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The history of stellar metallicity in a simulated disc galaxy

Snaith, O. N.; Bailin, J.; Gibson, B. K.; Bell, E. F.; Stinson, G.; Valluri, M.; Wadsley, J.; Couchman, H.; Gibson, Brad; Bailin, Jeremy; Bell, Eric; Couchman, Hugh; Snaith, Owain; Stinson, Gregory; Valluri, Monica; Wadsley, James

Authors

O. N. Snaith

J. Bailin

E. F. Bell

G. Stinson

M. Valluri

J. Wadsley

H. Couchman

Jeremy Bailin

Eric Bell

Hugh Couchman

Owain Snaith

Gregory Stinson

Monica Valluri

James Wadsley



Abstract

We explore the chemical distribution of stars in a simulated galaxy. Using simulations of the same initial conditions but with two different feedback schemes (McMaster Unbiased Galaxy Simulations – MUGS – and Making Galaxies in a Cosmological Context – MaGICC), we examine the features of the age–metallicity relation (AMR), and the three-dimensional age– [Fe/H]–[O/Fe] distribution, both for the galaxy as a whole and decomposed into disc, bulge, halo and satellites. The MUGS simulation, which uses traditional supernova feedback, is replete with chemical substructure. This substructure is absent from the MaGICC simulation, which includes early feedback from stellar winds, a modified initial mass function and more efficient feedback. The reduced amount of substructure is due to the almost complete lack of satellites in MaGICC. We identify a significant separation between the bulge and disc AMRs, where the bulge is considerably more metal-rich with a smaller spread in metallicity at any given time than the disc. Our results suggest, however, that identifying the substructure in observations will require exquisite age resolution, of the order of 0.25 Gyr. Certain satellites show exotic features in the AMR, even forming a ‘sawtooth’ shape of increasing metallicity followed by sharp declines which correspond to pericentric passages. This fact, along with the large spread in stellar age at a given metallicity, compromises the use of metallicity as an age indicator, although alpha abundance provides a more robust clock at early times. This may also impact algorithms that are used to reconstruct star formation histories from resolved stellar populations, which frequently assume a monotonically increasing AMR.

Publication Date Mar 1, 2016
Journal Monthly notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press (OUP)
Peer Reviewed Peer Reviewed
Volume 456
Issue 3
Pages 3119-3141
Institution Citation Snaith, O. N., Bailin, J., Gibson, B. K., Bell, E. F., Stinson, G., Valluri, M., …Couchman, H. (2016). The history of stellar metallicity in a simulated disc galaxy. Monthly notices, containing papers, abstracts of papers, and reports of the proceedings of the Society, 456(3), 3119-3141. https://doi.org/10.1093/mnras/stv2788
DOI https://doi.org/10.1093/mnras/stv2788
Keywords Methods -- numerical, Galaxies -- abundances, Galaxies -- evolution, Galaxies -- general
Publisher URL http://mnras.oxfordjournals.org/content/456/3/3119
Copyright Statement © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society
Additional Information Copy of article first published in: Monthly notices of the Royal Astronomical Society, 2016, v.456, issue 3

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Copyright Statement
© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society





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