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Abstract Understanding the chemical enrichment of different elements is crucial to gaining a complete picture of galaxy chemical evolution. In this study, we present a new sample of 46 low-redshift, low-mass star-forming galaxies atM*∼ 108−10M⊙along with two quiescent galaxies atM*∼ 108.8M⊙observed with the Keck Cosmic Web Imager, aiming to investigate the chemical evolution of galaxies in the transition zone between Local Group satellites and massive field galaxies. We develop a novel method to simultaneously determine stellar abundances of iron and magnesium in star-forming galaxies. With the gas-phase oxygen abundance (O/H)gmeasured using the strong-line method, we are able to make the first-ever apples-to-apples comparison ofαelements in the stars and the interstellar medium. We find that the [Mg/H]*–[O/H]grelation is much tighter than the [Fe/H]*–[O/H]grelation, which can be explained by the similar production processes ofαelements. Most galaxies in our sample exhibit higher [O/H]gthan [Fe/H]*and [Mg/H]*. In addition, we construct mass–metallicity relations (MZRs) measured as three different elements (Fe*, Mg*, Og). Compared to the gas O-MZR, the stellar Fe- and Mg-MZRs show larger scatter driven by variations in specific star formation rates (sSFR), with star-forming galaxies exhibiting higher sSFR and lower stellar abundances at fixed mass. The excess of [O/H]gcompared to stellar abundances as well as the anticorrelation between sSFR and stellar abundance suggests that galaxy quenching of intermediate-mass galaxies atM*∼ 108−10M⊙is primarily driven by starvation.
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Chemo-dynamical Evolution of Simulated Satellites for a Milky Way–like Galaxy
Abstract The chemical abundances of Milky Way’s (MW's) satellites reflect their star formation histories (SFHs), yet, due to the difficulty of determining the ages of old stars, the SFHs of most satellites are poorly measured. Ongoing and upcoming surveys will obtain around 10 times more medium-resolution spectra for stars in satellites than are currently available. To correctly extract SFHs from large samples of chemical abundances, the relationship between chemical abundances and SFHs needs to be clarified. Here, we perform a high-resolution cosmological zoom-in simulation of a MW-like galaxy with detailed models of star formation, supernova (SN) feedback, and metal diffusion. We quantify SFHs, metallicity distribution functions, and theα-element (Mg, Ca, and Si) abundances in satellites of the host galaxy. We find that star formation in most simulated satellites is quenched before infalling to their host. Star formation episodes in simulated satellites are separated by a few hundred Myr owing to SN feedback; each star formation event produces groups of stars with similar [α/Fe] and [Fe/H]. We then perform a mock observation of the upcoming Subaru Prime Focus Spectrograph (PFS) observations. We find that Subaru PFS will be able to detect distinct groups of stars in [α/Fe] versus [Fe/H] space, produced by episodic star formation. This result means that episodic SFHs can be estimated from the chemical abundances of ≳1000 stars determined with medium-resolution spectroscopy.
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- PAR ID:
- 10543328
- Publisher / Repository:
- NASA ADS
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 970
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 105
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3847/1538-4357/ad500c
