Typical emission line diagnostic diagrams for the analysis of ionization sources. The data points are the population of bins with Hα flux ≥5σ, colored by their η′ value. The black dotted line marks the theoretical limit for starburst galaxies from Kewley et al. (2001). The solid and dashed lines mark the metallicity (Z) and ionization parameter (q) grid of photoionization models described in Levesque et al. (2010) for the best-fitting star formation age of 0 Myr and electron density of 100 cm⁻³.