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Harvard ADS: A spectroscopic analysis of the ionizing photon production efficiency in JADES and CEERS: implications for the ionizing photon budget

Paper abstract: We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (\xi_{\rm ion}) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3\sigma) spectroscopic detections of H\alpha and H\beta in order to constrain intrinsic H\alpha luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral-energy distribution modeling. We find a sample median log_{10}(\xi{\rm ion,0}/erg Hz^{-1}) = 25.29^{+0.29}_{-0.37}, assuming f_{\rm esc}=0 for the escape fraction of Lyman continuum emission. We find significant correlation between \xi_{\rm ion,0} and z, with 17 objects at z > 4.64 having median log_{10}(\xi_{\rm ion,0}/erg Hz^{-1}) = 25.38^{+0.38}){-0.38}, with those below having log_{10}(\xi_{\rm ion,0}/erg Hz^{-1}) = 25.24^{+0.30}_{-0.33}. We also find significant, positive correlations between \xi_{\rm ion,0} and LUV; W{\lambda}([O iii]); [O iii]{\lambda}5007/[O ii]{\lambda}{\lambda}3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between \xi_{\rm ion,0} and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to \xi_{\rm ion,0}, z, and MUV to an empirically-motivated model of reionization, and folding in f_{\rm esc} estimates from direct observations of the Lyman continuum at z ~ 3 from the Keck Lyman Continuum Spectroscopic survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ~ 5 - 7.