A first systematic study of [OIII] 88 μ m at z > 8 : two luminous oxygen lines and a powerful ionized outflow in the first 600 million years

We present deep ALMA Band 7 observations of the [ O I I I ] 88 μ m line and underlying dust continuum emission in four UV-bright, gravitationally lensed (magnification μ = 1.4 − 3.8 ), JWST-selected galaxies at z = 8.5 − 10.3 , with observed magnitudes − 22.5 ≲ M U V ≲ − 20.5 . [ O I I I ] is confidently detected in UNCOVER-10646 at z = 8.5080 ± 0.0011 ( 15 σ ) and DHZ1 at z = 9.3113 ± 0.0006 ( 6 σ ), with both being intrinsically luminous systems [ L [ O I I I ] = ( 1.1 − 1.6 ) × 10 9 L ⊙ ] that follow the local [ O I I I ] -SFR relation. [ O I I I ] 88 μ m remains undetected in the two z > 10 targets, including in the z = 10.07 X-ray AGN UHZ1, where we obtain a deep limit of L [ O