EDGE-INFERNO: How chemical enrichment assumptions impact the individual stars of a simulated ultra-faint dwarf galaxy

Eric P. Andersson; Martin P. Rey; Robert M. Yates; Justin I. Read; Oscar Agertz; Alexander P. Ji; Jennifer Mead; Kaley Brauer; Mordecai Mark Mac Low

doi:10.1051/0004-6361/202558029

EDGE-INFERNO: How chemical enrichment assumptions impact the individual stars of a simulated ultra-faint dwarf galaxy

Eric P. Andersson, Martin P. Rey, Robert M. Yates, Justin I. Read, Oscar Agertz, Alexander P. Ji, Jennifer Mead, Kaley Brauer, Mordecai Mark Mac Low

Research output: Contribution to journal › Article › peer-review

Abstract

The chemical abundances of stars in galaxies are a fossil record of the star formation and stellar evolution processes that regulate galaxy formation, including the stellar initial mass function, the fraction and timing of type Ia supernovae (SNeIa), and nucleosynthesis inside massive stars. In this paper, we systematically explore uncertainties associated with modeling chemical enrichment in dwarf galaxies. We repeatedly simulate a single EDGE-INFERNO dwarf (M _★ ≈ 10⁵ M _⊙), varying the chemical yields of massive stars, the timing and yields of SNeIa, and the intrinsic stochasticity that arises from sampling individual stars and galaxy formation chaoticity. All simulations are high-resolution (3.6 pc), cosmological zoom-in hydrodynamical simulations that track the stellar evolution of all individual stars with masses of > 0.5 M_⊙. We find that SNeIa make significant contributions to the iron content of low-mass, reionization-limited galaxies, with possible variations in mean abundance ratios and [Fe/H] related to minor changes in their evolutionary timescales. In contrast, different massive star yields, accounting (or not) for stellar rotation, result in mean abundance variations comparable to those arising from stochasticity, with the possible exception of extremely rapidly rotating stars. Nonetheless, massive stars significantly affect the shape of abundance trends with [Fe/H], for example, through the existence (or not) of a bimodality in the [X/Fe]–[Fe/H] planes, particularly in [Al/Fe]. Finally, we find that the variance arising from random sampling severely limits the interpretation of single galaxies. Our analysis showcases the power of star-by-star cosmological models to unpick how both systematic uncertainties (e.g., assumptions in low-metallicity chemical enrichment) and statistical uncertainties (e.g., averaging over enough galaxies and stars within a galaxy) affect the interpretation of chemical observables in ultra-faint dwarf galaxies.

Original language	English
Article number	A112
Number of pages	16
Journal	Astronomy and Astrophysics
Volume	707
Early online date	1 Mar 2026
DOIs	https://doi.org/10.1051/0004-6361/202558029
Publication status	Published - 1 Mar 2026

Funding

We thank the anonymous reviewer for thoughtful comments, which improved the quality of this work. The authors thank Marco Limongi, Kira Lund, Stacy Kim, Pilar Gil Pons and Brian Schmidt for insightful discussions during the buildup of this work and comments on an earlier version of the manuscript. EPA and M-MML acknowledge support from NASA ATP grant 80NSSC24K0935 and NSF grant AST23-0795. JIR would like to acknowledge support from STFC grants ST/Y002865/1 and ST/Y002857/1. OA acknowledges support from the Knut and Alice Wallenberg Foundation, the Swedish National Space Agency (SNSA Dnr 2023-00164), and the LMK foundation. A.P.J. acknowledges support from the National Science Foundation under grant AST-2307599 and the Alfred P. Sloan Foundation. J.M. acknowledges support from the NSF Graduate Research Fellowship Program through grant DGE2036197. K.B. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2303858. This work made extensive use of the dp191 and dp324 projects on the STFC-DiRAC ecosystem. This work was performed using the DiRAC Data Intensive service at Leicester, operated by the University of Leicester IT Services, which forms part of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The equipment was funded by BEIS capital funding via STFC capital grants ST/K000373/1, ST/R002363/1, and STFC DiRAC Operations grant ST/R001014/1.

Keywords

galaxies: abundances
galaxies: dwarf
galaxies: formation

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1051/0004-6361/202558029Licence: CC BY

Cite this

@article{f221c98c3de94a49b9ecb59889f48b23,

title = "EDGE-INFERNO: How chemical enrichment assumptions impact the individual stars of a simulated ultra-faint dwarf galaxy",

abstract = "The chemical abundances of stars in galaxies are a fossil record of the star formation and stellar evolution processes that regulate galaxy formation, including the stellar initial mass function, the fraction and timing of type Ia supernovae (SNeIa), and nucleosynthesis inside massive stars. In this paper, we systematically explore uncertainties associated with modeling chemical enrichment in dwarf galaxies. We repeatedly simulate a single EDGE-INFERNO dwarf (M ★ ≈ 105 M ⊙), varying the chemical yields of massive stars, the timing and yields of SNeIa, and the intrinsic stochasticity that arises from sampling individual stars and galaxy formation chaoticity. All simulations are high-resolution (3.6 pc), cosmological zoom-in hydrodynamical simulations that track the stellar evolution of all individual stars with masses of > 0.5 M⊙. We find that SNeIa make significant contributions to the iron content of low-mass, reionization-limited galaxies, with possible variations in mean abundance ratios and [Fe/H] related to minor changes in their evolutionary timescales. In contrast, different massive star yields, accounting (or not) for stellar rotation, result in mean abundance variations comparable to those arising from stochasticity, with the possible exception of extremely rapidly rotating stars. Nonetheless, massive stars significantly affect the shape of abundance trends with [Fe/H], for example, through the existence (or not) of a bimodality in the [X/Fe]–[Fe/H] planes, particularly in [Al/Fe]. Finally, we find that the variance arising from random sampling severely limits the interpretation of single galaxies. Our analysis showcases the power of star-by-star cosmological models to unpick how both systematic uncertainties (e.g., assumptions in low-metallicity chemical enrichment) and statistical uncertainties (e.g., averaging over enough galaxies and stars within a galaxy) affect the interpretation of chemical observables in ultra-faint dwarf galaxies.",

keywords = "galaxies: abundances, galaxies: dwarf, galaxies: formation",

author = "Andersson, \{Eric P.\} and Rey, \{Martin P.\} and Yates, \{Robert M.\} and Read, \{Justin I.\} and Oscar Agertz and Ji, \{Alexander P.\} and Jennifer Mead and Kaley Brauer and \{Mac Low\}, \{Mordecai Mark\}",

year = "2026",

month = mar,

day = "1",

doi = "10.1051/0004-6361/202558029",

language = "English",

volume = "707",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - EDGE-INFERNO

T2 - How chemical enrichment assumptions impact the individual stars of a simulated ultra-faint dwarf galaxy

AU - Andersson, Eric P.

AU - Rey, Martin P.

AU - Yates, Robert M.

AU - Read, Justin I.

AU - Agertz, Oscar

AU - Ji, Alexander P.

AU - Mead, Jennifer

AU - Brauer, Kaley

AU - Mac Low, Mordecai Mark

PY - 2026/3/1

Y1 - 2026/3/1

N2 - The chemical abundances of stars in galaxies are a fossil record of the star formation and stellar evolution processes that regulate galaxy formation, including the stellar initial mass function, the fraction and timing of type Ia supernovae (SNeIa), and nucleosynthesis inside massive stars. In this paper, we systematically explore uncertainties associated with modeling chemical enrichment in dwarf galaxies. We repeatedly simulate a single EDGE-INFERNO dwarf (M ★ ≈ 105 M ⊙), varying the chemical yields of massive stars, the timing and yields of SNeIa, and the intrinsic stochasticity that arises from sampling individual stars and galaxy formation chaoticity. All simulations are high-resolution (3.6 pc), cosmological zoom-in hydrodynamical simulations that track the stellar evolution of all individual stars with masses of > 0.5 M⊙. We find that SNeIa make significant contributions to the iron content of low-mass, reionization-limited galaxies, with possible variations in mean abundance ratios and [Fe/H] related to minor changes in their evolutionary timescales. In contrast, different massive star yields, accounting (or not) for stellar rotation, result in mean abundance variations comparable to those arising from stochasticity, with the possible exception of extremely rapidly rotating stars. Nonetheless, massive stars significantly affect the shape of abundance trends with [Fe/H], for example, through the existence (or not) of a bimodality in the [X/Fe]–[Fe/H] planes, particularly in [Al/Fe]. Finally, we find that the variance arising from random sampling severely limits the interpretation of single galaxies. Our analysis showcases the power of star-by-star cosmological models to unpick how both systematic uncertainties (e.g., assumptions in low-metallicity chemical enrichment) and statistical uncertainties (e.g., averaging over enough galaxies and stars within a galaxy) affect the interpretation of chemical observables in ultra-faint dwarf galaxies.

AB - The chemical abundances of stars in galaxies are a fossil record of the star formation and stellar evolution processes that regulate galaxy formation, including the stellar initial mass function, the fraction and timing of type Ia supernovae (SNeIa), and nucleosynthesis inside massive stars. In this paper, we systematically explore uncertainties associated with modeling chemical enrichment in dwarf galaxies. We repeatedly simulate a single EDGE-INFERNO dwarf (M ★ ≈ 105 M ⊙), varying the chemical yields of massive stars, the timing and yields of SNeIa, and the intrinsic stochasticity that arises from sampling individual stars and galaxy formation chaoticity. All simulations are high-resolution (3.6 pc), cosmological zoom-in hydrodynamical simulations that track the stellar evolution of all individual stars with masses of > 0.5 M⊙. We find that SNeIa make significant contributions to the iron content of low-mass, reionization-limited galaxies, with possible variations in mean abundance ratios and [Fe/H] related to minor changes in their evolutionary timescales. In contrast, different massive star yields, accounting (or not) for stellar rotation, result in mean abundance variations comparable to those arising from stochasticity, with the possible exception of extremely rapidly rotating stars. Nonetheless, massive stars significantly affect the shape of abundance trends with [Fe/H], for example, through the existence (or not) of a bimodality in the [X/Fe]–[Fe/H] planes, particularly in [Al/Fe]. Finally, we find that the variance arising from random sampling severely limits the interpretation of single galaxies. Our analysis showcases the power of star-by-star cosmological models to unpick how both systematic uncertainties (e.g., assumptions in low-metallicity chemical enrichment) and statistical uncertainties (e.g., averaging over enough galaxies and stars within a galaxy) affect the interpretation of chemical observables in ultra-faint dwarf galaxies.

KW - galaxies: abundances

KW - galaxies: dwarf

KW - galaxies: formation

UR - https://www.scopus.com/pages/publications/105031763856

U2 - 10.1051/0004-6361/202558029

DO - 10.1051/0004-6361/202558029

M3 - Article

AN - SCOPUS:105031763856

SN - 0004-6361

VL - 707

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A112

ER -

EDGE-INFERNO: How chemical enrichment assumptions impact the individual stars of a simulated ultra-faint dwarf galaxy

Abstract

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this