How Quickly Did the Giants Form? Constraining the Formation Timescales of Massive Quiescent Galaxies at Cosmic Noon Using Chemical Evolution Modelling
Abstract
Massive quiescent galaxies (MQGs; M⋆ ∼ 1011 M⊙) at cosmic noon (z ∼ 2) host α-enhanced stellar populations ([Mg/Fe] ∼ 0.4 − 0.5) at near-solar [Fe/H], implying rapid formation histories that spectral energy distribution (SED) fitting alone constrains poorly. To determine the physical conditions and formation timescales that generate these abundances, we employ a one-zone chemical evolution model with nucleosynthetic yields calibrated against resolved stars in the Sculptor dwarf spheroidal. Comparing our model to a compilation of observed abundances, we find MQGs are consistent with rapid formation timescales of ΔtSF ∼ 0.1 − 0.4 Gyr. The progenitors must sustain high star-formation efficiencies (approximately the molecular gas depletion time; τ⋆ ∼ 0.05 Gyr) and retain most of their metal-enriched ejecta (η∼ 0), consistent with high-redshift dusty star-forming galaxies (DSFGs). However, our model favours moderately active progenitors with typical star-formation rates (SFRs) of 200−400 M⊙ yr−1, matching recently identified `NIRCam-dark' galaxies more closely than the broader DSFG population. Sustained starbursts (SFR ≳ 1000 M⊙ yr−1) are disfavoured, since they would form most stellar mass before significant SN Ia enrichment and underproduce the observed [Fe/H]. The same framework also reproduces the central abundances of local early-type galaxies over longer timescales (ΔtSF ∼ 0.6 − 1 Gyr). Chemical abundances can therefore provide powerful constraints on the formation histories of MQGs, and incorporating them into SED-fitting routines will ensure inferred histories remain consistent with the observed chemistry.
Related
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- Quiescent galaxies at cosmic noon: from individual element abundances to star formation histories
- DeepDive: Simultaneous Formation of Massive Quiescent Galaxies in High-redshift Galaxy Overdensities
BibTeX
@misc{oconnor2026quickly,
title = {{How Quickly Did the Giants Form? Constraining the Formation Timescales of Massive Quiescent Galaxies at Cosmic Noon Using Chemical Evolution Modelling}},
author = {Patrick N. O'Connor and J. Trevor Mendel and Sven Buder and Melissa K. Ness and Claudia del P. Lagos and Arjen van der Wel},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34883},
eprint = {2610.34883},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34883},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - How Quickly Did the Giants Form? Constraining the Formation Timescales of Massive Quiescent Galaxies at Cosmic Noon Using Chemical Evolution Modelling
AU - Patrick N. O'Connor
AU - J. Trevor Mendel
AU - Sven Buder
AU - Melissa K. Ness
AU - Claudia del P. Lagos
AU - Arjen van der Wel
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.34883
UR - https://arxiv.org/abs/2610.34883
AB - Massive quiescent galaxies (MQGs; M_⋆ ∼ 10^11 M_⊙) at cosmic noon (z ∼ 2) host α-enhanced stellar populations ([Mg/Fe] ∼ 0.4 − 0.5) at near-solar [Fe/H], implying rapid formation histories that spectral energy distribution (SED) fitting alone constrains poorly. To determine the physical conditions and formation timescales that generate these abundances, we employ a one-zone chemical evolution model with nucleosynthetic yields calibrated against resolved stars in the Sculptor dwarf spheroidal. Comparing our model to a compilation of observed abundances, we find MQGs are consistent with rapid formation timescales of Δt_SF ∼ 0.1 − 0.4 Gyr. The progenitors must sustain high star-formation efficiencies (approximately the molecular gas depletion time; τ_⋆ ∼ 0.05 Gyr) and retain most of their metal-enriched ejecta (η∼ 0), consistent with high-redshift dusty star-forming galaxies (DSFGs). However, our model favours moderately active progenitors with typical star-formation rates (SFRs) of 200−400 M_⊙ yr^−1, matching recently identified `NIRCam-dark' galaxies more closely than the broader DSFG population. Sustained starbursts (SFR ≳ 1000 M_⊙ yr^−1) are disfavoured, since they would form most stellar mass before significant SN Ia enrichment and underproduce the observed [Fe/H]. The same framework also reproduces the central abundances of local early-type galaxies over longer timescales (Δt_SF ∼ 0.6 − 1 Gyr). Chemical abundances can therefore provide powerful constraints on the formation histories of MQGs, and incorporating them into SED-fitting routines will ensure inferred histories remain consistent with the observed chemistry.
ER -