Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts
Recent stellar chemical abundance measurements of a handful of z ∼ 2 quiescent galaxies have suggested these galaxies exhibit a remarkably strong α -enhancement compared to their local and intermediate-redshift counterparts. This apparent chemical evolution following quenching suggests that even the...
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2025-01-01
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| author | Marziye Jafariyazani Andrew B. Newman Bahram Mobasher Sirio Belli Richard S. Ellis Andreas L. Faisst |
| author_facet | Marziye Jafariyazani Andrew B. Newman Bahram Mobasher Sirio Belli Richard S. Ellis Andreas L. Faisst |
| author_sort | Marziye Jafariyazani |
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| description | Recent stellar chemical abundance measurements of a handful of z ∼ 2 quiescent galaxies have suggested these galaxies exhibit a remarkably strong α -enhancement compared to their local and intermediate-redshift counterparts. This apparent chemical evolution following quenching suggests that even the innermost regions of massive early-type galaxies may have experienced substantial mixing of stars in mergers, challenging a purely inside-out growth model. However, larger samples are needed to determine whether a high α -enhancement ([Mg/Fe] ≈0.5) is common in z ∼ 2 quiescent galaxies, and a comparative analysis is needed to determine whether it is consistently inferred using different stellar population synthesis models. We report age and stellar chemical abundance measurements for a sample of four gravitationally lensed quiescent galaxies at z ∼ 2.1–2.65 based on Magellan/FIRE spectroscopy. For three of these galaxies we constrain the α -enhancement, and in two cases we measure high values comparable to earlier results when the spectra are analyzed consistently. We also find that the choice of modeling approach can exert a significant effect on the measured abundances. This model dependence can be partly, but not entirely, explained by the complex abundance patterns of α -elements in galaxies, which has been observed at lower redshifts and in one z ∼ 2 quiescent galaxy. Our investigation highlights the importance of independently varying abundance of α -elements when fitting the spectra of such galaxies. Observations with JWST will soon deliver precise and spatially resolved abundances of these and other quiescent galaxies at cosmic noon, opening a new window into their evolution. |
| format | Article |
| id | doaj-art-b6f600939e84412d8d07db511e6c98ff |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-b6f600939e84412d8d07db511e6c98ff2025-08-20T03:45:34ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01986214810.3847/1538-4357/addbdcChemical Abundances of Early Quiescent Galaxies: New Observations and Modeling ImpactsMarziye Jafariyazani0https://orcid.org/0000-0001-8019-6661Andrew B. Newman1https://orcid.org/0000-0001-7769-8660Bahram Mobasher2https://orcid.org/0000-0001-5846-4404Sirio Belli3https://orcid.org/0000-0002-5615-6018Richard S. Ellis4https://orcid.org/0000-0001-7782-7071Andreas L. Faisst5https://orcid.org/0000-0002-9382-9832SETI Institute , Mountain View, CA, USA; Carnegie Science Observatories , Pasadena, CA, USA; Department of Physics and Astronomy, University of California , Riverside, CA, USACarnegie Science Observatories , Pasadena, CA, USADepartment of Physics and Astronomy, University of California , Riverside, CA, USADipartimento di Fisica e Astronomia, Università di Bologna , Bologna, ItalyDepartment of Physics and Astronomy, University College London , Gower Street, London WC1E 6BT, UKCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USARecent stellar chemical abundance measurements of a handful of z ∼ 2 quiescent galaxies have suggested these galaxies exhibit a remarkably strong α -enhancement compared to their local and intermediate-redshift counterparts. This apparent chemical evolution following quenching suggests that even the innermost regions of massive early-type galaxies may have experienced substantial mixing of stars in mergers, challenging a purely inside-out growth model. However, larger samples are needed to determine whether a high α -enhancement ([Mg/Fe] ≈0.5) is common in z ∼ 2 quiescent galaxies, and a comparative analysis is needed to determine whether it is consistently inferred using different stellar population synthesis models. We report age and stellar chemical abundance measurements for a sample of four gravitationally lensed quiescent galaxies at z ∼ 2.1–2.65 based on Magellan/FIRE spectroscopy. For three of these galaxies we constrain the α -enhancement, and in two cases we measure high values comparable to earlier results when the spectra are analyzed consistently. We also find that the choice of modeling approach can exert a significant effect on the measured abundances. This model dependence can be partly, but not entirely, explained by the complex abundance patterns of α -elements in galaxies, which has been observed at lower redshifts and in one z ∼ 2 quiescent galaxy. Our investigation highlights the importance of independently varying abundance of α -elements when fitting the spectra of such galaxies. Observations with JWST will soon deliver precise and spatially resolved abundances of these and other quiescent galaxies at cosmic noon, opening a new window into their evolution.https://doi.org/10.3847/1538-4357/addbdcChemical abundancesGalaxy chemical evolutionAbundance ratiosMetallicityEarly-type galaxiesGalaxy quenching |
| spellingShingle | Marziye Jafariyazani Andrew B. Newman Bahram Mobasher Sirio Belli Richard S. Ellis Andreas L. Faisst Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts The Astrophysical Journal Chemical abundances Galaxy chemical evolution Abundance ratios Metallicity Early-type galaxies Galaxy quenching |
| title | Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts |
| title_full | Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts |
| title_fullStr | Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts |
| title_full_unstemmed | Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts |
| title_short | Chemical Abundances of Early Quiescent Galaxies: New Observations and Modeling Impacts |
| title_sort | chemical abundances of early quiescent galaxies new observations and modeling impacts |
| topic | Chemical abundances Galaxy chemical evolution Abundance ratios Metallicity Early-type galaxies Galaxy quenching |
| url | https://doi.org/10.3847/1538-4357/addbdc |
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