From top to bottom: log  ([O iii]/Hβ), log  ([N ii]/Hα), log  (EW(Hα)), and log  (τ) vs normalized photometric radius R^⋆/r_p. The gray shaded areas in panels a&b mark the mean and ± 1σ of the respective quantity, and in panel c the mean EW(Hα) for R^⋆ ≥ r_p (0.43 ± 0.65 Å). The light-blue area in panel c depicts the range in EW(Hα) that can be accounted for by pAGB photoionization models (0.1–2.4 Å). The color assigned to each ETG is related to its ⟨τ⟩ (cf. text and Fig. 3) in ascending order, from orange to violet, and is identical in all figures.