Emission-line Ratios and Ionization Conditions of CEERS Star-forming Galaxies with JWST/NIRSpec

Abstract Galaxy emission-line fluxes can constrain star formation rates (SFRs) and interstellar medium (ISM) ionization. We investigate rest-frame optical emission lines of 71 star-forming galaxies (SFGs) at redshift 0.7 < z < 7 using JWST/NIRSpec measurements from the Cosmic Evolution Early Release Science survey. We use H α to measure SFR and utilize Hubble Space Telescope CANDELS stellar mass estimates to determine specific SFR (sSFR) and compare with the SFG main sequence (MS). We create [O iii ] λ 5008/H β versus [Ne iii ] λ 3870/[O ii ] λ 3728 line ratio diagrams. The line ratios appear to correlate with sSFR, and our results suggest that sSFR is the parameter that governs ionization conditions rather than SFR or a galaxy’s distance from the MS. These measurements reveal a rich diversity of ISM conditions and physical galaxy properties throughout cosmic time.