Anomalies in the GRB spatial distribution

Abstract

Swift's remarkable ability to quickly localize gamma-ray bursts has led to the accumulation of a sizable burst sample for which both angular locations and redshifts are measured. This sample has become large enough that it can potentially be used to probe angular anisotropies indicative of large-scale universal structure. In a previous work, a large clustering of gamma-ray bursts at redshift z ≈ 2 was reported in the general direction of the constellations of Hercules and Corona Borealis. Since that report, a 42% increase in the number of z ≈ 2 gamma-ray bursts has been observed, warranting an updated analysis. Surprisingly, the cluster is more pronounced now than it was when it was first reported.