EHT Sgr A* shadow

Event Horizon Telescope shadow of Sgr A* — DCT inherits Kerr geometry.

Prediction	GR Kerr shadow for \(M = 4.15 \times 10^6 M_\odot\)
Measured	\(\theta_{\rm sh} = 51.8 \pm 2.3\,\mu\)as (EHT 2022)
Residual	0.57σ
Status	PASS
Source paper	DCT-PPN-01

Mechanism

DCT recovers GR exactly in the strong-field limit and reduces to the standard general-relativistic prediction. The 600-cell topology does not enter at strong-field; the no-scalar-hair theorem locks \(P = 1\) inside the horizon and leaves the GR observables invariant.

Derivation

Same horizon-locked \(P = 1\) argument as for M87* (DCT-SBD-01). The shadow diameter \(\theta_{\rm sh} = 51.8\,\mu\)as for the Sgr A* mass and distance, matching the EHT 2022 measurement at \(0.57\sigma\).

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: eht-m87.

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-PPN-01) is the canonical source of the derivation chain.

References

EHT M87* Paper VI
Source paper: DCT-PPN-01

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