The collective voice of Lyα emitters: Insights from stacked JWST spectroscopy

How Lyα photons escape from galaxies during the first billion years remains a central question to understanding early galaxy evolution and cosmic re-ionisation. While Lyα emitters (LAEs) are known to be metal poor and highly ionised, many high-z studies rely on spatially integrated measurements, leaving the internal connection between Lyα emission, chemical enrichment, and feedback largely unexplored. We present a spatially resolved stacking analysis of 287 LAEs at z>4 observed with JWST/NIRSpec prism spectroscopy. By constructing a two-dimensional stack from public surveys (CAPERS, CEERS, JADES, and RUBIES), we probed the average internal structure of typical LAEs (z_ ̊m median =5.5, M_ ̊m UV, median =-18.7, EW(łya)_̊m median = 61 Å) on sub-kiloparsec scales. We find a clear radial decoupling between resonant and non-resonant emission. While EW(̋beta) and other optical lines decline with radius, EW(Lyα) increases towards the outskirts, and the Lyα escape fraction rises from sim16% in the centre to gtrsim24% at larger radii. This behaviour suggests that resonant scattering redistributes Lyα photons into outer regions, where escape becomes more efficient. Optical diagnostics and T_e measurements in this work reveal low metallicities (12+łog(̊m O/H) )∼-0.4). The latter place typical LAEs among the growing population of nitrogen-enhanced high-redshift galaxies, pointing to rapid and possibly feedback-driven chemical enrichment. The inferred ionising photon production efficiency, łog(ξ_ high ionisation parameters, negligible dust attenuation, and systematically elevated N/O ratios (łog( ̊m N/O ̊m ion / -1 )≃ 25.1-25.2, together with the high Lyα escape fractions, suggests that these systems are efficient, though not extreme, contributors to the ionising photon budget. The comparison of the observed radial trends of ultraviolet β slope, EW(łya), łya escape fraction, and metallicity in our LAE stack with results from SPICE radiation-hydrodynamic simulations shows that bursty supernova feedback models naturally reproduce the observed data, linking the spatial redistribution of Lyα to stochastic star formation and feedback-driven gas flows. Our results demonstrate that Lyα emission, chemical enrichment, and feedback are tightly connected in typical z>4 LAEs and highlight the power of spatially resolved stacking with JWST to uncover the internal physical drivers of early galaxy evolution.