JWST evidence for a sharp "Cosmic Daybreak" at z = 15
Abstract
Luminous young galaxies have been uncovered with relative ease by JWST, extending to z=14.5, so it is puzzling that deeper spectroscopy of fainter candidates now finds only interlopers. This redshift `ìmpasse" is underscored by the measured stellar ages of these high-z galaxies, which we show converge to zero by z=15, with a marked absence of earlier star-formation. Taken literally, such a late transition from the Dark Ages to luminous galaxies is unlike the gradual Cosmic Dawn of standard LCDM, but does confirm a key prediction of Wave Dark Matter, ψDM, as a Bose-Einstein condensate. The de Broglie wave pressure resists gravity until a substantial Jeans mass of 4× 109M⊙ is overcome at z=15, corresponding to a light boson mψ=2.2−0.3+0.4 × 10−22eV, and similar to independent estimates from lensing anomalies and dwarf galaxies. Furthermore, the substantial luminosities of the highest redshift galaxies appear to converge to the initial Jeans scale of ψDM, whereas LCDM predictions extend to lower luminosities and larger ages than observed. These contrasting predictions can be definitively tested as JWST observations accumulate, with diametric implications for Dark Matter as heavy particles beyond the Standard Model or ultra-light bosons motivated by the String Axiverse.
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BibTeX
@misc{zhang2026jwst,
title = {{JWST evidence for a sharp "Cosmic Daybreak" at z = 15}},
author = {Jiashuo Zhang and Tom Broadhurst and Tzihong Chiueh and Hsi-Yu Schive and Keiichi Umetsu and Jose M. Diego and Paloma Morilla and Alvaro Pozo and Chian-Chou Chen and Jeremy Lim and Pablo G. Perez-Gonzalez and Rogier Windhorst},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28257},
eprint = {2609.28257},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28257},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - JWST evidence for a sharp "Cosmic Daybreak" at z = 15
AU - Jiashuo Zhang
AU - Tom Broadhurst
AU - Tzihong Chiueh
AU - Hsi-Yu Schive
AU - Keiichi Umetsu
AU - Jose M. Diego
AU - Paloma Morilla
AU - Alvaro Pozo
AU - Chian-Chou Chen
AU - Jeremy Lim
AU - Pablo G. Perez-Gonzalez
AU - Rogier Windhorst
PY - 2026
DA - 2026/09/27
PB - arXiv
DO - 10.48550/arxiv.2609.28257
UR - https://arxiv.org/abs/2609.28257
AB - Luminous young galaxies have been uncovered with relative ease by JWST, extending to z=14.5, so it is puzzling that deeper spectroscopy of fainter candidates now finds only interlopers. This redshift `ìmpasse" is underscored by the measured stellar ages of these high-z galaxies, which we show converge to zero by z=15, with a marked absence of earlier star-formation. Taken literally, such a late transition from the Dark Ages to luminous galaxies is unlike the gradual Cosmic Dawn of standard LCDM, but does confirm a key prediction of Wave Dark Matter, ψDM, as a Bose-Einstein condensate. The de Broglie wave pressure resists gravity until a substantial Jeans mass of 4× 10^9M_⊙ is overcome at z=15, corresponding to a light boson m_ψ=2.2_−0.3^+0.4 × 10^−22eV, and similar to independent estimates from lensing anomalies and dwarf galaxies. Furthermore, the substantial luminosities of the highest redshift galaxies appear to converge to the initial Jeans scale of ψDM, whereas LCDM predictions extend to lower luminosities and larger ages than observed. These contrasting predictions can be definitively tested as JWST observations accumulate, with diametric implications for Dark Matter as heavy particles beyond the Standard Model or ultra-light bosons motivated by the String Axiverse.
ER -