Tracing nitrogen enrichment across cosmic time with JWST
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arXiv
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| Auteurs principaux: | , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Cataldi, E. Belfiore, F. Curti, M. Moreschini, B. Marconi, A. Maiolino, R. Feltre, A. Ginolfi, M. Mannucci, F. Cresci, G. Ji, X. Amiri, A. Arnaboldi, M. Bertola, E. Bracci, C. Ceci, M. Chakraborty, A. Cullen, F. D'Amato, Q. Kobayashi, C. Lamperti, I. Marconcini, C. Scialpi, M. Ulivi, L. Zanchettin, M. V. |
| author_facet | Cataldi, E. Belfiore, F. Curti, M. Moreschini, B. Marconi, A. Maiolino, R. Feltre, A. Ginolfi, M. Mannucci, F. Cresci, G. Ji, X. Amiri, A. Arnaboldi, M. Bertola, E. Bracci, C. Ceci, M. Chakraborty, A. Cullen, F. D'Amato, Q. Kobayashi, C. Lamperti, I. Marconcini, C. Scialpi, M. Ulivi, L. Zanchettin, M. V. |
| contents | We present a comprehensive analysis of the nitrogen-to-oxygen (N/O) abundance ratio in a sample of ~ 660 star-forming galaxies at redshift z ~ 1-6, with a median redshift of z = 3.0, using deep JWST/NIRSpec spectroscopy. Leveraging detections of faint auroral emission lines in 92 galaxies at z>1 from both the MARTA survey and a large compilation of high-redshift literature objects, we derive direct electron temperature-based abundances for nitrogen and oxygen using rest-frame optical lines. We establish the first high-redshift calibrations of strong-line N/O diagnostics based on 'direct' abundance measurements, finding a mild evolution for the N2O2 = log([NII]6585/[OII]3727,3729) diagnostic and no clear evolution for the N2S2 = log([NII]6585/[SII]6717,6731) diagnostic compared to local realisations. We then investigate the N/O-O/H relation across cosmic time using both 'direct' abundances and strong-lines based measurements (additional 535 galaxies). We find evidence for mild but systematic nitrogen enhancement at high redshift: galaxies at z>1 exhibit N/O ratios elevated by ~0.18 dex (median offset) at fixed O/H compared to local trends, with a more pronounced enhancement at low metallicity (i.e. 12 + log(O/H) < 8.1), where the offset reaches up to ~0.4-0.5 dex. We consider several scenarios to explain the observed trends, including bursty star formation, differential metal loading, and inflows of pristine gas. Our results provide the most extensive confirmation of elevated N/O ratios at high-redshift to date based on rest-optical diagnostics and within a self-consistent frame. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_07955 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Tracing nitrogen enrichment across cosmic time with JWST Cataldi, E. Belfiore, F. Curti, M. Moreschini, B. Marconi, A. Maiolino, R. Feltre, A. Ginolfi, M. Mannucci, F. Cresci, G. Ji, X. Amiri, A. Arnaboldi, M. Bertola, E. Bracci, C. Ceci, M. Chakraborty, A. Cullen, F. D'Amato, Q. Kobayashi, C. Lamperti, I. Marconcini, C. Scialpi, M. Ulivi, L. Zanchettin, M. V. Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics We present a comprehensive analysis of the nitrogen-to-oxygen (N/O) abundance ratio in a sample of ~ 660 star-forming galaxies at redshift z ~ 1-6, with a median redshift of z = 3.0, using deep JWST/NIRSpec spectroscopy. Leveraging detections of faint auroral emission lines in 92 galaxies at z>1 from both the MARTA survey and a large compilation of high-redshift literature objects, we derive direct electron temperature-based abundances for nitrogen and oxygen using rest-frame optical lines. We establish the first high-redshift calibrations of strong-line N/O diagnostics based on 'direct' abundance measurements, finding a mild evolution for the N2O2 = log([NII]6585/[OII]3727,3729) diagnostic and no clear evolution for the N2S2 = log([NII]6585/[SII]6717,6731) diagnostic compared to local realisations. We then investigate the N/O-O/H relation across cosmic time using both 'direct' abundances and strong-lines based measurements (additional 535 galaxies). We find evidence for mild but systematic nitrogen enhancement at high redshift: galaxies at z>1 exhibit N/O ratios elevated by ~0.18 dex (median offset) at fixed O/H compared to local trends, with a more pronounced enhancement at low metallicity (i.e. 12 + log(O/H) < 8.1), where the offset reaches up to ~0.4-0.5 dex. We consider several scenarios to explain the observed trends, including bursty star formation, differential metal loading, and inflows of pristine gas. Our results provide the most extensive confirmation of elevated N/O ratios at high-redshift to date based on rest-optical diagnostics and within a self-consistent frame. |
| title | Tracing nitrogen enrichment across cosmic time with JWST |
| topic | Astrophysics of Galaxies Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2512.07955 |