Large-scale homogeneity in the distribution of quasars in the Hercules-Corona Borealis Great Wall region

Abstract

In light of recent debates on the existence of a gigaparsec-scale structure traced by gamma-ray bursts, namely the Hercules-Corona Borealis Great Wall (HCBGW), we revisit large-scale homogeneity in the spatial distribution of quasars. Our volume-limited sample of quasars in the redshift range 1:6 < z ?2:1, which is constructed from the data release 7 of the Sloan Digital Sky Survey quasar catalogue, covers about half of the suspected HCBGW region. We analyze the sample in two complementary ways: fractal analysis of determining the average scale of homogeneity and friends- of-friends analysis of identifying specific large-scale structures. The quasar distribution on average reaches homogeneity at rh = 136?38h-1 Mpc and the richness and comoving size frequencies of large (>?150h-1 Mpc) quasar groups are consistent with the prediction of homogeneous distribution. These results put constraints on the spatial extent of the HCBGW but do not contradict its existence since our quasar sample does not cover the entire HCBGW region.