PreprintarXiv licencearXiv
Blue-tilted spectral running and the JWST early galaxy tension
Abstract
Recently, the James Webb Space Telescope (JWST) collaboration has found the unexpectedly large abundance of massive galaxies with stellar masses of ∼ 1010 M⊙ at high redshifts z ≃ 6.5 − 9 compared with the prediction of the standard ΛCDM model. As a possible solution to the tension, we consider a blue-tilted spectrum of density perturbations with a positive running. We find that, for αs ≃ 0.02 and βs ≃ 0.02, a joint analysis with CMB observations shows that the tension can be resolved at the 1σ confidence level. Such a blue-tilted spectrum is also plausible from the perspective for formations of primordial black holes on much smaller scales in the early Universe.
Related
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BibTeX
@misc{kobayashi2026bluetilted,
title = {{Blue-tilted spectral running and the JWST early galaxy tension}},
author = {Mikage U. Kobayashi and Gen Chiaki and Kazutaka Kimura and Kazuyuki Akitsu and Kazunori Kohri and Tomo Takahashi and Kazuyuki Omukai},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.22161},
eprint = {2605.22161},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.22161},
}
RIS
TY - UNPB
TI - Blue-tilted spectral running and the JWST early galaxy tension
AU - Mikage U. Kobayashi
AU - Gen Chiaki
AU - Kazutaka Kimura
AU - Kazuyuki Akitsu
AU - Kazunori Kohri
AU - Tomo Takahashi
AU - Kazuyuki Omukai
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2605.22161
UR - https://arxiv.org/abs/2605.22161
AB - Recently, the James Webb Space Telescope (JWST) collaboration has found the unexpectedly large abundance of massive galaxies with stellar masses of ∼ 10^10 M_⊙ at high redshifts z ≃ 6.5 − 9 compared with the prediction of the standard ΛCDM model. As a possible solution to the tension, we consider a blue-tilted spectrum of density perturbations with a positive running. We find that, for α_s ≃ 0.02 and β_s ≃ 0.02, a joint analysis with CMB observations shows that the tension can be resolved at the 1σ confidence level. Such a blue-tilted spectrum is also plausible from the perspective for formations of primordial black holes on much smaller scales in the early Universe.
ER -