Since Hα, (FUV) and (TIR) luminosities were available for a complete galaxy sample, within a local 11 megaparsec volume, and the number of discovered supernovae in this sample is high enough to perform a meaningful comparison, the researchers exploited a multi-wavelength dataset from 11HUGS (11Mpc Hα UV Galaxy Survey). This volume-limited survey provided a census of SFR in the Local Volume.
There are a total of 14 supernovae discovered within this sample of galaxies and while this might not be complete, it provided a robust lower limit. The researchers assumed a lower limit of core collapse of 8 M⊙ (solar masses), which was proposed by direct detections of supernova progenitor stars and white dwarf progenitors. The CCSN rate matches the SFR for the FUV luminosity.
However, the SFR based on Hα luminosity is lower by two factors than those two estimates. This entails that the minimum mass for CCSN progenitors is 8 ± 1 M⊙ and 6 ± 1 M⊙, for FUV and Hαrespectively.
The conclusion is that the the minimum mass for CCSN progenitors is 8 ± 1 M⊙, on the lower mass limit, exploiting the FUV luminosity for the minimal constraint.