The gas-phase metallicities of star-forming galaxies in aperture-matched SDSS samples follow potential rather than mass or average surface density

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: D'Eugenio, Francesco, Colless, Matthew, Groves, Brent, Bian, Fuyan, Barone, Tania
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press
• Subjects: sami
• Online Access: http://hdl.handle.net/1885/197995; https://doi.org/10.1093/mnras/sty1424; https://openresearch-repository.anu.edu.au/bitstream/1885/197995/5/01_D%2527Eugenio_The_gas-phase_metallicities_of_2018.pdf.jpg

We present a comparative study of the relation between the aperture-based gas-phase metallicity and three structural parameters of star-forming galaxies: mass (M = M*), average potential (Φ=M*/Re), and average surface mass density (ε = M*/R2 e, where Re is the effective radius). We use a volume-limited sample drawn from the publicly available SDSS DR7, and base our analysis on aperture-matched sampling by selecting sets of galaxies where the SDSS fibre probes a fixed fraction of Re. We find that between 0.5 and 1.5 Re, the gas-phase metallicity correlates more tightly with Φ than with either M* or ε in that for all aperture-matched samples, the potential-metallicity relation has (i) less scatter, (ii) higher Spearman rank correlation coefficient, and (iii) less residual trend with Re than either themass-metallicity relation and the average surface density-metallicity relation. Our result is broadly consistent with the current models of gas enrichment and metal loss. However, amore natural explanation for our findings is a local relation between the gas-phase metallicity and the escape velocity. FDE acknowledges useful discussion with Prof. Roger L. Davies, Dr. Luca Cortese, Prof. Andrea Maccio, Dr. Chiaki Kobayashi, Dr. ` Philip Taylor, Dilyar Barat, and with the members of the SAMI Galaxy Survey team. TMB is supported by an Australian Government Research Training Program Scholarship. Parts of this research were supported by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO; grant CE110001020), and the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D; grant CE170100013). BG gratefully acknowledges the support of the Australian Research Council as the recipient of a Future Fellowship (FT140101202). Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space ...