CEERS Key Paper. VIII. Emission-line Ratios from NIRSpec and NIRCam Wide-Field Slitless Spectroscopy at z > 2
Papovich, Casey; Yang, Guang; Finkelstein, Steven L.; Barro, Guillermo; Pérez-González, Pablo G.; Arrabal Haro, Pablo; Bagley, Micaela B.; Bisigello, Laura; Cleri, Nikko J.; Dickinson, Mark; Ferguson, Henry C.; Fontana, Adriano; Grazian, Andrea; Grogin, Norman A.; Hathi, Nimish P.; Holwerda, Benne W.; Kartaltepe, Jeyhan S.; Kewley, Lisa J.; Kirkpatrick, Allison; Kocevski, Dale D.; Koekemoer, Anton M.; Lucas, Ray A.; Pentericci, Laura; Pirzkal, Nor; Ravindranath, Swara; Somerville, Rachel S.; Trump, Jonathan R.; Wilkins, Stephen M.; Yung, L. Y. Aaron; Jaskot, Anne E.; Jung, Intae; Hirschmann, Michaela; Lotz, Jennifer M.; Nicholls, David C.; Simons, Raymond C.; Backhaus, Bren E.; Kurczynski, Peter; Davis, Kelcey; Rose, Caitlin; Wessner, Jessica
United States, Switzerland, Australia, Italy, United Kingdom, Malta, Spain, Netherlands
Abstract
We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and the Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey to measure rest-frame optical emission-line ratios of 155 galaxies at z > 2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Hα, [O III]/Hβ, and [Ne III]/[O II] emission lines in terms of redshift by comparing to lower-redshift SDSS, CLEAR, and MOSDEF samples. We find a significant (>3σ) correlation between [O III]/Hβ with redshift, while [Ne III]/[O II] has a marginal (2σ) correlation with redshift. We compare [O III]/Hβ and [Ne III]/[O II] to stellar mass and Hβ SFR. We find that both emission-line ratios have a correlation with Hβ SFR and an anticorrelation with stellar mass across the redshifts 0 < z < 9. Comparison with MAPPINGS V models indicates that these trends are consistent with lower metallicity and higher ionization in low-mass and high-SFR galaxies. We additionally compare to IllustrisTNG predictions and find that they effectively describe the highest [O III]/Hβ ratios observed in our sample, without the need to invoke MAPPINGS models with significant shock ionization components.