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The origin of the α-enhancement of massive galaxies

Segers, M.C.; Schaye, J.; Bower, R.G.; Crain, R.A.; Schaller, M.; Theuns, T.

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Authors

M.C. Segers

J. Schaye

R.G. Bower

R.A. Crain

M. Schaller



Abstract

We study the origin of the stellar α-element-to-iron abundance ratio, [α/Fe]*, of present-day central galaxies, using cosmological, hydrodynamical simulations from the Evolution and Assembly of GaLaxies and their Environments (EAGLE) project. For galaxies with stellar masses of M* > 1010.5 M⊙, [α/Fe]* increases with increasing galaxy stellar mass and age. These trends are in good agreement with observations of early-type galaxies, and are consistent with a ‘downsizing’ galaxy formation scenario: more massive galaxies have formed the bulk of their stars earlier and more rapidly, hence from an interstellar medium that was mostly α-enriched by massive stars. In the absence of feedback from active galactic nuclei (AGNs), however, [α/Fe]* in M* > 1010.5 M⊙ galaxies is roughly constant with stellar mass and decreases with mean stellar age, extending the trends found for lower mass galaxies in both simulations with and without AGN. We conclude that AGN feedback can account for the α-enhancement of massive galaxies, as it suppresses their star formation, quenching more massive galaxies at earlier times, thereby preventing the iron from longer lived intermediate-mass stars (supernova Type Ia) from being incorporated into younger stars.

Citation

Segers, M., Schaye, J., Bower, R., Crain, R., Schaller, M., & Theuns, T. (2016). The origin of the α-enhancement of massive galaxies. Monthly Notices of the Royal Astronomical Society: Letters, 461(1), L102-L106. https://doi.org/10.1093/mnrasl/slw111

Journal Article Type Article
Acceptance Date May 25, 2016
Online Publication Date May 27, 2016
Publication Date Sep 1, 2016
Deposit Date Aug 18, 2016
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society: Letters
Electronic ISSN 1745-3933
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 461
Issue 1
Pages L102-L106
DOI https://doi.org/10.1093/mnrasl/slw111

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Copyright Statement
This article has been published in Monthly Notices of the Royal Astronomical Society: Letters ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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