Protecting Life in the Milky Way: Metals Keep the GRBs Away

The host galaxies of the four local, z<0.17, long-duration gamma-ray bursts, each of which had an associated hypernova studied with optical spectroscopy, are all faint and metal-poor compared to the population of local star-forming galaxies. We quantify this statement by using a previous analysis of star-forming galaxies (z<0.2) from the Sloan Digital Sky Survey to estimate the fraction of local star formation as a function of host galaxy oxygen abundance. We find that only a small fraction (<20%) of current star formation occurs in galaxies with oxygen abundance 12+log(O/H)