SAMI Galaxy Survey: Spatially resolved metallicity and ionization mapping

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Poetrodjojo, Henry, Groves, Brent, Kewley, Lisa J., Medling, Anne M., Sweet, Sarah M., van de Sande, Jesse, Sanchez, Sebastian F., Bland-Hawthorn, Joss, Brough, Sarah, Bryant, Julia J., Cortese, Luca, Croom, Scott M., López-Sánchez, Ãngel R., Richards, Samuel N., Zafar, Tayyaba, Lawrence, Jon S., Lorente, Nuria P. F., Owers, Matt S., Scott, Nicholas
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Royal Astronomical Society 2018
• Subjects: galaxies: abundances – galaxies: ISM; sami
• Online Access: https://doi.org/10.1093/mnras/sty1782

We present gas-phase metallicity and ionization parameter maps of 25 star-forming face-on spiral galaxies from the SAMI Galaxy Survey Data Release 1. Self-consistent metallicity and ionization parameter maps are calculated simultaneously through an iterative process to account for the interdependence of the strong emission line diagnostics involving ([O II]+[O III])/Hβ (R_(23)) and [O III]/[O II](O32). The maps are created on a spaxel-by-spaxel basis because H II regions are not resolved at the SAMI spatial resolution. We combine the SAMI data with stellar mass, star formation rate (SFR), effective radius (R_e), ellipticity, and position angles (PA) from the GAMA survey to analyse their relation to the metallicity and ionization parameter. We find a weak trend of steepening metallicity gradient with galaxy stellar mass, with values ranging from −0.03 to −0.20 dex/R_e. Only two galaxies show radial gradients in the ionization parameter. We find that the ionization parameter has no significant correlation with either SFR, sSFR (specific SFR), or metallicity. For several individual galaxies, we find the structure in the ionization parameter maps suggestive of spiral arm features. We find a typical ionization parameter range of 7.0 < log (q) < 7.8 for our galaxy sample with no significant overall structure. An ionization parameter range of this magnitude is large enough to caution the use of metallicity diagnostics that have not considered the effects of a varying ionization parameter distribution. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices). Accepted 2018 July 3. Received 2018 July 1; in original form 2018 April 5. Published: 05 July 2018. The SAMI Galaxy Survey is based on observations made at the Anglo-Australian Telescope. The Sydney-AAO ...