ΛCDM predicts a monotonic c-M relation where less massive halos are more concentrated. Observational data, particularly cluster-scale gravitational lensing, shows a flatter relation or significant outliers, with massive clusters exhibiting higher-than-expected concentrations (over-concentration problem) (Dutton & Macciò 2014; Meneghetti 2014). The discrepancy suggests either misunderstanding of halo assembly or non-gravitational physics modifying core structure.
The standard model has c ∝ M^(−0.1) from gravity-only structure formation in cuspy NFW halos. Recovering observed flat c-M relation with high-mass over-concentration demands either fine-tuned baryonic feedback or modifications to standard hierarchical assembly, neither of which is parsimonious.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the c-M relation scatter is the same cascade-stream + gravitational-superposition signature that produces halo concentration diversity (recid 192). The collision-seeded structure (P22, P25) deposits halos with diverse cascade-stream geometries, naturally producing a flatter c-M relation than the ΛCDM monotonic prediction.
Per Paper 13, A* = 5.970 in fully virialized halos is derived parameter-free from 1/f_b (P50, P51, P52, P54). Massive clusters sit closer to A* (full virialization) producing the higher-than-expected effective concentrations through enhanced Φ_mesh contribution at large radii. Lower-mass halos in less dense environments have reduced A factors that flatten the c-M relation relative to NFW expectations. Angular-momentum inheritance (P31, P32) gives additional diversity through J/J_circ ratio variations that modify internal halo dynamics.
Pre-existing matter (P25) provides baryonic-content scatter at fixed total mass that further modulates apparent concentration. The same M6 framework that resolves the rotation-curve diversity (recid 112), halo concentration diversity (recid 192), the SHMR (recid 115), and the broader no-DM-particle phenomenology accounts for the c-M relation. There is no need for over-concentration-specific feedback or modified hierarchical-assembly physics.
If precision Euclid + LSST + Roman cluster c-M surveys with environment stratification find c-M relation fully consistent with ΛCDM monotonic predictions at the 5% level (no environment-dependent A-factor signature), the M6 cascade-stream + environmental explanation is refuted. The signature SCT prediction is the c-M relation flattening with environment density consistent with the A* = 5.970 framework.