Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.15295

Modelling the broken age-[Fe/H] relation and metallicity distribution function of mono-age populations

Qinhao Shao·Jianhui Lian
View original source ↗Read source document ↗Export metadata ↓

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 $σ= 2.15^{+0.100}_{-0.103}\,{\rm kpc}$ 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.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Qinhao Shao, Jianhui Lian. 2026-10-11. Modelling the broken age-[Fe/H] relation and metallicity distribution function of mono-age populations. https://arxiv.org/abs/2610.15295

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Beneath the Surface: >85% of z>5.9 QSOs in Massive Host Galaxies are UV-Faint

We use [CII] observations of a large quasi-stellar object (QSO) sample to segregate sources by host galaxy mass, aiming to identify those in the most massive hosts. [CII] luminosity, a known tracer of molecular gas, is taken as a proxy for host mass and used to rank 190 QSOs at z>5.9, spanning a 6-mag UV luminosity range (-22 -24.5) and 25 especially UV-faint (Muv>-23.5) QSOs, improving statistics by 5x and 6x, respectively. Taking massive host galaxies to be those where L[CII]>1.8x10^9 Lsol (median L[CII] of UV-bright QSOs), we identify 61 QSOs, including 13 which are UV-faint and 7 especially UV-faint. Using these selections and recent QSO luminosity functions (LFs), we present the first characterization of UV luminosity distribution for QSOs in massive host galaxies and quantify [CII] LFs for both UV-bright and UV-faint QSOs. While ~3% of massive-host QSOs are UV-bright (Muv<-26), >~85% are UV-faint (Muv>-24.5). This wide dispersion in UV luminosities reflects variations in dust obscuration, accretion efficiency, and black hole mass. Though spectroscopy is needed for definitive conclusions, black hole mass appears to be the dominant factor driving variations in the UV luminosity, based on 34 [CII]-luminous (L[CII]>1.8x10^9 Lsol) QSOs distributed across a ~3-mag baseline in UV luminosity and with measured MBH. At Muv~-23, the median extrapolated log10 (MBH/Msol) is 8.1+/-0.4, consistent with the local relation. Supermassive black holes (SMBHs) in UV-bright QSOs thus appear to be ~15(-9)(+25)x more massive than typical for massive host galaxies at z~6.

astro-ph.GA↗
arXiv2026

Learning to See Sharper: A Physics-Informed Artificial Intelligence Framework for Super-Resolving Galaxy Spectra

The information recoverable from galaxy spectra depends fundamentally on spectral resolution, yet assembling large samples at high resolution remains observationally expensive. We present a deep-learning framework for spectral super-resolution that enhances low-resolution galaxy spectra by a factor of $\sim$10 in resolving power ($R\sim100$ to $R\sim1000$). The model is trained on 2,858 paired JWST/NIRSpec observations from the JADES program, where low-resolution prism spectra are matched with medium-resolution grating spectra (G140M, G235M, G395M) combined into a unified reference covering $1.0-5.3μ\mathrm{m}$. Our three-stage architecture performs an initial super-resolution, infers the redshift from the coarse reconstruction, and then applies a physics-informed residual refinement that uses attention across emission-line tokens to learn inter-line relationships and predict parametric line profiles, alongside a convolutional branch for continuum corrections. Evaluated on a 20% held-out sample, the model achieves noise-limited residuals over most of the spectral range and improves the signal-to-noise ratio of key diagnostic lines including [OII], H$β$, [OIII], and H$α$. The super-resolved spectra separate features that are entirely unresolved at prism resolution, such as the [OIII] $λ\lambda4959,5007$ doublet and H$β$, in exchange for a modest retrieval of line fluxes. As a proof of concept using JWST data, this approach is readily extensible to the low-resolution grism spectroscopy that will be delivered by Euclid and the Roman Space Telescope, potentially enabling population-level diagnostics across millions of galaxy spectra that would otherwise be inaccessible at low-resolution.

astro-ph.GA↗
arXiv2026

Little Red Dots are Direct-Collapse Black Hole-Forming Galaxies

"Little Red Dots" (LRDs) at $4 < z < 8$ are one of the most challenging discoveries by JWST to date because their distinctive V-shaped spectra and compact morphologies (100 - 200 pc) defy conventional astrophysical interpretation. Previous attempts to explain LRDs as compact stellar systems, heavily-cocooned black holes with differential flows, supermassive stars, or more exotic objects like 'black-hole stars' either cannot show how they formed, explain the origin of the dense shells needed for the absorption features in their spectra, or account for their observed abundances or inferred lifetimes. Here we show that LRDs are simply direct-collapse black hole galaxies in which the BH is still shrouded by the massive disk that created it. Our cosmological simulations yield spectra that are good matches to those of LRDs because high densities at the center of the disk trap X-rays from the BH and produce the observed Balmer absorption features while allowing UV, optical and reprocessed IR flux to partly escape. The host galaxy forms a dense 10$^8$ M$_{\odot}$ cluster of stars with a radius of 150 pc next to the BH, consistent with observations of LRDs. Our models reproduce a wide variety of LRD spectra from typical objects like RUBIES-EGS-42046 at $z = 5.28$ to those with the strongest Balmer breaks such as MoM-BH$^*$-1 at $z = 7.76$ and those at the highest redshifts like CAPERS-LRD-z9 at $z = 9.29$.

astro-ph.GA↗