Bright Beacons? ALMA Non-detection of a Supposedly Bright [O i] 63 μm Line in a Redshift-6 Dusty Galaxy

Abstract

Abstract We report a non-detection of the [O i] 63 μm emission line from the z = 6.03 galaxy G09.83808 using ALMA Band 9 observations, refuting the previously claimed detection with APEX by Rybak et al.; the new upper limit on the [O i] 63 μm flux is almost 20-times lower. [O i] 63 μm line could be a powerful tracer of neutral gas in the Epoch of Reionization: yet our null result shows that detecting [O i] 63 μm from z ≥ 6 galaxies is more challenging than previously hypothesized.