JADES NIRSpec Spectroscopy of GN-z11: Lyman-α emission and possible enhanced nitrogen abundance in a z = 10.60 luminous galaxy
Chevallard, Jacopo; Maseda, Michael V.; Parlanti, Eleonora; Carniani, Stefano; Übler, Hannah; Circosta, Chiara; D'Eugenio, Francesco; Arribas, Santiago; Bunker, Andrew J.; Lützgendorf, Nora; Maiolino, Roberto; Perna, Michele; Willott, Chris J.; Cameron, Alex J.; Jones, Gareth C.; Kumari, Nimisha; Scholtz, Jan; Johnson, Benjamin D.; Ji, Zhiyuan; Shivaei, Irene; Nelson, Erica; Chen, Zuyi; Tang, Mengtao; Stark, Daniel P.; Endsley, Ryan; Rix, Hans-Walter; Lyu, Jianwei; Saxena, Aayush; Curtis-Lake, Emma; Jakobsen, Peter; Smit, Renske; Witstok, Joris; Curti, Mirko; Ferruit, Pierre; Charlot, Stephane; Giardino, Giovanna; de Graaff, Anna; Looser, Tobias J.; Rawle, Tim; Del Pino, Bruno Rodríguez; Alberts, Stacey; Egami, Eiichi; Eisenstein, Daniel J.; Hainline, Kevin; Hausen, Ryan; Rieke, George; Rieke, Marcia; Robertson, Brant E.; Sun, Fengwu; Tacchella, Sandro; Williams, Christina C.; Willmer, Christopher N. A.; Baker, William M.; Baum, Stefi; Bhatawdekar, Rachana; Bowler, Rebecca; Boyett, Kristan; Helton, Jakob M.; Sandles, Lester; Suess, Katherine A.; Topping, Michael W.; Wallace, Imaan E. B.; Whitler, Lily
United Kingdom, Canada, Denmark, Italy, Germany, Spain, France, Netherlands, United States, Australia
Abstract
We present JADES JWST/NIRSpec spectroscopy of GN-z11, the most luminous candidate z > 10 Lyman break galaxy in the GOODS-North field with MUV = −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 0.7 − 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 intergalactic medium expected at this early epoch), offset 555 km s−1 redwards of the systemic redshift. From our measurements of collisionally excited lines of both low and high ionisation (including [O II] λ3727, [Ne III] λ3869, and C III] λ1909), we infer a high ionisation parameter (log U ∼ −2). We detect the rarely seen N IV] λ1486 and N III] λ1748 lines in both our low and medium resolution spectra, with other high ionisation 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 photoionisation from an active galactic nucleus (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] λ1748 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 initial mass function) 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.