Evidence for GN-z11 as a luminous galaxy at redshift 10.957

TL;DR

This paper confirms GN-z11 as the most distant galaxy known, at redshift 10.957, by detecting UV emission lines that support its high redshift and provides insights into early galaxy formation and ionized gas conditions.

Contribution

The study reports the probable detection of UV emission lines confirming GN-z11's redshift at 10.957, establishing it as the most distant galaxy observed to date.

Findings

Detection of UV emission lines consistent with z=10.957

Support for GN-z11 as the most distant galaxy

Indications of dense ionized gas and possible AGN activity

Abstract

GN-z11 was photometrically selected as a luminous star-forming galaxy candidate at redshift z > 10 based on Hubble Space Telescope (HST) imaging data. Follow-up HST near-infrared grism observations detected a continuum break that was explained as the Ly-alpha break corresponding to z = 11.09 (+0.08-0.12). However, its accurate redshift remained unclear. Here we report a probable detection of three ultraviolet (UV) emission lines from GN-z11, which can be interpreted as the [C III] 1907, C III] 1909 doublet and O III] 1666 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 UV lines likely 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 (AGN) 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 in the beginning of re-ionization.