Top: stellar mass vs. lifetime. Middle: stellar death rate after an initial “burst” forming 1 M_⊙ of stars: dN/ dt = dN/ dM × dM/ dt, where dN/ dM is the stellar IMF and dM/ dt the derivative of the curve in the top panel. The thick portion of the curve (up to ~35 My, corresponding to a star of 8 M_⊙) is the rate of CCSN. The bottom right part of the middle panel displays the corresponding SNIa rate (the time delay distribution or TDD) adopted in this work (thick curve); it is a mixture of the Greggio (2005) formulation for the SD scenario up to 4.5 Gyr and an extrapolation ∝ t^-1 after that time, in order to fit the data points from Maoz et al. (2012; filled circles) and from Maoz et al. (2010; squares). Bottom: time-integrated numbers of CCSN (thick portion of upper curve), single stars of mass M< 8M_⊙ (thin portion of upper curve) and SNIa (lower curve), as a function of time, for an initial “burst” of 1 M_⊙.