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

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Watson, Peter J., Davies, Roger L., van de Sande, Jesse, Brough, Sarah, Croom, Scott M., D'Eugenio, Francesco, Glazebrook, Karl, Groves, Brent, López-Sánchez, Ángel R., Scott, Nicholas, Vaughan, Sam P., Walcher, C Jakob, Bland-Hawthorn, Joss, Bryant, Julia J., Goodwin, Michael, Lawrence, Jon S., Lorente, Nuria P. F., Owers, Matt S., Richards, Samuel
• Other Authors: Swinburne University of Technology
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Oxford University Press (OUP) 2022
• Subjects: Lambda; sami
• Online Access: http://hdl.handle.net/1959.3/467472; https://doi.org/10.1093/mnras/stac1221

We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, lambda(Re), drawn from the SAMI Galaxy Survey. We fit a global [alpha/Fe]-sigma relation, finding that [alpha/Fe] = (0.395 +/- 0.010)log(10)(sigma) - (0.627 +/- 0.002). We observe an anti-correlation between the residuals Delta[alpha/Fe] and the inclination-corrected lambda(eo)(Re), which can be expressed as Delta[alpha/Fe] = (-0.057 +/- 0.008) lambda(eo)(Re) + (0.020 +/- 0.003). The anti-correlation appears to be driven by star-forming galaxies, with a gradient of Delta[alpha/Fe] similar to (-0.121 +/- 0.015) lambda(eo)(Re), 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 similar to 0.5 Gyr to (similar to)1.2 Gyr from low- to high-lambda(eo)(Re) Re galaxies. Slow rotators do not appear to fit these trends. Their residual a-enhancement is indistinguishable from other galaxies with lambda(eo)(Re) (sic) 0.4, despite being both larger and more massive. This result shows that galaxies with lambda(eo)(Re) (sic) 0.4 experience a similar range of star formation histories, despite their different physical structure and angular momentum.