The stochastic GW background (SGWB) is the random superposition of unresolved GW sources from compact binaries to possible primordial processes (Romano & Cornish 2017; Christensen 2019; Caprini & Figueroa 2018; Maggiore 2019). Predicting an SGWB satisfying tight bounds from CMB, BBN, PTAs, and ground-based interferometers while still allowing detectable signals in multiple bands requires careful balancing of astrophysical and primordial contributions.
The standard model partitions the SGWB into astrophysical (SMBH binaries, compact-object mergers) plus primordial (inflation, phase transitions, cosmic strings) contributions. Multi-band SGWB observations require careful tuning of source-population parameters across all source types to avoid overproducing any single component while accounting for the observed multi-frequency signal.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the stochastic GW background spectrum across all frequencies is a unified signature. Pre-existing SMBH binaries inherited from prior cascade cycles (P25, P28) dominate at low frequencies (nHz PTA band, recid 154). Mesh dissipation (P14, P15, P16) provides a secular tail extending across all frequencies through the continuous orbital-energy-extraction mechanism it imposes on every gravitationally bound system.
Cascade-seeded compact objects (P46) from the cascade-deposition epoch contribute at higher frequencies (mHz to kHz LISA + LIGO bands) through their inspiral and merger sequences. Constructive GW interference from comoving sources (P49) enhances the signal at all frequencies above the incoherent-sum prediction. The SGWB amplitude across frequencies emerges naturally from these cascade-related sources without requiring fine-tuned primordial contributions or anomalously high astrophysical merger rates.
The same M5 + M11 framework that resolves the megamaser-NanoGrav unified signal (recid 55), the SMBH-seed problem (recid 109), the final-parsec problem (recid 151), and the GWB at PTA frequencies (recid 154) accounts for the broader SGWB across all observable frequency bands. Each band samples a different cascade-seeded source population, and the multi-band signal coherence is the predicted SCT signature.
If precision PTA + LISA + LIGO + Cosmic Explorer multi-band SGWB observations find frequency dependence requiring exclusively standard astrophysical-binary populations at ΛCDM-predicted rates plus carefully tuned primordial new physics (no cascade-seeded continuous source population, no mesh-dissipation secular tail), the M5 + M11 unified-source explanation is refuted. The signature SCT prediction is the SGWB spectrum across all bands matching the cascade-seeded plus mesh-driven source population.