Non-homogeneities in the spatial distribution of gamma-ray bursts

Abstract

In order to reveal possible non-homogeneities in the spatial distribution of long (T_90 > 2^s) gamma-ray bursts we have examined 201 of them with known redshifts z. For different functional forms of metric distance r(z)we use the distribution function f(l)of separations between objects. Asymptotically, for small l this function behaves like f(l)~l^{D-1} for fractal sets whose fractal dimension is D. It is revealed that for all of the considered forms of r(z) the spatial distribution of gamma-ray burst sources shows signs of fractality with D=2.2-2.5. A few spatially isolated groups of gamma-ray burst sources have been found, one of which has equatorial coordinates alpha extending from 23^h 56^m to 0^h 49^m and delta from +19^o to +23^o its redshifts being within the range of 0.81 to 0.94.