The diffuse extragalactic gamma-ray background is the nearly isotropic high-energy glow remaining after resolved sources and Galactic foregrounds are subtracted. It arises from unresolved blazars, radio galaxies, star-forming galaxies, clusters, and possibly exotic processes (Fornasa & Sánchez-Conde 2015; Ackermann 2015; Inoue 2014; Di Mauro & Donato 2015). ΛCDM source models can reproduce much of the spectrum but face composition and anisotropy uncertainties, with known populations potentially insufficient at the highest energies.
The standard model partitions the diffuse gamma-ray background into known unresolved-source populations plus possible CDM annihilation/decay contributions. Reproducing both intensity and small-scale angular structure without overproducing any single population or invoking finely tuned dark-matter contributions remains challenging.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the diffuse extragalactic gamma-ray background residual comes from in-cycle cascade-seeded compact-object emission. Cascade-seeded SMBH (P46) inherited from prior cycles (P25, P28) populate the cosmic-web filament network throughout cosmic time, with their AGN activity producing residual gamma-ray emission across the high-energy band.
The cascade-seeded SMBH population is broader than standard hierarchical-formation models predict (recid 109), naturally producing the observed gamma-ray excess at the highest energies that known populations alone do not match. Gravitational superposition (P50, P51, P52) provides the cosmic-web context in which the cascade-seeded AGN population sits, with the Φ_mesh contribution holding the AGN host structure together. There is no need for exotic CDM annihilation or decay contributions; the residual is sourced by cascade-seeded compact objects.
The same M11 framework that resolves the metallicity floor (recid 125), the FRB diversity (recid 153), the JWST early-galaxy mass crisis (recid 7, 108), and the broader cascade-seeded compact-object phenomenology accounts for the diffuse gamma-ray background residual. The same cascade-seeded population produces multiple cross-correlated backgrounds (CIB, gamma-ray, X-ray, GW) at different wavelengths, providing multi-statistic cross-checks on the cascade-seeded source-population framework.
If precision CTA + ngVLA + Athena cross-correlation + composition measurements find the diffuse gamma-ray background fully consistent with standard known unresolved-source populations at the 5% level (no cascade-seeded SMBH residual contribution at high energies), the M11 cascade-seeded compact-object explanation is refuted. The signature SCT prediction is the gamma-ray residual matching the cascade-seeded AGN population predictions across cross-correlated multi-wavelength backgrounds.