[2604.17534] A Giant Ring on the sky

4σ$ ellipse features corresponding to the GR prediction and to the visually-identified GR. Additionally, the 2D Power Spectrum Analysis identified significant ($3.5 σ$) clustering on scales ~320Mpc. We also applied our statistical assessments to random data and to FLAMINGO-10K simulated data. The results demonstrate that, while superficially `significant' elliptical shells can be reproduced in random data with the optimum ellipse-matching method (many trials giving the `look-elsewhere' effect), with 2D PSA all of the random fields, and FLAMINGO-10K fields, were found to be entirely consistent with random."/>

4\sigma$ ellipse features corresponding to the GR prediction and to the visually-identified GR. Additionally, the 2D Power Spectrum Analysis identified significant ($3.5 \sigma$) clustering on scales ~320Mpc. We also applied our statistical assessments to random data and to FLAMINGO-10K simulated data. The results demonstrate that, while superficially `significant' elliptical shells can be reproduced in random data with the optimum ellipse-matching method (many trials giving the `look-elsewhere' effect), with 2D PSA all of the random fields, and FLAMINGO-10K fields, were found to be entirely consistent with random." />

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Astrophysics > Cosmology and Nongalactic Astrophysics

arXiv:2604.17534 (astro-ph)

[Submitted on 19 Apr 2026]

Title:A Giant Ring on the sky

Authors:Alexia M. Lopez, Roger G. Clowes<br>View a PDF of the paper titled A Giant Ring on the sky, by Alexia M. Lopez and 1 other authors

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Abstract:We present the discovery of `A Giant Ring on the Sky' (GR); a ring-like, ultra-large-scale structure at z~0.8, located in the same field that contains the previously-documented Giant Arc (GA) and Big Ring (BR). The GR was predicted from the presence of a Northern Arc (NA) filament (noted in previous work), which looked like it could, with more or enhanced data, connect with the GA to form a giant ring that encompasses the BR. There is now much evidence to support the reality of a GR. There appear to be two overlapping versions of the GR which differ by only the left-hand-side trajectory; this branching in the LHS of the GR was identified with the FilFinder algorithm and appears to correspond to both the GR prediction (the extended, elliptical, GR from the GA+NA ellipse), and the visually-identified ellipse (the visually-impressive, almost contiguous, roughly circular, GR which is enhanced by a tilted viewing angle). The branching in the GR seems to be hinting at multiple, overlapping ring features. The GR consists of a thin, filamentary northern region, a clustered, ambiguous southern region (including the members of the GA), and filamentary branching towards the LHS. Statistical assessment with elliptical shells, and optimum elliptical-shell-matching, identified two $> 4\sigma$ ellipse features corresponding to the GR prediction and to the visually-identified GR. Additionally, the 2D Power Spectrum Analysis identified significant ($3.5 \sigma$) clustering on scales ~320Mpc. We also applied our statistical assessments to random data and to FLAMINGO-10K simulated data. The results demonstrate that, while superficially `significant' elliptical shells can be reproduced in random data with the optimum ellipse-matching method (many trials giving the `look-elsewhere' effect), with 2D PSA all of the random fields, and FLAMINGO-10K fields, were found to be entirely consistent with random.

Subjects:

Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Cite as:<br>arXiv:2604.17534 [astro-ph.CO]

(or<br>arXiv:2604.17534v1 [astro-ph.CO] for this version)

https://doi.org/10.48550/arXiv.2604.17534

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arXiv-issued DOI via DataCite

Submission history<br>From: Alexia Lopez Dr [view email]<br>[v1]<br>Sun, 19 Apr 2026 16:50:56 UTC (10,349 KB)

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