Bright beacons? ALMA non-detection of a supposedly bright [OI] 63-um line in a redshift-6 dusty galaxy

M. Rybak, L. Lemsom, A. Lundgren, J. Zavala, J. A. Hodge, C. de Breuck, C. M. Casey, R. Decarli, K. Torstensson, J. L. Wardlow, P. P. van der Werf

Published 2023-09-22Version 1

We report a non-detection of the [OI] 63-um 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. 2020); the new upper limit on the [OI] 63-um flux is almost 20-times lower. [OI] 63-um line could be a powerful tracer of neutral gas in the Epoch of Reionisation: yet our null result shows that detecting [OI] 63-um from z$\geq$6 galaxies is more challenging than previously hypothesised.