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Strong emission from doubly ionized oxygen is a beacon for some of the most intensely star forming galaxies known. JWST enables the search for this beacon in the early universe with unprecedented sensitivity. In this work, we extend the study of faint OIII₅₀₀₈ selected galaxies by an order of magnitude in line luminosity. We use publicly available UNCOVER DR1 JWST/NIRCam and HST imaging data of the cluster lensing field, Abell 2744, to identify strong (rest-frame EW>500) OIII₅₀₀₈ emitters at z7 based on excess F410M flux. We find N=68 z7 OIII candidates, with a subset of N=33 that have deep HST coverage required to rule-out lower redshift interlopers (13. 68 arcmin² with F814W 5 depth >28 AB). Such strong emission lines can lead to very red colors that could be misinterpreted as evidence for old, massive stellar populations, but are shown to be due to emission lines where we have spectra. Using this deep HST sample and completeness simulations, which calculate the effective survey volume of the UNCOVER lensing field as a function of OIII luminosity, we derive a new OIII luminosity function (LF) extending to 41. 09<log₁₀ (L/erg\, s^-1) <42. 35 which is an order of magnitude deeper than previous z6 OIII LFs based on JWST slitless spectroscopy. This LF is well fit by a power law with a faint-end slope of =-2. 07^+0. 22-₀. ₂₃. There is little or no evolution between this LF and published OIII LFs at redshifts 3 z7, and no evidence of a turnover at faint luminosities. The sizes of these extreme OIII emitters are broadly similar to their low redshift counterparts, the green peas. The luminosity function of OIII emitters matches that of Lyman- at the bright end, suggesting that many of them should be Lyman- emitters.
Wold et al. (Fri,) studied this question.