log $t_g$ reported in @Gallazzi:2005df in order to weight the galaxy population with the DTD at fixed mass (rather than using only the median value). These should alleviate the effect of average ages by giving greater weight to the low-age tail of their derived distribution and by allowing for a non-negligible rate of star formation today, particularly for lower-mass galaxies, that is in rough agreement with the specific star formation rates measured by @Schiminovich:2007kw.

This leaves the issue of the efficiency of converting a stellar population into SNe Ia (see, e.g., @Maoz:2007xw). As we will discuss in Section \[section:iv\], the DTD is also involved in shaping the cosmic SN Ia history, with $\phi_*$ again setting the overall normalization. Rather than attempting to incorporate theoretical models of the DTD (see, e.g., @Greggio:2010en), we use a DTD with a pure power law of the form $\Delta t^{-\gamma}$, with a lower cutoff $t_c$ to account for the minimum amount of time needed to produce CO WDs. Evidence for delay times as short as $\lesssim\,$100 Myr has been reported from, e.g., the study of SN remnants in the Magellanic Clouds [@Badenes:2009bs; @Maoz:2010pz], and we simply use $t_c=50$ Myr (see also the discussion in Section 