Power-Law Post-Merger Decay in Gravitational Wave Signals: Evidence for Fractional Dynamics Across Three Gravitational Regimes

We analyze post-merger gravitational wave signals from 486 events in the GWOSC catalog, identifying 109 measurements meeting quality thresholds (SNR >= 4.0, valid merger identification). Comparing exponential decay (standard GR ringdown) against power-law decay predicted by an 11-field coupled PDE framework with fractional Laplacian exponent alpha = 6/5, we find the coupled PDE model preferred in 73/109 measurements (67.0%, binomial p = 9.16 x 10^-5). The preference strengthens with signal quality: win rates increase from 63% (SNR 4-6) to 89% (SNR > 10). Combined with 88/124 galactic rotation curve fits (p = 1.68 x 10^-6) and solar-system GR recovery (epsilon < 1.15 x 10^-4), Fisher combined significance across 233 independent measurements reaches 5.8 sigma with zero free parameters. All code and data included for full reproducibility.