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arXiv · 2609.36656

An Ionized Superstructure at Cosmic Dawn Revealed by a Foundation Model for Astrophysical Research

Minghao Yue·Yongda Zhu·Jiani Ding·Xiaohui Fan·Yufeng Luo
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Abstract

The spatial structure of cosmic reionization remains poorly constrained. Using a foundation model trained for James Webb Space Telescope datasets, we identify a luminous galaxy at redshift $z=7.567$ showing strong Ly$α$ transmission at $z=6.80\pm0.07$. The transmission extends over $210.5^{+55.7}_{-53.5}$ comoving megaparsecs, indicating an ionized superstructure with hydrogen neutral fraction $x_{\rm HI}=(2.07^{+0.29}_{-0.30})\times10^{-6}$, in an epoch when the cosmic mean neutral fraction is $\sim0.4$. Cosmological simulations suggest a probability of $\approx10^{-5}$ for a random sightline to reproduce the signal. We find no significant galaxy overdensity associated with the transmission region, in tension with canonical inside-out reionization models. These observations severely challenge existing reionization models in the standard $Λ$CDM Universe, and provide the first example of deep learning discovering a previously unknown astrophysical phenomenon.

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Minghao Yue, Yongda Zhu, Jiani Ding, Xiaohui Fan, Yufeng Luo. 2026-09-29. An Ionized Superstructure at Cosmic Dawn Revealed by a Foundation Model for Astrophysical Research. https://arxiv.org/abs/2609.36656

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