HI surveys (ALFALFA) consistently detect more HI-massive galaxies than ΛCDM semi-analytic models predict, with M_HI > 10¹⁰ M☉ abundance exceeding model predictions (Haynes 2011; Maddox 2015). Standard models require efficient feedback to suppress massive halos but feedback overheats or expels gas, creating a deficit of high-HI-mass systems compared to observations. The tension implies a mechanism to maintain large cold gas reservoirs.
The standard model has gas accumulation in massive halos suppressed by AGN + supernova feedback (preventing high-HI-mass accumulation) plus shock-heating to virial temperatures. Recovering observed high-HI-mass abundance demands either weaker feedback (which conflicts with stellar-mass-function fits) or external gas-replenishment mechanisms.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, HI mass function high-mass excess comes from cascade-seeded gas reservoir + cosmic-web filament inheritance signature. Cascade-thermalized + in-cycle evolved gas reservoirs (P22, P25, P28) supply the substantial HI inventories that massive galaxies retain because the cascade-deposition process pre-loaded the gas budget without requiring late-time accretion.
Cosmic-web filament infrastructure (P34, P36) distributes the cascade-deposited gas reservoirs along filaments, with massive galaxies sitting at filament nodes maintaining their inherited HI through inflow from the surrounding cosmic-web context. Angular-momentum inheritance (P31, P32) gives the gas reservoirs J-aligned distribution patterns that protect them from feedback-driven outflow.
Gravitational superposition (P50, P51, P52) gives massive galaxies enhanced Φ_mesh contribution that holds the gas more effectively than particle-CDM models predict, allowing massive systems to maintain HI reservoirs against AGN + supernova feedback. Standard feedback proceeds at the same rates as ΛCDM, but the effective gravitational binding is stronger (A* = 5.970 in fully virialized halos, P52 parameter-free), so the gas is harder to expel. The same M11 framework that resolves the broader cascade-population phenomenology accounts for HI mass function high-mass excess as a cascade-seeded retention signature.
If precision SKA + ngVLA + future HI surveys find HI mass function fully consistent with ΛCDM feedback-regulated predictions at the 5% level (no cascade-seeded gas reservoir + cosmic-web inheritance signature), the M11 explanation is refuted. The signature SCT prediction is high-HI-mass abundance correlating with cosmic-web filament-node positions + cascade-stream J-aligned gas distributions.