Re-examining the evidence of the Hercules–Corona Borealis Great Wall

Abstract

In the lambda cold dark matter paradigm of cosmology, anisotropies larger than 260 Mpc should not exist. However, the existence of the Hercules–Corona Borealis Great Wall (HCB) is purported to challenge this principle by some with an estimated size exceeding 2000 Mpc. Recently, some have challenged the assertion of the existence of the HCB, attributing the anisotropy to sky exposure effects. It has never been explained why the original methods purporting the existence of the HCB produce anisotropies, even if sky-exposure effects are taken into account. In this paper, I apply the methods of the original papers purporting the existence of the HCB in various Monte Carlo simulations that assume isotropy to analyse the empirical meaning of the significance levels of the original tests used. I find that, although the statistical tests at first glance show significant anisotropies present in the suspect sample, Monte Carlo simulations can easily reproduce the sample in most cases, and if not, the differences can be accounted for by other statistical considerations. An updated sample raises the probability of drawing the observed clustering from an isotropic sample ten-fold in some cases. Thus the statistical tests used in prior studies overestimate the significance of the observed anisotropy, and an updated sample returns even less significant probabilities. Given the ability to reproduce the observed anisotropy in Monte Carlo simulations, the new, higher probabilities of being drawn from isotropy for an updated sample, and the work of previous papers attributing anisotropies to sky-selection effects, the existence of the HCB must be treated as doubtful at best.

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

“…There are claims of large structures in the Universe that appear challenging for the hypothesised transition to homogeneity, for example the Sloan Great Wall [702], the Huge Large Quasar Group [1309] or the Hercules-Corona Borealis Great Wall [1310]. These claims of violations of the cosmological principle have quickly been countered [1311][1312][1313][1314], usually on statistics alone. In short, despite a host of claims, there is little evidence to support any breakdown of the cosmological principle, at least with inhomogeneities.…”

Doubt on the statistical significance of the Giant GRB Ring

“…However, no independent examination on the statistical arguments of Balázs et al (2015Balázs et al ( , 2018 has taken place thus far. This situation is different from that of the Hercules-Corona Borealis Great Wall (Horváth et al 2014;Horváth et al 2015;Horváth et al 2020), another gigaparsec-scale association of GRBs at z ∼ 2, which has been studied critically by other authors (Christian 2020;Fujii 2022;Ukwatta & Wo źniak 2016). In this paper, we examine the original methodology of Balázs et al (2015) and revisit the statistical significance of the GGR.…”

A Giant Arc on the Sky

“…1 See also: Christian (2020) 2 See also: Nadathur (2013); Marinello et al (2016); Hutsemékers et al (2014) 3 See also : Marchã & Browne (2021) there is still uncertainty about the relative importance of morphology, luminosity, impact parameter, galaxy inclination etc., and combinations of these, that lead to the different classes (weak, strong) of absorbers. See for example: Lanzetta & Bowen (1990); Churchill et al (2000); Steidel et al (2002); Churchill et al (2005); Chen et al (2010); Bordoloi et al (2011).…”