James Webb Space Telescope Feed Post

Harvard ADS: Genesis-Metallicity: Universal Non-Parametric Gas-Phase Metallicity Estimation

Paper abstract: We introduce genesis-metallicity, a gas-phase metallicity measurement python software employing the direct and strong-line methods depending on the available oxygen lines. The non-parametric strong-line estimator is calibrated based on a kernel density estimate in the 4-dimensional space of O2 = [O II]\lambda\lambda 3727,29/H\beta; O3 = [O III]\lambda 5007/H\beta; H\beta equivalent width EW(H\beta); and gas-phase metallicity 12 + \log(O/H). We use a calibration sample of 1551 galaxies at 0 < z < 10, with direct-method metallicity measurements compiled from the JWST/NIRSpec and ground-based observations. In particular, we report 145 new NIRSpec direct-method metallicity measurements at z > 1. We show that the O2, O3, and EW(H\beta) measurements are sufficient for a gas-phase metallicity estimate that is more accurate than 0.09 dex. Our calibration is universal, meaning that its accuracy does not depend on the target redshift. Furthermore, the direct-method module employs a non-parametric t_e(O II) electron temperature estimator based on a kernel density estimate in the 5-dimensional space of O2, O3, EW(H\beta), t_e(O II), and t_e(O III). This t_e(O II) estimator is calibrated based on 1001 spectra with [O III]\lambda 4363 and [O II]\lambda\lambda 7320,30 detections, notably reporting 30 new NIRSpec detections of the [O II]\lambda\lambda 7320,30 doublet. We make genesis-metallicity and its calibration data publicly available and commit to keeping both up-to-date in light of the incoming data.