The Metallicity Dilution in Local Massive Early-type Galaxies

We derive a sample of 114 Baldwin–Phillips–Terlevich-diagram star-forming and Wide-field Infrared Survey Explorer (WISE) low-star-formation-rate early-type galaxies (ETGs) by utilizing the criterion W2 − W3 < 2.5 (where W2 and W3 are the wavelengths of 4.6 and 12 μ m in the WISE four bands) and c...

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Bibliographic Details
Published in:The Astronomical journal 2024-11, Vol.168 (5), p.226
Main Authors: Wu, Yu-zhong, Zhang, Wei
Format: Article
Language:English
Subjects:
Astrophysics
Dilution
Early-type galaxies
Emission measurements
Galaxies
Galaxy abundances
Infrared astronomy
Intergalactic media
Metallicity
Sky surveys (astronomy)
Star formation
Stars
Wavelengths
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Summary:We derive a sample of 114 Baldwin–Phillips–Terlevich-diagram star-forming and Wide-field Infrared Survey Explorer (WISE) low-star-formation-rate early-type galaxies (ETGs) by utilizing the criterion W2 − W3 < 2.5 (where W2 and W3 are the wavelengths of 4.6 and 12 μ m in the WISE four bands) and cross matching the Galaxy Zoo 1 and the catalog of the Sloan Digital Sky Survey (SDSS) Data Release 7 Max Planck Institute for Astrophysics-Johns Hopkins University emission-line measurements. We find that ∼28% of our ETGs exhibit a metallicity that is at least 2 standard deviation (0.26 dex) below the mass–metallicity (MZ) relation of star-forming galaxies (SFGs) from the SDSS. We demonstrate that almost all of our ETGs locate below the “main sequence” of SFGs. We find that these ETGs with larger metallicity deviation from the MZ relation tend to have lower SFR and redder color. By exploring the dilution properties of these massive ETGs, we report that the dilution effect may be mainly attributed to the inflow of metal-poor gas from mergers/interaction or the intergalactic medium.
ISSN:0004-6256
1538-3881
DOI:10.3847/1538-3881/ad7e1e