An intrinsic anisotropy in the angular distribution of gamma-ray bursts

The anisotropy of the sky distribution of 2025 gamma-ray bursts (GRBs) coll ected in Current BATSE catalog is confirmed. It is shown that the quadrupol e term being proportional to similar to sin 2b sin I is non-zero with a pro bability 99.9%. The occurrence of this anisotropy term is then supported by the binomial test even with the probability 99.97%. It is also argued that this anisotropy cannot be caused exclusively by instrumental effects due t o the non-uniform sky exposure of BATSE instrument; there should exist also some intrinsic anisotropy in the angular distribution of GRBs. Separating GRBs into short and long subclasses, it is shown that the 251 short ones ar e distributed anisotropically, but the 681 long ones seem to be distributed still isotropically. The 2-sample Kolmogorov Smirnov test shows that they are distributed differently with a 98.7% probability. The character of anis otropy suggests that the cosmological origin of short GRBs further holds, a nd there is no evidence for their Galactical origin. The work in essence co ntains the key ideas and results of a recently published paper (Balazs et a l. 1998), to which the new result following from the 2-sample Kolmogorov-Sm irnov test is added, too.