Concentrating the Dark Matter in Galaxy Clusters through Tidal Stripping of Baryonically-Compressed Galactic Halos

Understand

Gravitational lensing observations of massive X-ray clusters imply a steep characteristic density profile marked by a central concentration of dark matter.

• The observed mass fraction within a projected radius of 150 kpc is twice that found in state-of-the-art dark matter simulations of the standard Lambda-CDM cosmology.
• A central baryon enhancement that could explain this discrepancy is not observed, leaving a major puzzle.
• We propose a solution based on the merger histories of clusters.