Issue |
A&A
Volume 687, July 2024
|
|
---|---|---|
Article Number | L11 | |
Number of page(s) | 6 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202450721 | |
Published online | 05 July 2024 |
Letter to the Editor
Discovery of a new N-emitter in the epoch of reionization
1
Observatoire de Genève, Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland
e-mail: daniel.schaerer@unige.ch
2
CNRS, IRAP, 14 Avenue E. Belin, 31400 Toulouse, France
Received:
14
May
2024
Accepted:
17
June
2024
We report the discovery of a compact star-forming galaxy at z = 9.380 in the GOODS-North field (named GN-z9p4), which shows numerous strong UV-optical emission lines and a single UV line, N IV] λ1486. This makes GN-z9p4 the third-highest redshift N-emitter known to date. We determined the nebular abundances of H, C, N, O and Ne, along with the size and other physical properties of this object, then compared them to those of the other N-emitters known so far and to other star-forming galaxies. Using the direct method, we found a metallicity of 12 + log(O/H) = 7.37 ± 0.15, which stands as one of the lowest among N-emitters. The N/O abundance ratio is highly super-solar, while C/O and Ne/O are normal compared to other galaxies at low metallicity. We show that the compactness of GN-z9p4 (with an effective radius of 118 ± 16 pc at 2 μm) and other N-emitters translates to very high stellar mass and star formation rate (SFR) surface densities, which could serve as a criterium for identifying other N-emitters. Future studies and larger samples are needed to understand these rare, and enigmatic objects that have only recently been discovered.
Key words: galaxies: high-redshift / galaxies: ISM / dark ages / reionization / first stars
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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