Modeling of HII regions and chemical evolution

High-redshift galaxies at \(z > 6\) have been observed by ALMA and JWST, with strong detections of [O III] 88 µm and 5007Å, respectively. To interpret the physical properties of such [O III] -bright galaxies, I develop a physical model of HII regions and applied it to hundreds of galaxy samples from zoom-in cosmological simulations, FirstLight (Ceverino+17).

Nakazato+23 show that bright [O III] emitters have ten-times higher ionized state than local galaxies and are already metal-enriched by ~ 0.2 \(Z_\odot\) even at \(z = 9\). Our estimation of mass-metallicity relation with rapid chemical enrichment is consistent with JWST observations (e.g., Nakajima+23). I propose line-ratio diagnostics for future synergies of JWST and ALMA. Measuring the flux ratios of rest-frame optical and far-IR lines allows us to estimate the physical conditions such as electron density and metallicity of the star-forming gas in high-redshift [O III] emitters (Fujimoto+24, Zavala+24).