The Effects of Diffuse Ionized Gas and Spatial Resolution on Metallicity
  Gradients: TYPHOON Two-Dimensional Spectrophotometry of M83
  We present a systematic study of the diffuse ionized gas (DIG) in M83 and its
effects on the measurement of metallicity gradients at varying resolution
scales. Using spectrophotometric data cubes of M83 obtained at the 2.5m duPont
telescope at Las Campanas Observatory as part of the TYPHOON program, we
separate the HII regions from the DIG using the [SII]/H$\alpha$ ratio, HIIphot
(HII finding algorithm) and the H$\alpha$ surface brightness. We find that the
contribution to the overall H$\alpha$ luminosity is approximately equal for the
HII and DIG regions. The data is then rebinned to simulate low-resolution
observations at varying resolution scales from 41 pc up to 1005 pc. Metallicity
gradients are measured using five different metallicity diagnostics at each
resolution. We find that all metallicity diagnostics used are affected by the
inclusion of DIG to varying degrees. We discuss the reasons of why the
metallicity gradients are significantly affected by DIG using the HII dominance
and emission line ratio radial profiles. We find that applying the
[SII]/H$\alpha$ cut will provide a closer estimate of the true metallicity
gradient up to a resolution of 1005 pc for all metallicity diagnostics used in
this study.
