Thin dynamically cold stellar streams like GD-1 and Palomar 5 trace near-great-circle orbits in the Galactic halo with widths of tens of pc and very low velocity dispersion (Odenkirchen 2003; Grillmair & Dionatos 2006). They are exquisitely sensitive to the underlying potential and to perturbations by dark subhalos. ΛCDM expects rich subhalo populations to repeatedly disturb the streams, creating gaps, kinks, and thickening that observations sometimes constrain to be smaller than predicted (Yoon 2011; Bovy 2017).
The standard model has CDM substructure halos (subhalos) at all mass scales perturbing the stellar halo. The observed gap structure in GD-1 and Pal 5 is sometimes attributed to subhalo flybys, but the inferred subhalo abundance from gap statistics conflicts with cosmological-simulation predictions about subhalo mass spectra.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, no CDM subhalos exist in SCT (P50, P54). The gap structure in GD-1, Pal 5, and similar streams comes from cascade-debris fragment substructure (P22, P25, P31, P32) inherited at deposition rather than from late-time CDM-subhalo flybys.
Cascade-stream parent events deposited the streams' progenitor material with intrinsic substructure: not perfectly uniform debris but with density variations from cascade-stage geometry. The observed gaps reflect this inherited cascade-debris substructure plus Φ_mesh spatial variations (P50, P51, P52) from the Milky Way + Local Group cosmic-web mesh that perturbs stream-orbit dynamics. Sibling-pocket gravitational influence (P58, P59, P60) at multi-Mpc scales adds tidal perturbations that contribute to gap formation.
The same M6 framework that resolves the cluster-substructure GGSL excess, the A_lens = 1.18 lensing excess (recid 16, 30), and the Bullet-Cluster mass-offset (recid 220) accounts for the thin-stream gap structure. There is no need to invoke ad-hoc CDM subhalos to perturb fragile streams; the substructure is intrinsic to the cascade-debris deposition geometry plus mesh-induced orbital perturbations. Pre-existing matter (P25) gives the streams their stellar-population diversity.
If precision Gaia + LSST stream-density modeling demands a CDM-subhalo population at ΛCDM-predicted abundance to explain the gap statistics (no cascade-debris-substructure or mesh-perturbation signature), the M6 no-DM-particle explanation is refuted. The signature SCT prediction is gap structure traceable to cascade-debris substructure with no independent subhalo flyby signature.