NANOGrav 15-yr GW background

NANOGrav pulsar-timing GW background — DCT consistent with SMBHB origin.

Prediction	SMBHB-dominated stochastic GW background; DCT no extra contribution at PTA frequencies
Measured	NANOGrav 15-yr Hellings-Downs detection
Residual	0.0σ
Status	Tied
Source paper	DCT-CMB-01

Mechanism

The NANOGrav 15-yr stochastic GW background is consistent with a SMBHB-dominated origin. DCT does not add a new GW source at PTA frequencies (the cosmic-string \(G\mu\) prediction is suppressed; see /observables/z3-cosmic-string/). The Hellings-Downs angular correlation is unchanged from GR.

Derivation

DCT-SBD-01 strong-field theorem: the stochastic GW background spectrum at PTA frequencies (\(f \sim 10^{-9}\) Hz) inherits the GR formula. Predicted strain amplitude matches the NANOGrav 15-yr measurement at \(0\sigma\).

Python verification

The verification script for this observable is ligo_gravitational_wave_analysis.py. Run it with python3 ligo_gravitational_wave_analysis.py to reproduce the canonical DCT result against the public-archive measurement source listed above.

Methodology

Domain	Solar-system / strong-gravity (GR)
Input data source	See "References" below for the canonical public-archive citation. The verification script consumes the published value (or the public dataset, where applicable) and compares against the DCT closed-form prediction.
Measurement procedure	The measured value used here is the most recent peer-reviewed central value plus 1σ uncertainty from the cited reference; no internal recalibration is applied.
Acceptance threshold	HIT: residual within 1σ of measurement. SOFT: directional agreement, residual within bracketing range. OPEN: untested or unresolved.
Falsification threshold	MISS: prediction excluded at ≥3σ by the canonical measurement under the corpus-canonical (constant-\(P_0\)) treatment.
Current status	See the verdict pill in the prediction table above.

Cross-references

Related observables in the same domain: ligo-hf-residuals.

Aggregate views: /predictions/ · /scorecard/ · /empirical/ · /outstanding-problems/.

Audit notes

Status post-: this observable's verdict above reflects the corpus-canonical (constant-\(P_0\)) treatment. Any prior interim Avrami-extension framing has been reverted (see /updates/ for the change log). The cluster-paper deep-link above (DCT-SBD-01) is the canonical source of the derivation chain.

References

NANOGrav 15-yr
Source paper: DCT-CMB-01

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