We present JADES JWST/NIRSpec spectroscopy of GN-z11, the most luminous candidate z>10 Lyman break galaxy in the GOODS-North field with Mₔₕ=-21. 5. We derive a redshift of z=10. 603 (lower than previous determinations) based on multiple emission lines in our low and medium resolution spectra over 0. 8-5. 3 μm. We significantly detect the continuum and measure a blue rest-UV spectral slope of β=-2. 4. Remarkably, we see spatially-extended Lyman-α in emission (despite the highly-neutral IGM expected at this early epoch), offset 555 km s^-1 redward of the systemic redshift. From our measurements of collisionally-excited lines of both low- and high-ionization (including O II3727, Ne IIIλ3869 and C III]1909) we infer a high ionization parameter (U -2). We detect the rarely-seen N IV]1486 and N III]1748 lines in both our low and medium resolution spectra, with other high ionization lines seen in the low resolution spectrum such as He II (blended with O III]) and C IV (with a possible P-Cygni profile). Based on the observed rest-UV line ratios, we cannot conclusively rule out photoionization from AGN, although the high C III]/He II and N III]/He II ratios are compatible with a star-formation explanation. If the observed emission lines are powered by star formation, then the strong N III]1748 observed may imply an unusually high N/O abundance. Balmer emission lines (Hγ, Hδ) are also detected, and if powered by star formation rather than an AGN we infer a star formation rate of 20-30 M_ yr^-1 (depending on the IMF) and low dust attenuation. Our NIRSpec spectroscopy confirms that GN-z11 is a remarkable galaxy with extreme properties seen 430 Myr after the Big Bang.
Bunker et al. (Tue,) studied this question.