The SAMI Galaxy Survey: the link between [α/Fe] and kinematic morphology

Peter J. Watson*, Roger L. Davies, Jesse van de Sande, Sarah Brough, Scott M. Croom, Francesco D'Eugenio, Karl Glazebrook, Brent Groves, Ángel R. López-Sánchez, Nicholas Scott, Sam P. Vaughan, C. Jakob Walcher, Joss Bland-Hawthorn, Julia J. Bryant, Michael Goodwin, Jon S. Lawrence, Nuria P. F. Lorente, Matt S. Owers, Samuel Richards

*Corresponding author for this work

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Abstract

We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, λRe⁠, drawn from the SAMI Galaxy Survey. We fit a global [α/Fe]–σ relation, finding that [α/Fe]=(0.395±0.010)log10(σ)−(0.627±0.002)⁠. We observe an anti-correlation between the residuals Δ[α/Fe] and the inclination-corrected λeoRe⁠, which can be expressed as Δ[α/Fe]=(−0.057±0.008)λeoRe+(0.020±0.003)⁠. The anti-correlation appears to be driven by star-forming galaxies, with a gradient of Δ[α/Fe]∼(−0.121±0.015)λeoRe⁠, although a weak relationship persists for the subsample of galaxies for which star formation has been quenched. We take this to be confirmation that disc-dominated galaxies have an extended duration of star formation. At a reference velocity dispersion of 200 km s−1, we estimate an increase in half-mass formation time from ∼0.5 Gyr to ∼1.2 Gyr from low- to high-λeoRe galaxies. Slow rotators do not appear to fit these trends. Their residual α-enhancement is indistinguishable from other galaxies with λeoRe⪅0.4⁠, despite being both larger and more massive. This result shows that galaxies with λeoRe⪅0.4 experience a similar range of star formation histories, despite their different physical structure and angular momentum.
Original languageEnglish
Pages (from-to)5076-5087
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume513
Issue number4
DOIs
Publication statusPublished - Jul 2022

Bibliographical note

Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • galaxies: evolution
  • galaxies: formation
  • galaxies: kinematics and dynamics
  • galaxies: stellar content

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