New constraints on stellar feedback through [ O iii ] emission: interpreting ALMA and JWST observations with SPICE simulations

ALMA and JWST detected emission lines from the interstellar medium of star-forming galaxies during the Epoch of Reionization, reaching redshifts up to z = 14. Among these, O iii lines offer a powerful diagnostic of metal enrichment, gas ionization, and the impact of stellar feedback in galaxies at z > 6. Modeling such emission in cosmological simulations is challenging due to the wide range of spatial scales and physical processes involved. To address this, we develop a post-processing pipeline that implements a sub-grid model for O iii line emission within the SPICE radiation-hydrodynamical simulations. The simulation explores three supernova feedback prescriptions-bursty-sn, smooth-sn, and the hypernova-based hyper-sn. We examine how these feedback modes affect metal enrichment, neutral gas fraction, size and morphology of the ionized halos traced by O iii emission in the optical and FIR rest frame. We find that O iii emission predominantly arises from gas that is both shock-heated and radiatively ionized. We further characterize the mass-metallicity relation and the correlation between neutral gas fraction and O iii luminosity. Bursty-sn efficiently ionizes gas but enriches galaxies less effectively by z = 5. This leads to fewer bright O iii emitters than in the smooth-sn model, with both bursty-sn and hyper-sn showing suppressed luminosity functions. Spatially resolved O iii emission shows that smooth-sn generally produces more compact galaxies and slightly higher V/σ values, though with overlap among models. Our results demonstrate that O iii emission is a sensitive tracer of stellar feedback at high redshift and highlight the need for observations reaching fainter luminosities where feedback effects are strongest.