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
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: galaxies: evolution; galaxies: formation; galaxies: kinematics and dynamics; galaxies: stellar content; sami
• Online Access: https://researchers.mq.edu.au/en/publications/fef4a354-9ecf-4bba-9edb-898df7fba8e2; https://doi.org/10.1093/mnras/stac1221; https://research-management.mq.edu.au/ws/files/216026824/213452055.pdf; http://www.scopus.com/inward/record.url?scp=85133139210&partnerID=8YFLogxK; http://purl.org/au-research/grants/arc/CE170100013; http://purl.org/au-research/grants/arc/CE110001020; http://purl.org/au-research/grants/arc/DE200100461; http://purl.org/au-research/grants/arc/FT140101166; http://purl.org/au-research/grants/arc/FT140101202; http://purl.org/au-research/grants/arc/DE190100375; http://purl.org/au-research/grants/arc/FL140100278; http://purl.org/au-research/grants/arc/LE130100198; http://purl.org/au-research/grants/arc/FT180100231; http://purl.org/au-research/grants/arc/FT140100255

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