خطوط الانبعاث القوية [OIII]+Hβ كمصدر رئيسي للإشعاع المؤين في عصر إعادة التأين ✛ ✦

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2606.05323v1

We quantify the ionizing photon production at $$z\sim7$$ using the deepest spectroscopically confirmed sample of strong [OIII]$$+$$H$$\beta$$ emitters (rest-frame EW$$>740$$ A) in the Abell 2744 field. Leveraging ultra-deep UNCOVER F410M imaging ($$5\sigma\sim29$$ AB) and gravitational lensing, we probe an order of magnitude deeper than previous JWST WFSS [OIII] studies, reaching a luminosity limit of $$\log(L_{\rm{[OIII]}+\rm{H}\beta}/\text{erg s}^{-1})=41.3$$. Our rest-frame optical emission-line selection probes some of the youngest, metal- and dust-poor galaxies, identifying a large population of continuum-faint, ionizing candidates. NIRSpec follow-up of a luminosity-representative subset confirms $$72\%$$ of targets, providing detailed characterization of 18 emitters. Balmer decrements reveal negligible dust, while strong-line diagnostics indicate extremely low metallicities ($$12+\log(\text{O/H})=6.8\text{--}7.7$$). With typical [OII]/[OIII] ratios of $$0.054\pm0.007$$, we infer an average Lyman continuum escape fraction near the canonical $$f_{\text{esc}}=20\%$$. Correcting for the spectroscopic confirmation rate, we find that these high-EW emitters represent $$56\pm12\%$$ of the total UV-selected population by number density. Integrated to our survey limits, the ionizing budget of these emitters ($$\log(\dot{N}_{\rm ion}/{\rm s}^{-1}\,\text{Mpc}^{-3})=50.63\pm0.05$$) accounts for $$\sim70\%$$ of the total budget required for reionization at $$z\sim7$$. This result is consistent with empirical benchmarks. These results establish [OIII]$$+$$H$$\beta$$ selection as a powerful, dust-insensitive probe, showing that known galaxy populations significantly power reionization.