3 Results

We find overwhelming odds against the hypothesis that all Type Ia supernovae produce gamma-ray bursts, whether at low redshift ($\ensuremath{\mathcal{O}}=10^{9}$:1) or high-redshift ($\ensuremath{\mathcal{O}}=10^{12}$:1). We also find large odds ($\ensuremath{\mathcal{O}}^\prime=34$:1) against the hypothesis that a fraction of Type Ia supernovae produce observable gamma-ray bursts.

We find very large odds ($\ensuremath{\mathcal{O}}=6000$:1) against the hypothesis that all Type Ib, Ib/c, and Ic supernovae produce observable gamma-ray bursts. We also find moderate odds ($\ensuremath{\mathcal{O}}^\prime=6$:1) against the hypothesis that a fraction of Type Ib-Ic supernovae produce observable bursts. If we nevertheless assume that this hypothesis is correct, we find that the fraction $f_{\rm SN}$ of Type Ib, Ib/c and Ic SNe that produce observable GRBs must be less than 0.17, 0.42, and 0.70 with 68%, 95%, and 99.6% probability, respectively. These limits are relatively weak because of the modest size (20 events) of our sample of Type Ib-Ic SNe.