EDGE-INFERNO: The chemical signatures of assembly history in reionization fossils
Abstract
In galaxies, stellar populations represent a superposition of both in situ and accreted components, tracing internal chemical evolution as well as the histories of merged satellites. We investigate how assembly history shapes the chemical properties of present-day stellar populations in low-mass dwarf galaxies. We analyze a suite of EDGE-INFERNO star-by-star cosmological zoom-in simulations of galaxies with present-day halo mass ∼1.4×109 M⊙. We systematically vary galaxy growth while preserving the present-day halo mass, engineering our simulations to span a continuum of assembly histories. Early-forming systems form most of their stars in a single progenitor, with centrally concentrated star formation and a continuous enrichment history. In contrast, our late-forming systems assemble by accretion of multiple progenitors with their own stellar populations, resulting in fragmented star formation across several halos with independent chemical evolution tracks. These regimes produce qualitatively different chemical signatures: single-progenitor systems exhibit connected, well-defined trends in abundance space, while multi-progenitor systems show multiple, distinct stellar populations with limited overlap. We find that metallicity distribution functions provide initial constraints on assembly history for samples of at least $50−100$ member stars. Multi-element abundance analysis significantly improves the recovery of distinct components, although robust reconstruction still requires larger samples. Fully separating in situ and accreted populations likely requires kinematic information. Accreted stars can contribute substantially even at high metallicities in multi-progenitor systems, while external enrichment can cause accreted material to follow similar chemical trends as in situ stars, particularly in the single-progenitor regime.
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BibTeX
@misc{andersson2026edgeinferno,
title = {{EDGE-INFERNO: The chemical signatures of assembly history in reionization fossils}},
author = {Eric P. Andersson and Martin P. Rey and Alexander P. Ji and Justin I. Read and Oscar Agertz and Alexander H. Riley and Stacy Y. Kim and Astha Chaturvedi and Jennifer Mead and Kaley Brauer and Mordecai-Mark Mac Low and Andrew Pontzen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18473},
eprint = {2610.18473},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18473},
}
RIS
TY - UNPB
TI - EDGE-INFERNO: The chemical signatures of assembly history in reionization fossils
AU - Eric P. Andersson
AU - Martin P. Rey
AU - Alexander P. Ji
AU - Justin I. Read
AU - Oscar Agertz
AU - Alexander H. Riley
AU - Stacy Y. Kim
AU - Astha Chaturvedi
AU - Jennifer Mead
AU - Kaley Brauer
AU - Mordecai-Mark Mac Low
AU - Andrew Pontzen
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18473
UR - https://arxiv.org/abs/2610.18473
AB - In galaxies, stellar populations represent a superposition of both in situ and accreted components, tracing internal chemical evolution as well as the histories of merged satellites. We investigate how assembly history shapes the chemical properties of present-day stellar populations in low-mass dwarf galaxies. We analyze a suite of EDGE-INFERNO star-by-star cosmological zoom-in simulations of galaxies with present-day halo mass ∼1.4×10^9 M_⊙. We systematically vary galaxy growth while preserving the present-day halo mass, engineering our simulations to span a continuum of assembly histories. Early-forming systems form most of their stars in a single progenitor, with centrally concentrated star formation and a continuous enrichment history. In contrast, our late-forming systems assemble by accretion of multiple progenitors with their own stellar populations, resulting in fragmented star formation across several halos with independent chemical evolution tracks. These regimes produce qualitatively different chemical signatures: single-progenitor systems exhibit connected, well-defined trends in abundance space, while multi-progenitor systems show multiple, distinct stellar populations with limited overlap. We find that metallicity distribution functions provide initial constraints on assembly history for samples of at least $50−100$ member stars. Multi-element abundance analysis significantly improves the recovery of distinct components, although robust reconstruction still requires larger samples. Fully separating in situ and accreted populations likely requires kinematic information. Accreted stars can contribute substantially even at high metallicities in multi-progenitor systems, while external enrichment can cause accreted material to follow similar chemical trends as in situ stars, particularly in the single-progenitor regime.
ER -