Astronomy Tea Talk

  Strong emission line measurements of the gas phase metallicity of star forming galaxies are plagued by systematic uncertainties. In an effort to alleviate some of these problems we have developed IZI, a soon to be publicly available code that measures metallicities and ionization parameters given a set of emission line fluxes and an input photoionization model using Bayesian inference. The main advantage of IZI is that it removes the need of calibrating particular line ratio diagnostic while providing the user with flexibility to include an arbitrary set of emission line fluxes, errors (or upper limits) and model in the calculation. I will discuss the performance of commonly used abundance diagnostics in the context of IZI and the discrepancies seen in the abundance scale between empirically calibrated (i.e. using direct Te abundances) and theoretically calibrated strong emission line methods.