Forward Generation of the GW150914 Gravitational-Wave Signal from a Constrained Propagation Model

This work tests whether a source–observer propagation relation calibrated independently from Pantheon+ Type Ia supernova data can forward-generate the GW150914 gravitational-wave (GW) chirp when applied unchanged in the gravitational-wave domain. By using leading-order chirp dynamics recovered as the GR 0PN limit of the UMH formulation, together with this fixed propagation relation, a strictly constrained forward waveform generator produces a waveform consistent with the observed inspiral–merger–ringdown morphology of GW150914, including chirp frequency evolution, merger timing, and a ringdown phase modeled as intrinsic relaxation dynamics. The generated signal is projected onto the LIGO detectors using standard antenna response functions and geometric time delays. A separate comparison with the publicly available strain data uses a single global time/polarity registration anchor and introduces no per-detector fitting, phase adjustment, frequency remapping, empirical amplitude fitting, waveform reparameterization, or higher-order tuning. This is not a template-fitting analysis, nor is it a competing replacement for General Relativity. In the present framing, the GR-order chirp law is recovered as the effective large-scale limit, while the specific objective of this paper is narrower: to test whether a propagation law fixed independently in cosmology remains self-consistent when applied to gravitational-wave observations. The propagation parameter governing the source–observer mapping is determined entirely from the Pantheon+ supernova dataset and is not recalibrated for the gravitational-wave signal, allowing GW150914 to serve as an independent cross-domain test. The forward model reproduces key features of the observed GW150914 morphology without event-specific waveform tuning, yielding network signal-to-noise ratio (SNR) ≳ 22 at the strongest detector-network consistency point of the coarse event-configuration sweep, under standard whitening and fixed-registration diagnostics. These results demonstrate that a gravitational-wave chirp can be forward-generated from an independently calibrated propagation law while preserving consistency across frequency evolution, phase accumulation, amplitude normalization, and ringdown relaxation.