Bridging Optical and Far-infrared Emission-line Diagrams of Galaxies from Local to the Epoch of Reionization: Characteristic High [O iii] 88 μm/SFR at z > 6

We present photoionization modeling of galaxy populations at $z\sim0$, $2$, and $> 6$ to bridge optical far-infrared (FIR) emission-line diagrams. collect galaxies with measurements and/or FIR ([O III] 88 $\mathrm{\mu m}$ [C II] 158 m}$) emission line fluxes plot them on the [O III]$\lambda5007/\mathrm{H\beta}$--[N II]$\lambda6585/\mathrm{H\alpha}$ (BPT) L([O III]88)/SFR--L([C II]158)/SFR diagrams, where SFR is star-formation rate III]88) L([C II]158) are luminosities. aim explain distributions two diagrams models that employ three nebular parameters: ionization parameter $U$, hydrogen density $n_\text{H}$, gaseous metallicity $Z_\text{gas}$. Our successfully reproduce parameters local galaxies, then predict The predicted illustrate redshift evolution all diagrams; e.g., III]$/\mathrm{H\beta}$ III]88/[C II]158 ratios continuously decrease from $z > $0$. Specifically, exhibit $\sim\!0.5$ dex higher $U$ than low-redshift a given $Z_\text{gas}$ show flat BPT diagram $\log{\mathrm{[O III]/H\beta}} = 0.5$-$0.8$. find some high III]88)/SFR ratios. To these ratios, our require low stellar-to-gaseous ratio or bursty/increasing history 6$. James Webb Space Telescope will test predictions scenarios for proposed by modeling.