2023-09-11 ミシガン大学
◆この成果は、宇宙の構造成長に関する新たな洞察を提供し、宇宙論における「S8の矛盾」と呼ばれる課題への取り組みを促しています。研究者たちは、暗黒エネルギーや暗黒物質、一般相対性理論の拡張など、この効果の原因を理解しようとしています。
＜関連情報＞
- https://news.umich.edu/the-universe-caught-suppressing-cosmic-structure-growth/
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.111001
コンコーダンス宇宙モデルにおける構造成長の抑制の証拠 Evidence for Suppression of Structure Growth in the Concordance Cosmological Model
Nhat-Minh Nguyen, Dragan Huterer, and Yuewei Wen
Physical Review Letters Published 11 September 2023
DOI:https://doi.org/10.1103/PhysRevLett.131.111001
ABSTRACT
We present evidence for a suppressed growth rate of large-scale structure during the dark-energy-dominated era. Modeling the growth rate of perturbations with the “growth index” γ, we find that current cosmological data strongly prefer a higher growth index than the value γ=0.55 predicted by general relativity in a flat Lambda cold dark matter cosmology. Both the cosmic microwave background data from Planck and the large-scale structure data from weak lensing, galaxy clustering, and cosmic velocities separately favor growth suppression. When combined, they yield γ=0.633+0.025−0.024, excluding γ=0.55 at a statistical significance of 3.7σ. The combination of fσ8 and Planck measurements prefers an even higher growth index of γ=0.639+0.024−0.025, corresponding to a 4.2σ tension with the concordance model. In Planck data, the suppressed growth rate offsets the preference for nonzero curvature and fits the data equally well as the latter model. A higher γ leads to a higher matter fluctuation amplitude S8 inferred from galaxy clustering and weak lensing measurements, and a lower S8 from Planck data, effectively resolving the S8 tension.
