Classic diagnostic diagrams based on emission line ratios (Baldwin et al. 1981; Veilleux & Osterbrock 1987): [O III]λ5007/Hβ vs. [NII]λ6584/Hα (top) and [O III]λ5007/ Hβ vs. [S II]λλ6716.6731/Hα (bottom). Symbols show the emission-line–integrated fluxes (gray squares) and narrow (blue circles) and broad (red circles) Gaussian components for each galaxy. The gray dots correspond to the SDSS-DR7 MPA-JHU galaxy sample from Pérez-Montero et al. (2021). Regions of different excitation mechanisms are labeled and established by the theoretical and empirical demarcation lines of Kewley et al.; Kewley et al. (2001; 2006, dashed black), Kauffmann et al. (2003, dashed gray), and Schawinski et al. (2007), solid brown).