January 2021 • 2021NatAs...5..256J
Abstract • GN-z11 was photometrically selected as a luminous star-forming galaxy candidate at redshift z > 10 on the basis of Hubble Space Telescope imaging data1. Follow-up Hubble Space Telescope near-infrared grism observations detected a continuum break that was explained as the Lyα break corresponding to z =11.0 9−0.12+0.08 ? (ref. 2). However, its accurate redshift remained unclear. Here we report a probable detection of three ultraviolet emission lines from GN-z11, which can be interpreted as the [C III] λ1907, C III] λ1909 doublet and O III] λ1666 at z = 10.957 ± 0.001 (when the Universe was only ~420 Myr old, or ~3% of its current age). This is consistent with the redshift of the previous grism observations, supporting GN-z11 as the most distant galaxy known to date. Its ultraviolet lines probably originate from dense ionized gas that is rarely seen at low redshifts, and its strong [C III] and C III] emission is partly due to an active galactic nucleus or enhanced carbon abundance. GN-z11 is luminous and young, yet moderately massive, implying a rapid build-up of stellar mass in the past. Future facilities will be able to find the progenitors of such galaxies at higher redshift and probe the cosmic epoch at the beginning of reionization.