In a companion paper we derived H = Ṁ/M from Vaidya-FRW junction conditions, detecting a localized accretion enhancement at zc ≈ 0. 63 at 2. 9σ in combined supernova, BAO, and CMB data. Because the interior scale factor couples to the total horizon mass M (v), a scalar with no angular dependence, the framework requires this signal to be spatially isotropic. We test this prediction by splitting Pantheon+ supernovae into hemispheres aligned with three CMB anomaly axes and fitting independently. All inter-hemisphere tensions are below 0. 35σ. The signal is detected at 2. 6-2. 8σ in every hemisphere. The Gaussian clump parameters are 10-50× more stable across sky cuts than w₀wₐ, whose best-fit values fragment by Δwₐ = 0. 16-0. 36 between hemispheres. Both results, isotropy of the signal and fragmentation of smooth parameterizations, were predicted in 1.
Brandon Yates (Thu,) studied this question.