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

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.

CLASSY VII Lyα Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-era Analogs*

“…To place the unexpected profile shapes, i.e., the double-peaked emission lines in DLA systems, in the broader context of the full diversity of observed Lyα profile shapes, requires high-resolution and high signal-to-noise ratio (S/N) UV spectroscopy of EoR analogs, including, but not limited to, Green Pea galaxies. The James Webb Space Telescope (JWST) observations reveal a diversity of galaxies in the EoR (e.g., Labbe et al 2023;Bunker et al 2023;Looser et al 2023;Saxena et al 2023;Tang et al 2023), spanning much wider ranges of galaxy properties than those of the local Green Peas.…”

The Puzzling Properties of the MACS1149-JD1 Galaxy at z = 9.11

“…It is worth noticing that another bright, pre-JWST high-z galaxy, GN-z11 (Oesch et al 2016), while extremely interesting (see, e.g., Bunker et al 2023;Cameron et al 2023a;Charbonnel et al 2023;Maiolino et al 2023;Tacchella et al 2023), is considered to possibly host an active galactic nucleus (AGN) and is at a redshift where [O III]λ5007 is beyond the NIRSpec sensitivity range and therefore makes it less likely for us to be able to carry out a direct metallicity measurement using the auroral lines. As such, JD1 is currently one of a few luminous galaxies at z > 9 that allow a reliable auroral line analysis.…”

Nitrogen-enriched, Highly Pressurized Nebular Clouds Surrounding a Super Star Cluster at Cosmic Noon

“…Using Cloudy photoionization calculations, Senchyna et al (2023) showcase a similarly high density n e  10 5 cm −3 for photoionized gas, and a high nebular N abundance ~log N O 0.25 ( ) at a gas metallicity of Z ≈ 0.1Z e . This object may be a high-redshift, high-mass (stellar mass ∼10 8 -10 9 M e Bunker et al 2023) version of the enrichment processes seen in Sunburst. Figure 11 shows the inferred LyC cluster nitrogen abundance compared to GN-z11, as well as to individual chemically anomalous stars in a local globular cluster, local star-forming galaxies, and local H II regions.…”

“…Shortly after the completion of this work, four pre-prints have appeared and have examined remarkably strong nitrogen emission lines seen in GN-z11, a z ≈ 11 galaxy confirmed through JADES NIRSpec IFU spectroscopy (Bunker et al 2023;Cameron et al 2023;Senchyna et al 2023;Charbonnel et al 2023). Using Cloudy photoionization calculations, Senchyna et al (2023) showcase a similarly high density n e  10 5 cm −3 for photoionized gas, and a high nebular N abundance ~log N O 0.25 ( ) at a gas metallicity of Z ≈ 0.1Z e .…”

“…Our measured abundance pattern falls on a diagonal line (which goes from upper left to lower right) that is traced by abundances measured from chemically anomalous dwarf stars in the Milky Way globular cluster NGC 6752, which indicates the various degree of mixing between N-enriched gas and chemically normal gas. Finally, we also compare to GN-z11, a z ∼ 11 galaxy hosting candidate globular cluster progenitors (Bunker et al 2023;Cameron et al 2023;Charbonnel et al 2023;Senchyna et al 2023).…”