N-enhancement in GN-z11: First evidence for supermassive stars nucleosynthesis in proto-globular clusters-like conditions at high redshift?

Unusually high N/O abundance ratios were recently reported for a very compact, intensively star-forming object GN-z11 at z  = 10.6 from JWST/NIRSpec observations. We present an empirical comparison with the C, N, and O abundance ratios in Galactic globular clusters (GCs) over a large metallicity ran...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2023-05, Vol.673, p.L7
Main Authors: Charbonnel, C., Schaerer, D., Prantzos, N., Ramírez-Galeano, L., Fragos, T., Kuruvanthodi, A., Marques-Chaves, R., Gieles, M.
Format: Article
Language:English
Subjects:
Physics
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Summary:Unusually high N/O abundance ratios were recently reported for a very compact, intensively star-forming object GN-z11 at z  = 10.6 from JWST/NIRSpec observations. We present an empirical comparison with the C, N, and O abundance ratios in Galactic globular clusters (GCs) over a large metallicity range. We show that hot hydrogen-burning nucleosynthesis within supermassive stars (SMS) formed through runaway collisions can consistently explain the observed abundances ratio in GN-z11 and in GCs. This suggests that a proto-globular cluster hosting a SMS could be at the origin of the strong N-enrichment in GN-z11. Our model predicts the behavior of N/O, C/O, and Ne/O ratios as a function of metallicity, which can be tested if high- z objects similar to GN-z11 are detected with JWST in the future. Further studies and statistics will help differentiate the proto-GC scenario from the Wolf-Rayet scenario that we quantify with a population synthesis model, and shed more light on this peculiar object.
ISSN:0004-6361
1432-0746
1432-0756
DOI:10.1051/0004-6361/202346410