A Testable Cross–Correlation Between Late–Time ISW Anisotropies and Galaxy–Spin Asymmetry in a Geometric Saturation Framework

Recent observations increasingly allow direct comparison between the standard ΛCDM expansion model and alternative formulations in which late–time accelera- tion arises from causal saturation of a finite domain rather than from a cosmological constant. In the saturation framework, the expansion rate H(z) may closely match ΛCDMatzerothorder,but the time evolution of gravitational potentials(Φ ̇+Ψ ̇)differs, leading to distinct signatures in the Integrated Sachs–Wolfe (ISW) contribution to the cosmic microwave background (CMB). If this geometric evolution possesses directional dependence, the resulting ISW anisotropies could correlate with the large–scale anisotropies already reported in galaxy–spin handedness distributions. The alignment (or anti–alignment) of these two independent observables constitutes a falsifiable prediction that can discriminate between geometric–saturation and ΛCDM interpretations of cosmic acceleration.