Thermal SZ scaling relations between Y (integrated Compton parameter) and cluster mass deviate from self-similar ΛCDM predictions. The Y-M relation shows shallower slope and higher scatter than expected, with redshift-evolving normalization inconsistent with simple gravitational heating (Planck 2013; Battaglia 2012). Required feedback strengths to reconcile observations are difficult to fine-tune with star-formation + metallicity constraints.
The standard model has self-similar Y-M scaling from gravity-only cluster heating. Recovering observed shallower slope + higher scatter + evolving normalization demands either fine-tuned feedback or modified gas physics, neither of which is parsimonious within minimal ΛCDM.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the Y-M scaling deviations from self-similar come from cascade-thermalized initial conditions plus gravitational superposition. The cascade collision energy regime (P22, P23) deposits cluster-progenitor matter with born-hot thermodynamics (E_therm/E_vir ≈ 4.5 from Paper 4 Section 3.7); cluster mergers operate on this born-hot inherited population.
Plasma Equivalence Theorem (P29, P30) preserves the cascade-deposited thermodynamic state through cluster assembly, contributing to the Y-M relation deviations. Gravitational superposition (P50, P51, P52, P54) gives apparent dynamical mass M_eff = A × M_baryonic with cluster A ≈ 1.10 to 1.20 (Paper 6 A6); the apparent shallower Y-M slope reflects the calibrated A factor's mass-dependence. Per Paper 6, the tSZ-to-mass relation includes both the cascade-deposited thermodynamic baseline and the Φ_mesh-modified mass calibration.
Pre-existing matter (P25) gives cluster-baryon heterogeneity that adds Y-M scatter at fixed mass. Combined with the broader S₈ tension family (recid 2, 13) and the cluster-mass bias (recid 214), the same M6 framework accounts for tSZ scaling deviations as cascade-thermodynamic + coherent-mesh signatures rather than fine-tuned feedback.
If precision Athena + Lynx + Simons Observatory tSZ surveys find Y-M scaling fully consistent with self-similar ΛCDM + standard-feedback predictions at the 5% level (no cascade-mesh signature), the M6 explanation is refuted. The signature SCT prediction is the Y-M deviations matching the calibrated A factor + cascade-deposited thermodynamic state.