Pulsar Timing Arrays (NANOGrav, EPTA, PPTA) have detected a stochastic nanohertz gravitational-wave background at amplitude that requires more supermassive-black-hole-binary mergers than ΛCDM galaxy-merger histories naturally produce. The observed amplitude exceeds standard expectations from hierarchical-merger-driven SMBH binary populations, leaving room for either super-population astrophysical sources or exotic primordial contributions (NANOGrav 2023; Antoniadis 2023).
The standard model assumes the nanohertz GW background is sourced primarily by SMBH binaries formed during the cosmic history of galaxy mergers. The amplitude of the predicted signal is tied to the inferred SMBH-binary merger rate, which in turn depends on the hierarchical galaxy-merger history. When the observed background amplitude exceeds the merger-driven prediction, the standard model has nowhere obvious to place the excess without invoking new physics.
SCT replaces the imaginary hot-dense-center with a superluminal collision and the thermalized debris field that became our visible universe. The cascade of multi-stage thermalization that followed the collision left behind sparse leftover overdense regions that did not fully thermalize: the cascade-seeded compact-object population (paper 4208, P39 alt). These cascade-seeded SMBH precursors had initial masses of approximately 10³ to 10⁵ M☉ and provided a much higher abundance of SMBH seeds than ΛCDM's stellar-remnant-only seeding mechanism allows.
By the present epoch, this larger seed population has produced a larger SMBH binary population through subsequent gravitational dynamics, and that larger binary population produces a stronger nanohertz GW background. The PTA-detected amplitude is the direct signature of the cascade-seeded SMBH abundance: more SMBHs at all epochs, more binary inspirals at all redshifts, stronger integrated GW signal at nanohertz frequencies. The "excess" over ΛCDM hierarchical-merger predictions is exactly what M1 expects, because the cascade-seeded population vastly outnumbers what stellar-seed-only Eddington-limited growth would produce.
No exotic GW sources are needed. The cosmic-string scenarios, primordial-black-hole population scenarios, and new-physics phase-transition scenarios that ΛCDM has to invoke to fit the PTA amplitude are all unnecessary in SCT. The cascade-seeded SMBH binary population native to the SCT cosmogenesis framework is sufficient to produce the observed amplitude. The mechanism is the same one that explains the early SMBHs at z > 7 (r106), the JWST overmassive BHs at z ~ 10 (r109), and the early massive galaxies (r107 and r108). One single replacement (hot-dense-center to superluminal-collision) addresses all of these observations simultaneously without requiring any new physics beyond the cascade itself.
The PTA detection is therefore not a crisis for cosmology; it is a confirmation of the SCT cascade-seeded compact-object population that has been an explicit prediction of the framework since its initial development.
If the PTA-background SMBH-binary population is confirmed to be fully accounted for by hierarchical-merger SMBH binaries with stellar-seed origin (no statistical evidence for an additional cascade-seeded heavy-seed component), the M1 cascade-seeded compact-object explanation for the PTA amplitude is refuted. SKA-era PTA precision will provide the relevant statistical power within the next decade.