CLASSY XII: nitrogen enrichment shaped by gas density and feedback

K Z Arellano-Córdova; D A Berg; M Mingozzi; B L James; F Vincenzo; N S J Rogers; E D Skillman; R O Amorín; F Cullen; S R Flury; V Abril-Melgarejo; J Chisholm; T Heckman; M J Hayes; S Hernandez; N Kumari; C Kobayashi; C Leitherer; C L Martin; Z Martinez; T Nanayakkara; K S Parker; P Senchyna; C Scarlata; M G Stephenson; A Wofford; X Xu; P Zhu

doi:10.1093/mnras/staf1723

CLASSY XII: nitrogen enrichment shaped by gas density and feedback

K Z Arellano-Córdova
, D A Berg
, M Mingozzi
, B L James
, F Vincenzo
, N S J Rogers
, E D Skillman
, R O Amorín
, F Cullen
, S R Flury
, V Abril-Melgarejo
, J Chisholm
, T Heckman
, M J Hayes
, S Hernandez
, N Kumari
, C Kobayashi
, C Leitherer
, C L Martin
, Z Martinez

T Nanayakkara, K S Parker, P Senchyna, C Scarlata, M G Stephenson, A Wofford, X Xu, P Zhu

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Abstract

We investigate the chemical evolution of N/O using a sample of 45 local star-forming galaxies from the CLASSY survey. This sample spans a wide range of galaxy properties, with robust determinations of nitrogen and oxygen abundances via the direct- method. We explore how N/O relates to density structure, stellar mass, star formation rate (SFR), stellar age, compactness, and gas kinematics. In addition, we compare our results with those of galaxies at where N/O ratios were derived from optical or UV nitrogen lines, aiming to identify chemical enrichment pathways across cosmic time. Our analysis shows that the N/O–O/H relation in CLASSY galaxies aligns with the trends seen in local galaxies and extragalactic H ii regions, and that galaxies at exhibit similar N/O values, indicating no significant redshift evolution in N/O for a fixed metallicity. We identify a significant correlation between electron density ([S ii]) and N/O, suggesting that density structure contributes to the scatter in the N/O–O/H relation. The CLASSY galaxies with high SFRs or compact star formation show elevated N/O, though no strong correlation with stellar mass is found. We also find that high-velocity outflows ( km s−1) and low mass-loading factors are linked to elevated N/O, indicating that feedback plays a significant role. These results highlight the importance of density, star formation, and feedback from young stellar populations in shaping N/O enrichment and provide key insights for interpreting high- galaxies observed with James Webb Space Telescope.

Original language	English
Pages (from-to)	1588-1607
Number of pages	20
Journal	Monthly Notices of the Royal Astronomical Society
Volume	544
Issue number	2
Early online date	9 Oct 2025
DOIs	https://doi.org/10.1093/mnras/staf1723
Publication status	Published - 31 Dec 2025

Keywords

galaxies: evolution
galaxies: abundances
galaxies: dwarf
galaxies: ISM
galaxies: kinematics and dynamics

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10.1093/mnras/staf1723Licence: CC BY

Final_versionFinal published version, 3.63 MBLicence: CC BY

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Arellano-Córdova, K. Z., Berg, D. A., Mingozzi, M., James, B. L., Vincenzo, F., Rogers, N. S. J., Skillman, E. D., Amorín, R. O., Cullen, F., Flury, S. R., Abril-Melgarejo, V., Chisholm, J., Heckman, T., Hayes, M. J., Hernandez, S., Kumari, N., Kobayashi, C., Leitherer, C., Martin, C. L., ... Zhu, P. (2025). CLASSY XII: nitrogen enrichment shaped by gas density and feedback. Monthly Notices of the Royal Astronomical Society, 544(2), 1588-1607. https://doi.org/10.1093/mnras/staf1723

@article{73c711b96f5844f3bf8abb062b7d89cc,

title = "CLASSY XII: nitrogen enrichment shaped by gas density and feedback",

abstract = "We investigate the chemical evolution of N/O using a sample of 45 local star-forming galaxies from the CLASSY survey. This sample spans a wide range of galaxy properties, with robust determinations of nitrogen and oxygen abundances via the direct- method. We explore how N/O relates to density structure, stellar mass, star formation rate (SFR), stellar age, compactness, and gas kinematics. In addition, we compare our results with those of galaxies at where N/O ratios were derived from optical or UV nitrogen lines, aiming to identify chemical enrichment pathways across cosmic time. Our analysis shows that the N/O{\textendash}O/H relation in CLASSY galaxies aligns with the trends seen in local galaxies and extragalactic H ii regions, and that galaxies at exhibit similar N/O values, indicating no significant redshift evolution in N/O for a fixed metallicity. We identify a significant correlation between electron density ([S ii]) and N/O, suggesting that density structure contributes to the scatter in the N/O{\textendash}O/H relation. The CLASSY galaxies with high SFRs or compact star formation show elevated N/O, though no strong correlation with stellar mass is found. We also find that high-velocity outflows ( km s−1) and low mass-loading factors are linked to elevated N/O, indicating that feedback plays a significant role. These results highlight the importance of density, star formation, and feedback from young stellar populations in shaping N/O enrichment and provide key insights for interpreting high- galaxies observed with James Webb Space Telescope.",

keywords = "galaxies: evolution, galaxies: abundances, galaxies: dwarf, galaxies: ISM, galaxies: kinematics and dynamics",

author = "Arellano-C{\'o}rdova, \{K Z\} and Berg, \{D A\} and M Mingozzi and James, \{B L\} and F Vincenzo and Rogers, \{N S J\} and Skillman, \{E D\} and Amor{\'i}n, \{R O\} and F Cullen and Flury, \{S R\} and V Abril-Melgarejo and J Chisholm and T Heckman and Hayes, \{M J\} and S Hernandez and N Kumari and C Kobayashi and C Leitherer and Martin, \{C L\} and Z Martinez and T Nanayakkara and Parker, \{K S\} and P Senchyna and C Scarlata and Stephenson, \{M G\} and A Wofford and X Xu and P Zhu",

note = "{\textcopyright} The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/).",

year = "2025",

month = dec,

day = "31",

doi = "10.1093/mnras/staf1723",

language = "English",

volume = "544",

pages = "1588--1607",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press (OUP)",

number = "2",

}

Arellano-Córdova, KZ, Berg, DA, Mingozzi, M, James, BL, Vincenzo, F, Rogers, NSJ, Skillman, ED, Amorín, RO, Cullen, F, Flury, SR, Abril-Melgarejo, V, Chisholm, J, Heckman, T, Hayes, MJ, Hernandez, S, Kumari, N, Kobayashi, C, Leitherer, C, Martin, CL, Martinez, Z, Nanayakkara, T, Parker, KS, Senchyna, P, Scarlata, C, Stephenson, MG, Wofford, A, Xu, X & Zhu, P 2025, 'CLASSY XII: nitrogen enrichment shaped by gas density and feedback', Monthly Notices of the Royal Astronomical Society, vol. 544, no. 2, pp. 1588-1607. https://doi.org/10.1093/mnras/staf1723

TY - JOUR

T1 - CLASSY XII: nitrogen enrichment shaped by gas density and feedback

AU - Arellano-Córdova, K Z

AU - Berg, D A

AU - Mingozzi, M

AU - James, B L

AU - Vincenzo, F

AU - Rogers, N S J

AU - Skillman, E D

AU - Amorín, R O

AU - Cullen, F

AU - Flury, S R

AU - Abril-Melgarejo, V

AU - Chisholm, J

AU - Heckman, T

AU - Hayes, M J

AU - Hernandez, S

AU - Kumari, N

AU - Kobayashi, C

AU - Leitherer, C

AU - Martin, C L

AU - Martinez, Z

AU - Nanayakkara, T

AU - Parker, K S

AU - Senchyna, P

AU - Scarlata, C

AU - Stephenson, M G

AU - Wofford, A

AU - Xu, X

AU - Zhu, P

N1 - © The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/).

PY - 2025/12/31

Y1 - 2025/12/31

N2 - We investigate the chemical evolution of N/O using a sample of 45 local star-forming galaxies from the CLASSY survey. This sample spans a wide range of galaxy properties, with robust determinations of nitrogen and oxygen abundances via the direct- method. We explore how N/O relates to density structure, stellar mass, star formation rate (SFR), stellar age, compactness, and gas kinematics. In addition, we compare our results with those of galaxies at where N/O ratios were derived from optical or UV nitrogen lines, aiming to identify chemical enrichment pathways across cosmic time. Our analysis shows that the N/O–O/H relation in CLASSY galaxies aligns with the trends seen in local galaxies and extragalactic H ii regions, and that galaxies at exhibit similar N/O values, indicating no significant redshift evolution in N/O for a fixed metallicity. We identify a significant correlation between electron density ([S ii]) and N/O, suggesting that density structure contributes to the scatter in the N/O–O/H relation. The CLASSY galaxies with high SFRs or compact star formation show elevated N/O, though no strong correlation with stellar mass is found. We also find that high-velocity outflows ( km s−1) and low mass-loading factors are linked to elevated N/O, indicating that feedback plays a significant role. These results highlight the importance of density, star formation, and feedback from young stellar populations in shaping N/O enrichment and provide key insights for interpreting high- galaxies observed with James Webb Space Telescope.

AB - We investigate the chemical evolution of N/O using a sample of 45 local star-forming galaxies from the CLASSY survey. This sample spans a wide range of galaxy properties, with robust determinations of nitrogen and oxygen abundances via the direct- method. We explore how N/O relates to density structure, stellar mass, star formation rate (SFR), stellar age, compactness, and gas kinematics. In addition, we compare our results with those of galaxies at where N/O ratios were derived from optical or UV nitrogen lines, aiming to identify chemical enrichment pathways across cosmic time. Our analysis shows that the N/O–O/H relation in CLASSY galaxies aligns with the trends seen in local galaxies and extragalactic H ii regions, and that galaxies at exhibit similar N/O values, indicating no significant redshift evolution in N/O for a fixed metallicity. We identify a significant correlation between electron density ([S ii]) and N/O, suggesting that density structure contributes to the scatter in the N/O–O/H relation. The CLASSY galaxies with high SFRs or compact star formation show elevated N/O, though no strong correlation with stellar mass is found. We also find that high-velocity outflows ( km s−1) and low mass-loading factors are linked to elevated N/O, indicating that feedback plays a significant role. These results highlight the importance of density, star formation, and feedback from young stellar populations in shaping N/O enrichment and provide key insights for interpreting high- galaxies observed with James Webb Space Telescope.

KW - galaxies: evolution

KW - galaxies: abundances

KW - galaxies: dwarf

KW - galaxies: ISM

KW - galaxies: kinematics and dynamics

U2 - 10.1093/mnras/staf1723

DO - 10.1093/mnras/staf1723

M3 - Article

SN - 0035-8711

VL - 544

SP - 1588

EP - 1607

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

CLASSY XII: nitrogen enrichment shaped by gas density and feedback

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Keywords

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