Patchy Neutral Gas and Weak Outflows in z>5 Galaxies Challenge Uniform Reionization Narratives

The SPURS JWST program delivers the first individual-galaxy rest-UV absorption spectra at z=5–9, revealing low-ionization covering fractions that span 0.2–0.9 and velocity centroids from +70 to –140 km s⁻¹. This heterogeneity, observed in only six luminous Abell-2744 targets, implies that the neutral ISM remains porous well into the reionization epoch, allowing ionizing photons to escape through channels that average surveys wash out. Half the sample shows low-ionization gas near systemic velocity rather than the bulk outflows ubiquitous at z<3, hinting that inefficient supernova entrainment or unresolved inflows dominate in the lowest-mass, highest-sSFR systems. Because the data are drawn from a single lensing cluster and target only UV-bright sources, the reported diversity may understate the true scatter across the full galaxy population. The work remains a 2026 arXiv preprint and has not yet undergone peer review. Complementary ALMA [C II] kinematics in similar-redshift lensed galaxies (Carniani et al. 2024) and stacked Lyman-α emitter spectra from the EIGER survey (Matthee et al. 2024) both show elevated velocity dispersions at low stellar mass, supporting the interpretation that cold-gas dynamics shift markedly below 10⁹ M⊙. These spectra therefore expose a metal-enriched but geometrically complex ISM whose covering fractions and multiphase outflows must be incorporated into next-generation reionization simulations rather than parameterized by single escape-fraction values.