A new constraint for gamma-ray burst progenitor mass

Recent comparative observations of long-duration gamma-ray bursts (LGRBs) and core collapse supernova (cc SN) host galaxies demonstrate that these two, highly energetic transient events are distributed very differently upon their hosts. LGRBs are much more concentrated on their host galaxy light than cc SN. Here we explore the suggestion that this differing distribution reflects different progenitor masses for LGRBs and cc SN. Using a simple model we show that, assuming cc SN arise from stars with main-sequence masses > 8 M-circle dot, GRBs are likely to arise from stars with initial masses > 20 M-circle dot. This difference can naturally be explained by the requirement that stars which create a LGRB must also create a black hole