Observational [O/Fe]–sSFR relation compared with a range of model relations. Data points (big circles) were shifted to a common intermediate [O/Fe] baseline with additional offset due to possible oxygen dust depletion (Δ_d) included (see Figure 8 and Section 5). Dark coloured ranges show the [O/Fe]–sSFR relations calculated with 1 for different SN Ia DTD and parameter choices. Left panel: power-law DTD with the minimum SN Ia delay time τ_Ia; min = 100 Myr and different slopes α_Ia. Right panel: analytic DTD for mixed single degenerate and double degenerate SN Ia scenario from Greggio (2005, 2010), as used by Kashino et al. (2022). The coloured ranges span between the relations calculated with C_Ia/CC = 0.74 (upper edges) and C_Ia/CC = 2.5 (bottom edges) – see text for the details. We also plot the relations followed by TNG100-1-like galaxies (brown line, left panel) and the relation from Kashino et al. (2022) (black dotted line, right panel).