Observational evidence for a correlation between peak - luminosities and beaming in GRBs
نویسنده
چکیده
We calculate the unseen-but-true GRB-event rate from a current flux-limited sample of 33 GRBs with individually measured redshifts. We consider a GRBevent rate which is proportional to the star-formation rate, in view of the GRBSNe association in SN1998bw and GRB030329. By fitting a log-normal distribution of GRB peak-luminosities, we find a ratio 1/fr ≃ 450 for the true-to-observed GRB-event rates. This provides an independent derivation of the GRB-beaming factor 1/fb ≃ 500 obtained by Frail et al. (2001) from sources with standard GRB-energies. We discuss applications to GRB980425. Subject headings: gamma-rays: bursts, beaming
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