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JADES NIRSpec Spectroscopy of GN-z11: Lyman- α emission and possible enhanced nitrogen abundance in a z = 10.60 luminous galaxy

2023; EDP Sciences; Volume: 677; Linguagem: Inglês

10.1051/0004-6361/202346159

1432-0746

Andrew J. Bunker, Aayush Saxena, Alex J. Cameron, Chris J. Willott, Emma Curtis-Lake, P. Jakobsen, Stefano Carniani, Renske Smit, R. Maiolino, Joris Witstok, Mirko Curti, Francesco D’Eugenio, Gareth C. Jones, Pierre Ferruit, S. Arribas, S. Charlot, Jacopo Chevallard, Giovanna Giardino, Anna de Graaff, Tobias J. Looser, Nora Lützgendorf, Michael V. Maseda, Tim Rawle, Hans‐Walter Rix, Bruno Rodríguez Del Pino, Stacey Alberts, Eiichi Egami, Daniel J. Eisenstein, Ryan Endsley, Kevin Hainline, Ryan Hausen, Benjamin D. Johnson, G. H. Rieke, Marcia Rieke, Brant Robertson, Irene Shivaei, Daniel P. Stark, Fengwu Sun, Sandro Tacchella, Mengtao Tang, Christina C. Williams, Christopher N. A. Willmer, William Baker, Stefi A. Baum, Rachana Bhatawdekar, R. A. A. Bowler, Kristan Boyett, Zuyi Chen, Chiara Circosta, Jakob M. Helton, Zhiyuan Ji, Nimisha Kumari, Jianwei Lyu, Erica J. Nelson, Eleonora Parlanti, Michele Perna, Lester Sandles, Jan Scholtz, Katherine A. Suess, Michael W. Topping, Hannah Übler, Imaan E. B. Wallace, Lily Whitler,

Astrophysical Phenomena and Observations

We present JADES JWST/NIRSpec spectroscopy of GN-z11, the most luminous candidate z > 10 Lyman break galaxy in the GOODS-North field with M UV = −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 ] λ 3727, [Ne III ] λ 3869, and C III ] λ 1909), we infer a high ionisation parameter (log U ∼ −2). We detect the rarely seen N IV ] λ 1486 and N III ] λ 1748 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 ] λ 1748 observed may imply an unusually high N / O abundance. Balmer emission lines (H γ , H δ ) 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.