Low-Dimensional Dust Attractors in Planck HFI 857 GHz: Phase-Space Evidence for a 1-2 Bias Floor in Primordial Non-Gaussianity

We demonstrate that Planck HFI 857 GHz dust foregrounds exhibit discrete low-dimensional attractors, revealing phase-space structure incompatible with Gaussian residual assumptions. We apply Phase-Mediated Attractor Dynamics (PMAD) to Planck HFI 857 GHz dust foreground maps. Using cosine-delta filtering, time-delay embedding, and stiffaxis projection, we find that local sky patches exhibit ∼9 effective phase-space dimensions with blockstructured recurrence plots, sharp basin transitions, and strong local contraction (negative angular Lyapunov proxies with sign-stability = 1.00). Global concatenation reduces the effective dimensionality to ∼3, revealing coherent low-dimensional structure across the full sky.