The stellar-to-halo mass relation (SHMR) shows systematic features ΛCDM struggles to explain: peak star-formation efficiency at intermediate halo mass near 10¹² M☉, steep decline at both low and high mass, and overall low conversion efficiency of only 10 to 20% even in the most efficient halos (Behroozi 2013; Moster 2018). High-z JWST observations show galaxies with stellar masses inconsistent with their expected halo masses based on the standard relation.
The standard model assumes a single SHMR shape from feedback-regulated star formation in CDM halos. Recovering the observed peak shape and high-z deviations requires fine-tuned supernova feedback at low mass and AGN feedback at high mass, both of which require careful calibration to reproduce the observed efficiency curve.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the apparent halo mass M_halo,eff = A × M_baryonic comes from gravitational superposition (P50, P51, P52), with A ≈ 5.970 in fully virialized halos (parameter-free from 1/f_b in Paper 13). Different cosmic environments give different A factors: cluster-environment halos sit closer to A* (full virialization), while void-environment galaxies have reduced A from less coherent Φ_mesh contribution.
The SHMR shape emerges naturally from the M_baryonic-vs-M_halo,eff mapping under environment-dependent A. Collision-seeded structure (P22, P25) gives different baryonic content per cascade-stream parent: high-mass proto-galaxies inherit larger baryon reservoirs, low-mass proto-galaxies inherit smaller reservoirs. The peaked SHMR shape comes from the combination of A varying with environment and M_baryonic varying with cascade-stream history. There is no need for fine-tuned supernova or AGN feedback at the standard amplitudes.
Angular-momentum inheritance (P31, P32) affects star-formation efficiency through J/J_circ ratios that determine disk-vs-bulge geometry. In-cycle cascade-thermalized gas composition (P25, P28) gives additional scatter at fixed halo mass. The same M6 framework that produces the peak-statistics deficit (recid 71), the lensing amplitude excess (recid 16, 30), and the cluster GGSL excess accounts for the SHMR shape and scatter. There is no need for new dark-matter physics or modified halo-mass functions.
If precision Euclid + LSST + Roman SHMR surveys with environment stratification find the relation independent of host environment at the 1% level (no Φ_mesh A-factor signature), the M6 coherent-mesh SHMR explanation is refuted. The signature SCT prediction is the SHMR shape varying systematically with environment density and with cascade-stream J inheritance.