New data support the existence of the Hercules-Corona Borealis Great Wall

Abstract

Context. Several large structures, including the Sloan Great Wall, the Huge Large Quasar Group, and a large gamma-ray burst cluster referred to as the Hercules-Corona Borealis Great Wall, appear to exceed the maximum structural size predicted by Universal inflationary models. The existence of very large structures such as these might necessitate cosmological model modifications. Aims. Gamma-ray bursts are the most luminous sources found in nature. They are associated with the stellar endpoints of massive stars and are found in and near distant galaxies. Since they are viable indicators of the dense part of the Universe containing normal matter, the spatial distribution of gamma-ray bursts can serve as tracers of Universal large-scale structure.Methods. An increased sample size of gamma-ray bursts with known redshift provides us with the opportunity to validate or invalidate the existence of the Hercules-Corona Borealis Great Wall. Nearest-neighbour tests are used to search the larger sample for evidence of clustering and a bootstrap point-radius method is used to estimate the angular cluster size. The potential influence of angular sampling biasing is studied to determine the viability of the results. Results. The larger gamma-ray burst database further supports the existence of a statistically significant gamma-ray burst cluster at 1.6 ≤ z < 2.1 with an estimated angular size of 2000-3000 Mpc. Conclusions. Although small number statistics limit our angular resolution and do not rule out the existence of adjacent and/or lineof-sight smaller structures, these structures must still clump together in order for us to see the large gamma-ray burst cluster detected here. This cluster provides support for the existence of very large-scale universal heterogeneities.Key words. gamma rays: general -methods: data analysis -methods: statistical -large-scale structure of Universecosmology: observations -distance scale IntroductionThe high luminosities of gamma-ray bursts (GRBs) make them ideal candidates for probing large-scale Universal structure. Gamma-ray bursts signify the presence of stellar endpoints and thus trace the location of matter in the universe. This is true whether they are long bursts (presumably originating from hypernovae), short bursts (presumably originating from compact objects), or intermediate bursts (with unknown origins that are still likely related to stellar endpoints). Assuming that the Universe is homogeneous and isotropic on a large scale implies that the large-scale distribution of GRBs should similarly be homogeneous and isotropic. The angular isotropy of GRBs has been well-studied over the past few decades (Briggs et al. 1996;Balázs et al. 1998Balázs et al. , 1999Mészáros et al. 2000;Magliocchetti et al. 2003;Vavrek et al. 2008). For the most part, GRBs are distributed uniformly, although some subsamples (generally believed to be those with lower luminosities and therefore thought to be cosmologically local) appear to deviate from isotropy (Balázs et al. 1998;Cline et al. 1999;Mészár...

Testing the Isotropic Universe Using the Gamma-Ray Burst Data of Fermi/GBM

“…Both areas are in the same quadrant on the sky and they partially overlap. This finding is also interesting considering that Horváth et al (2014); Horváth et al (2015) used completely different approach and they studied number densities of GRBs on the sky for various redshift intervals employing a data set from a different satellite.…”

“…Recently, Horváth et al (2014); Horváth et al (2015) studied the spatial distribution of GRBs taking into account their redshift. They concluded that there was a statistically significant clustering of GRBs at redshift 1.6 < z ≤ 2.1 and that the size of the structure defined by these GRBs was about 2 000-3 000 Mpc, so called Hercules-Corona Borealis Great Wall.…”

“…Another question is if the Galactical gas and dust absorption can affect our results. Horváth et al (2014); Horváth et al (2015) studied the spatial distribution of GRBs, detected by Swift satellite (Gehrels et al 2004), taking into account their redshift z. They used a two-dimensional KolmogorovSmirnov test, a nearest-neighbour test, and a bootstrap point-radius method applied on several sub-samples of different redshift intervals.…”

“…They concluded that there was a statistically significant clustering of the GRB sample at 1.6 < z ≤ 2.1 (Hercules-Corona Borealis Great Wall). From their Figure 3 of Horváth et al (2014) or Figure 4 of Horváth et al (2015) it is seen that the clustering happens at l ≈ 70…”

New results in applying the machine learning to GRB redshift estimation

“…Lately, with the help of multi-and uni-variate statistical analysis techniques an intermediate group was found [3,4,5,6,7,8,9,10,11,12,13]. Furthermore, recent publications have discovered large structures based on GRBs: the HerculesBorealis great wall at z ≈ 2 [14,15] and the Giant GRB ring at z ≈ 0.8 [16,17]. More GRBs with known redshift are necessary to understand the genesis of these structures.…”