentrated.

• Constant density cores would be strong evidence for beyond-CDM physics, such as Self-Interacting Dark Matter (SIDM).
• An observable consequence would be oscillations of the Brightest Cluster Galaxy (BCG) in otherwise relaxed galaxy clusters.
• Offset BCGs have indeed been observed - but only interpreted via a simplified, analytic model of oscillations.