Photometric metallicity map of the Small Magellanic Cloud [GA]

We have created an estimated metallicity map of the Small Magellanic Cloud (SMC) using the Magellanic Cloud Photometric Survey (MCPS) and Optical Gravitational Lensing Experiment (OGLE III) photometric data. This is a first of its kind map of metallicity up to a radius of $\sim$ 2.5$^{\circ}$. We identify the RGB in the V, (V$-$I) colour magnitude diagrams of small subregions of varying sizes in both data sets. We use the slope of the RGB as an indicator of the average metallicity of a subregion, and calibrate the RGB slope to metallicity using available spectroscopic data for selected subregions. The average metallicity of the SMC is found to be [Fe/H] = $-$0.94 dex ($\sigma$[Fe/H] = 0.09) from OGLE III, and [Fe/H] = $-$0.95 dex ($\sigma$[Fe/H] = 0.08) from MCPS. We confirm a shallow but significant metallicity gradient within the inner SMC up to a radius of 2.5$^{\circ}$ ($-$0.045$\pm$0.004 dex deg$^{-1}$ to $-$0.067$\pm$0.006 dex deg$^{-1}$).

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S. Choudhury, A. Subramaniam, A. Cole, et. al.
Thu, 11 Jan 18

Comments: 27 pages, 29 figures, Accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:1510.05769