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

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.

Automated summary

We explore the relationship between the mean stellar population properties and the spin parameter proxy in a sample of 1492 galaxies. We find that there is a correlation between the two, with disc-dominated galaxies having an extended duration of star formation.