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

Bunker, AJ, Saxena, A, Cameron, AJ, Willott, CJ, Curtis-Lake, E, Jakobsen, P, Carniani, S, Smit, R, Maiolino, R, Witstok, J, Curti, M, D'eugenio, F, Jones, GC, Ferruit, P, Arribas, S, Charlot, S, Chevallard, J, Giardino, G, De Graaff, A, Looser, TJ et al (2023) JADES NIRSpec Spectroscopy of GN-z11: Lyman- α emission and possible enhanced nitrogen abundance in a z = 10.60 luminous galaxy. Astronomy and Astrophysics, 677. ISSN 0004-6361

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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.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	EDP Sciences
Date of acceptance:	16 May 2023
Date of first compliant Open Access:	11 December 2023
Date Deposited:	11 Dec 2023 17:07
Last Modified:	11 Dec 2023 17:15
DOI or ID number:	10.1051/0004-6361/202346159
URI:	https://ljmu-9.eprints-hosting.org/id/eprint/22083

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