Observational biases in SEL metallicity measurements of extragalactic H II regions

Measuring the chemical composition of the ISM in galaxies holds significant importance in astrophysics, as it influences stellar, galaxy, and cosmological evolution. According to the baryon cycle, the abundance of heavy elements should consistently rise over cosmic time, linking the metallicity of a galaxy to its evolutionary stage. Indeed, researchers have identified several relationships between metallicity and other galaxies’ parameters, such as mass and luminosity. We are reaching the moment where inaccurate metallicity measurements are becoming the limiting factors in extragalactic studies, in particular when comparing observations with simulations. Our study aims to investigate potential observational biases in the strong emission line methods used to estimate metallicities in nearby galaxies, focusing our attention on estimating the relevance of the DIG contamination and the influence of the aperture’s size in the computation.