Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated Schaerer, D. Izotov, Y. I. Marques-Chaves, R. Steidel, C. C. Reddy, N. Shapley, A. E. Mascia, Sara Chisholm, J. Flury, S. R. Guseva, N. Heckman, T. Henry, A. Inoue, A. K. Jung, I. Kusakabe, H. Mawatari, K. Oesch, P. Östlin, G. Pentericci, L. Roy, N. Saldana-Lopez, A. Sato, R. Vanzella, E. Verhamme, A. Wang, B. ddc:520 Using deep, medium-resolution, JWST rest-optical spectra of a sample of typical star-forming galaxies (Lyman-break galaxies and Lyman-α emitters) from the LyC22 survey at z ∼ 3, we determined the nebular abundances of N, O, and Ne relative to H for a subsample of 25 objects with a direct method based on auroral [O III] λ4363 line detections. Our measurements increased the number of accurate N/O determinations at z ∼ 2 − 4 using a homogeneous approach. We found a mean value of log(N/O) = −+0.25−0.21 over a metallicity range of 12 + log(O/H) = 7.56 to 8.44. The observed N/O ratio and scatter are indistinguishable from that observed in low-z galaxies and H II regions over the same metallicity range, thus showing no redshift evolution of N/O for typical galaxies over a significant fraction of cosmic time. We also show that typical z ∼ 3 galaxies have a similar offset in the BPT diagram to galaxies from the low-z Lyman Continuum Survey (LzLCS) when compared to the average of SDSS galaxies, and we demonstrate that this offset is not due to enhanced nitrogen abundances. Our results establish a basis for future studies of the evolution of N and O at higher redshifts. EDP Sciences 2026 info:eu-repo/semantics/article doc-type:article article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/22817 https://research-explorer.ista.ac.at/download/22817/22890 Schaerer D, Izotov YI, Marques-Chaves R, et al. Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated. <i>Astronomy &#38; Astrophysics</i>. 2026;708. doi:<a href="https://doi.org/10.1051/0004-6361/202556832">10.1051/0004-6361/202556832</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/202556832 info:eu-repo/semantics/altIdentifier/issn/0004-6361 info:eu-repo/semantics/altIdentifier/e-issn/1432-0746 info:eu-repo/semantics/altIdentifier/arxiv/2601.06968 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess