The Distribution Of Cosmological $\gamma$-ray Bursts

Abstract

We compare the burst distribution of the new (2B) BATSE catalogue to a cosmological distribution. The observed distribution agrees well with a cosmological one, however, it is insensitive to cosmological parameters such as \O and $\Lambda$. The bursts are not necessarily standard candles and their luminosity can vary by up to a factor of ten. The maximal red shift, \zm, of bursts longer than 2 sec is $2.1^{+1.}_{-.7}$ (assuming no evolution). The present data is insufficient to determine maximal red shift, \zm, of bursts shorter than 2 sec.Comment: 9 pages, uuencoded file, 4 figures included, can also be obtained from ftp://shemesh.fiz.huji.ac.il or at (Accepted for publication in the Astrophysical Journal Letters