Modelling the broken age-[Fe/H] relation and metallicity distribution function of mono-age populations
Abstract
This study investigates the chemical evolution history and radial migration in the Milky Way utilizing high-precision age measurements based on large-scale stellar spectroscopic surveys. Recent observational data have revealed a distinct break in the age-metallicity relation of stars in the solar neighborhood, suggesting that stellar populations of the Milky Way can be divided into two evolutionary sequences. Based on galactic chemical evolution models, we confirm that this break in the age-metallicity relation can be explained by a recent major gas accretion event, which diluted the metallicity in the disk and triggered a starburst, leading to the formation of an independent age-metallicity sequence. To assess the impact of stellar radial migration, we incorporate a simplified treatment of this process into our multi-zone chemical evolution model. Radial migration is modeled as a probabilistic diffusion process, characterized by a Gaussian distribution. By fitting the model-predicted metallicity distribution functions (MDFs) of mono-age stellar populations to observations, we infer a migration strength of σ= 2.15+0.100−0.103 kpc for stars with ages between 2 and 6 Gyr located at 9.5-11.5 kpc, corresponding to an average radial displacement of 1.92 kpc over 10 Gyr. This result is lower than previous estimates of stellar radial migration, suggesting that the role of radial migration in shaping the chemical structure of the Milky Way is less important than previously estimated.
Related
- Cluster Ages to Reconstruct the Milky Way Assembly (CARMA). VI. The age-metallicity relation of in situ clusters and the age of the Universe
- Re-evaluating the resolved mass-metallicity relation with a self-consistent metallicity calibration
- Mass-Metallicity Relation of the Fossil Disk in Six Nearby Galaxies using JWST RGB Stars
- ALMA Chemical Evolution (ACE) survey: The gas fundamental metallicity relation at cosmic noon
- Episodic Star Formation - II. The Origin of the Fundamental Metallicity Relation
BibTeX
@misc{shao2026modelling,
title = {{Modelling the broken age-[Fe/H] relation and metallicity distribution function of mono-age populations}},
author = {Qinhao Shao and Jianhui Lian},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.15295},
eprint = {2610.15295},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.15295},
}
RIS
TY - UNPB
TI - Modelling the broken age-[Fe/H] relation and metallicity distribution function of mono-age populations
AU - Qinhao Shao
AU - Jianhui Lian
PY - 2026
DA - 2026/10/11
PB - arXiv
DO - 10.48550/arxiv.2610.15295
UR - https://arxiv.org/abs/2610.15295
AB - This study investigates the chemical evolution history and radial migration in the Milky Way utilizing high-precision age measurements based on large-scale stellar spectroscopic surveys. Recent observational data have revealed a distinct break in the age-metallicity relation of stars in the solar neighborhood, suggesting that stellar populations of the Milky Way can be divided into two evolutionary sequences. Based on galactic chemical evolution models, we confirm that this break in the age-metallicity relation can be explained by a recent major gas accretion event, which diluted the metallicity in the disk and triggered a starburst, leading to the formation of an independent age-metallicity sequence. To assess the impact of stellar radial migration, we incorporate a simplified treatment of this process into our multi-zone chemical evolution model. Radial migration is modeled as a probabilistic diffusion process, characterized by a Gaussian distribution. By fitting the model-predicted metallicity distribution functions (MDFs) of mono-age stellar populations to observations, we infer a migration strength of σ= 2.15^+0.100_−0.103 kpc for stars with ages between 2 and 6 Gyr located at 9.5-11.5 kpc, corresponding to an average radial displacement of 1.92 kpc over 10 Gyr. This result is lower than previous estimates of stellar radial migration, suggesting that the role of radial migration in shaping the chemical structure of the Milky Way is less important than previously estimated.
ER -