English

Do high redshift QSOs and GRBs corroborate JWST?

Cosmology and Nongalactic Astrophysics 2025-06-02 v3 General Relativity and Quantum Cosmology High Energy Physics - Phenomenology

Abstract

The James Webb Space Telescope (JWST) is reporting massive high redshift galaxies that appear challenging from the Λ\LambdaCDM perspective. Interpreted as a cosmological problem, this necessitates the Planck collaboration underestimating either matter density Ωm\Omega_m or physical matter density Ωmh2\Omega_m h^2 at higher redshifts. Through standard frequentist profile likelihoods, we identify corroborating quasar (QSO) and gamma-ray burst (GRB) data sets where Ωm\Omega_m increases with effective redshift zeffz_{\textrm{eff}} and remains anomalously large at higher redshifts. We relax the traditional priors by allowing for Ωm>1\Omega_m > 1, consistent with negative dark energy density, to locate profile likelihood peaks where possible. While the variation of Ωm\Omega_m with zeffz_{\textrm{eff}} is at odds with the Λ\LambdaCDM model, demarcating frequentist confidence intervals through differences in χ2\chi^2 in profile likelihoods, the prevailing technique in the literature, points to 3.9σ3.9 \sigma and 7.9σ7.9 \sigma tensions between GRBs and QSOs, respectively, and Planck-Λ\LambdaCDM. We explain the approximations inherent in the existing profile likelihood literature, and highlight fresh methodology that generalises the prescription. We show that alternative methods, including Bayesian approaches, lead to similar tensions. Finally, in the large sample limit, we show that Feldman-Cousins prescription for frequentist confidence intervals in the presence of a boundary (prior) leads to confidence intervals that are bounded above by Wilks' theorem.

Keywords

Cite

@article{arxiv.2405.19953,
  title  = {Do high redshift QSOs and GRBs corroborate JWST?},
  author = {Eoin Ó Colgáin and M. M. Sheikh-Jabbari and Lu Yin},
  journal= {arXiv preprint arXiv:2405.19953},
  year   = {2025}
}

Comments

v2 comments on frequentist confidence intervals added; v3 to appear in Physics of the Dark Universe

R2 v1 2026-06-28T16:47:01.894Z