@article{22817,
  abstract     = {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.},
  author       = {Schaerer, D. and Izotov, Y. I. and Marques-Chaves, R. and Steidel, C. C. and Reddy, N. and Shapley, A. E. and Mascia, Sara and Chisholm, J. and Flury, S. R. and Guseva, N. and Heckman, T. and Henry, A. and Inoue, A. K. and Jung, I. and Kusakabe, H. and Mawatari, K. and Oesch, P. and Östlin, G. and Pentericci, L. and Roy, N. and Saldana-Lopez, A. and Sato, R. and Vanzella, E. and Verhamme, A. and Wang, B.},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  publisher    = {EDP Sciences},
  title        = {{Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated}},
  doi          = {10.1051/0004-6361/202556832},
  volume       = {708},
  year         = {2026},
}