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arxiv: 2607.01172 · v1 · pith:UQ3E6RTUnew · submitted 2026-07-01 · 🌌 astro-ph.CO

The local galaxy distribution does not violate the cosmological principle

Till Sawala (1) ((1) University of Helsinki) This is my paper

Pith reviewed 2026-07-02 06:20 UTC · model grok-4.3

classification 🌌 astro-ph.CO
keywords cosmological principleDESI DR1galaxy distributioncomoving distancelarge-scale structureΛCDManisotropy
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The pith

The reported gigaparsec anisotropy in DESI galaxy data vanishes once the correct comoving distance scale is applied.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

A recent claim based on DESI DR1 data identified large-scale coherent anisotropic features that appeared to violate the cosmological principle of statistical homogeneity and isotropy. Re-analysis of the same galaxy samples shows these features arise solely from an incorrect choice of distance scale. When the proper comoving distances are used, the apparent anomaly disappears and the observed structures match the distributions produced by the FLAMINGO hydrodynamic simulation run in the standard ΛCDM cosmology. The result indicates that the local galaxy distribution remains consistent with the foundational assumptions of the standard cosmological model.

Core claim

The apparent anomaly in the DESI DR1 galaxy distribution disappears when the correct comoving distance scale is used; rather than violating the cosmological principle, the observed structures are consistent with those expected in a ΛCDM Universe as reproduced by the FLAMINGO simulation.

What carries the argument

Re-calculation of the DESI DR1 galaxy positions using the correct comoving distance scale, followed by direct comparison to the galaxy distribution in the FLAMINGO ΛCDM simulation.

Load-bearing premise

The FLAMINGO simulation run in the standard ΛCDM paradigm accurately reproduces the expected galaxy distribution in the real universe at the relevant scales.

What would settle it

A statistically significant mismatch between the corrected DESI DR1 galaxy distribution and the corresponding output from the FLAMINGO simulation at gigaparsec scales would falsify the central claim.

read the original abstract

The cosmological principle, which states that the Universe is statistically homogeneous and isotropic on sufficiently large scales, is a foundational assumption of the standard cosmological model. A recent analysis of DESI DR1 galaxy samples reported coherent anisotropic features in the local galaxy distribution extending to gigaparsec scales. If correct, this result would directly contradict the cosmological principle and motivate inhomogeneous cosmologies. Here I analyse the same data and compare them with galaxy distributions predicted by the FLAMINGO cosmological hydrodynamic simulation, performed in the standard $\Lambda$CDM paradigm. I show that the apparent anomaly disappears when the correct comoving distance scale is used. I also show that, rather than violating the cosmological principle, the observed structures are consistent with those expected in a $\Lambda$CDM Universe.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The paper reanalyzes DESI DR1 galaxy samples previously reported to show coherent anisotropic features on Gpc scales that would violate the cosmological principle. It claims these features disappear upon applying the correct comoving distance scale and demonstrates that the observed structures match those in the FLAMINGO hydrodynamic simulation run in the standard ΛCDM paradigm.

Significance. If the central claim holds, the work would remove a reported challenge to the cosmological principle, showing that local galaxy structures are consistent with ΛCDM expectations rather than requiring inhomogeneous models. The use of public data reprocessing and direct simulation comparison provides a concrete test of the anomaly.

major comments (2)
  1. [Abstract and §3] Abstract and §3 (distance scaling analysis): the claim that the anomaly vanishes with the 'correct comoving distance scale' is not accompanied by an explicit description of the correction formula, the original vs. revised distance computation, or quantitative metrics (e.g., the value of the anisotropic statistic before and after correction with uncertainties).
  2. [§4] §4 (simulation comparison): the consistency conclusion with FLAMINGO rests on matching observed structures to the simulation output, but no values are reported for the specific anisotropic statistic used in the original DESI analysis, no error bars from multiple independent realizations are shown, and the simulation volume and DESI-like selection function matching are not quantified to address cosmic variance on Gpc scales.
minor comments (1)
  1. Figure captions should explicitly state the number of simulation realizations averaged and the precise selection cuts applied to match DESI DR1.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their thorough and constructive review. We address each major comment below and will revise the manuscript to incorporate the requested clarifications and quantitative details.

read point-by-point responses

  1. Referee: [Abstract and §3] Abstract and §3 (distance scaling analysis): the claim that the anomaly vanishes with the 'correct comoving distance scale' is not accompanied by an explicit description of the correction formula, the original vs. revised distance computation, or quantitative metrics (e.g., the value of the anisotropic statistic before and after correction with uncertainties).

    Authors: We agree that an explicit description of the distance correction is required for clarity and reproducibility. In the revised manuscript we will provide the precise correction formula, contrast the original and revised comoving distance computations, and report the numerical values of the anisotropic statistic before and after correction together with their uncertainties. revision: yes

  2. Referee: [§4] §4 (simulation comparison): the consistency conclusion with FLAMINGO rests on matching observed structures to the simulation output, but no values are reported for the specific anisotropic statistic used in the original DESI analysis, no error bars from multiple independent realizations are shown, and the simulation volume and DESI-like selection function matching are not quantified to address cosmic variance on Gpc scales.

    Authors: We acknowledge that additional quantitative information would strengthen the comparison. In the revision we will report the values of the anisotropic statistic for both the DESI data and the FLAMINGO output, include error bars from the available realizations, and quantify the simulation volume together with the application of the DESI-like selection function to address cosmic variance on Gpc scales. revision: yes

Circularity Check

0 steps flagged

No circularity; external simulation benchmark is independent

full rationale

The paper reprocesses public DESI DR1 data and compares observed structures to galaxy catalogs from the independent FLAMINGO hydrodynamic simulation run in standard ΛCDM. No parameters are fitted to the target data, no self-citations support the central consistency claim, and the distance-scale correction is presented as a direct reanalysis rather than a derived quantity. The result is therefore self-contained against an external benchmark and does not reduce to any of the enumerated circular patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the domain assumption that the FLAMINGO ΛCDM simulation provides a faithful benchmark for real galaxy distributions and that the original analysis used an incorrect comoving distance scale; no free parameters or invented entities are introduced in the abstract.

axioms (1)
  • domain assumption The FLAMINGO simulation accurately represents the galaxy distribution expected in a ΛCDM universe at gigaparsec scales.
    Invoked when stating that observed structures are consistent with simulation output.

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discussion (0)

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Reference graph

Works this paper leans on

40 extracted references · 40 canonical work pages · 2 internal anchors

  1. [1]

    Data Release 1 of the Dark Energy Spectroscopic Instrument

    “Data Release 1 of the Dark Energy Spectroscopic Instrument. ” Astronomical Journal171 (5): 285.10.3847/1538-3881/ae4c43. Astropy Collaboration, Adrian M. Price-Whelan, Pey Lian Lim, Nicholas Earl, Nathaniel Starkman, Larry Bradley, David L. Shupe, Aarya A. Patil, Lia Corrales, C. E. Brasseur, et al

    work page doi:10.3847/1538-3881/ae4c43

  2. [2]

    The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package

    “The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package. ”The Astrophysical Journal935 (2): 167 . 10.3847/1538-4357/ac7c74. Astropy Collaboration, Thomas P . Robitaille, Erik J. Tollerud, Perry Greenfield, Michael Droett- boom, Erik Bray, Tom Aldcroft, Matt Davis, Adam G...

    work page internal anchor Pith review doi:10.3847/1538-4357/ac7c74

  3. [3]

    , archivePrefix = "arXiv", eprint =

    “ Astropy: A community Python package for astronomy. ”Astronomy and Astrophysics558: A33.10.1051/0004-6361/201322068. Balázs, Lajos G., Lídia Rejtő, and Gábor Tusnády

    work page doi:10.1051/0004-6361/201322068

  4. [4]

    Some statistical remarks on the giant GRB ring

    “Some statistical remarks on the giant GRB ring. ”MNRAS473 (3): 3169–3179 .10.1093/mnras/stx2550. Buchert, T. and S. Räsänen

    work page doi:10.1093/mnras/stx2550

  5. [5]

    Spatially homogeneous universes with late-time anisotropy

    “Spatially homogeneous universes with late-time anisotropy. ”Classical and Quantum Gravity40 (24): 245015.10.1088/1361-6382/ad0b36. Courtois, H. M., J. Mould, A. M. Hollinger, A. Dupuy, and C. P . Zhang

    work page doi:10.1088/1361-6382/ad0b36

  6. [6]

    , keywords =

    “The evolution of large-scale structure in a universe dominated by cold dark matter. ”ApJ292: 371–394. 10.1086/163168. de Lapparent, V ., M. J. Geller, and J. P . Huchra

    work page doi:10.1086/163168

  7. [7]

    A slice of the Universe

    “A slice of the Universe. ”ApJ302: L1–L5. DESI Collaboration, M. Abdul Karim, J. Aguilar, S. Ahlen, S. Alam, L. Allen, et al. 2025a. “DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints. ” Physical Review D112: 083515.10.1103/tr6y-kpc6. DESI Collaboration, A. G. Adame, J. Aguilar, S. Ahlen, S. Alam, D. M. Alexand...

    work page doi:10.1103/tr6y-kpc6 2024

  8. [8]

    Einasto, M., L

    10.1088/1475-7516/2025/02/021. Einasto, M., L. J. Liivamägi, E. Tempel, E. Saar, E. Tago, P . Einasto, I. Enkvist, J. Einasto, V . J. Martínez, P . Heinämäki, et al

    work page doi:10.1088/1475-7516/2025/02/021 2025

  9. [9]

    The Sloan Great Wall. Morphology and galaxy content

    “The Sloan Great Wall. Morphology and galaxy content. ” The Astrophysical Journal736 (1): 51.10.1088/0004-637X/736/1/51. Forouhar Moreno, Victor J., John Helly, Robert McGibbon, Joop Schaye, Matthieu Schaller, Jiaxin Han, Roi Kugel, and Yannick M. Bahé

    work page doi:10.1088/0004-637x/736/1/51

  10. [10]

    Assessing subhalo finders in cosmological hydrodynamical simulations

    “Assessing subhalo finders in cosmological hydrodynamical simulations. ”Monthly Notices of the Royal Astronomical Society543 (2): 1339– 1372.10.1093/mnras/staf1478. Fujii, Hirokazu

    work page doi:10.1093/mnras/staf1478

  11. [11]

    Critical assessment of the recent report on the gigaparsec-scale correlation of the orientations of large quasar groups

    “Critical assessment of the recent report on the gigaparsec-scale correlation of the orientations of large quasar groups. ”MNRAS527 (2): 1982–1992. 10.1093/mnras/ stad3356. Geller, M. J. and J. P . Huchra. 1989 . “Mapping the Universe. ”Science246: 897–903. Gott, III, J. Richard et al

    work page doi:10.1093/mnras/ 1982

  12. [12]

    The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

    “The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation. ” Astronomical Journal165 (6): 253.10.3847/1538-3881/accff8. Han, Jiaxin, Shaun Cole, Carlos S. Frenk, Alejandro Benitez-Llambay, and John Helly

    work page doi:10.3847/1538-3881/accff8

  13. [13]

    HBT+: an improved code for finding subhaloes and building merger trees in cosmological simulations

    “HBT+: an improved code for finding subhaloes and building merger trees in cosmological simulations. ” MNRAS474 (1): 604–617 .10.1093/mnras/stx2792. Harris, Charles R., K. Jarrod Millman, St’efan J. van der Walt, Ralf Gommers, Pauli Virtanen, David Cournapeau, Eric Wieser, Julian Taylor, Sebastian Berg, Nathaniel J. Smith, et al

    work page doi:10.1093/mnras/stx2792

  14. [14]

    Harris and K

    “ Array programming with NumPy. ”Nature585 (7825): 357–362.10.1038/s41586-020-2649-2. Helly, John C., Robert J. McGibbon, Joop Schaye, Matthieu Schaller, William McDonald, Joey Braspenning, Jeger C. Broxterman, Emily E. Costello, Willem Elbers, Victor J. Forouhar Moreno, et al

    work page doi:10.1038/s41586-020-2649-2

  15. [16]

    The FLAMINGO simulations data release

    48550/arXiv.2604.24324. Huchra, J. P . and M. J. Geller

    work page internal anchor Pith review Pith/arXiv arXiv

  16. [17]

    Groups of Galaxies. I. Nearby groups

    “Groups of Galaxies. I. Nearby groups. ”ApJ257: 423–437 . 10.1086/160000. Hunter, J. D. 2007 . “Matplotlib: A 2D graphics environment. ”Computing in Science & Engineering 9 (3): 90–95.10.1109/MCSE.2007.55. Keenan, R. C., A. J. Barger, and L. L. Cowie

    work page doi:10.1086/160000 2007

  17. [18]

    Evidence for a ∼300 Megaparsec Scale Under- density in the Local Galaxy Distribution

    “Evidence for a ∼300 Megaparsec Scale Under- density in the Local Galaxy Distribution. ”ApJ775: 62.10.1088/0004-637X/775/1/62. Kugel, Roi, Joop Schaye, Matthieu Schaller, John C. Helly, Joey Braspenning, Willem Elbers, Carlos S. Frenk, Ian G. McCarthy, Juliana Kwan, Jaime Salcido, et al

    work page doi:10.1088/0004-637x/775/1/62

  18. [19]

    , keywords =

    “FLAMINGO: Calibrating large cosmological hydrodynamical simulations with machine learning. ”Monthly Notices of the Royal Astronomical Society526 (4): 6103–6127 .10.1093/mnras/stad2540. 18 Kumar Aluri, Pavan, Paolo Cea, Pravabati Chingangbam, Ming-Chung Chu, Roger G. Clowes, Damien Hutsemékers, Joby P . Kochappan, Alexia M. Lopez, Lang Liu, Niels C. M. Ma...

    work page doi:10.1093/mnras/stad2540

  19. [20]

    Is the observable Universe consistent with the cosmological principle?

    “Is the observable Universe consistent with the cosmological principle?”Classical and Quantum Gravity40 (9): 094001.10.1088/1361-6382/acbefc. Lan, Ting-Wen et al

    work page doi:10.1088/1361-6382/acbefc

  20. [21]

    The DESI Survey Validation: Results from Visual Inspection of Bright Galaxies, Luminous Red Galaxies, and Emission Line Galaxies

    “The DESI Survey Validation: Results from Visual Inspection of Bright Galaxies, Luminous Red Galaxies, and Emission Line Galaxies. ”Astrophysical Journal943 (1): 68.10.3847/1538-4357/aca5fa. Land-Strykowski, M., G. F. Lewis, and T. Murphy

    work page doi:10.3847/1538-4357/aca5fa

  21. [22]

    Lopez, Alexia M., Roger G

    10.3847/1538- 4357/ad01bb. Lopez, Alexia M., Roger G. Clowes, and Gerard M. Williger

    work page doi:10.3847/1538-

  22. [23]

    A Giant Arc on the Sky

    “A Giant Arc on the Sky. ”MNRAS 516 (2): 1557–1572.10.1093/mnras/stac2204. Lopez, Alexia M., Roger G. Clowes, and Gerard M. Williger

    work page doi:10.1093/mnras/stac2204

  23. [24]

    Investigating Ultra-Large Large-Scale Structures: Potential Implications for Cosmology

    “Investigating Ultra-Large Large-Scale Structures: Potential Implications for Cosmology. ”arXiv e-printsarXiv:2409 .14894. 10.48550/arXiv.2409.14894. Marinello, Gabriel E., Roger G. Clowes, Luis E. Campusano, Gerard M. Williger, Ilona K. Söchting, and Matthew J. Graham

    work page doi:10.48550/arxiv.2409.14894

  24. [25]

    Compatibility of the large quasar groups with the concordance cosmological model

    “Compatibility of the large quasar groups with the concordance cosmological model. ”MNRAS461 (3): 2267–2281.10.1093/mnras/stw1513. Mazurenko, Sergij, Indranil Banik, and Pavel Kroupa

    work page doi:10.1093/mnras/stw1513

  25. [26]

    10.21105/joss. 08252. Meissner, Krzysztof A. and Roger Penrose

    work page doi:10.21105/joss

  26. [27]

    The Physics of Conformal Cyclic Cosmology

    “The Physics of Conformal Cyclic Cosmology. ” arXiv e-printsarXiv:2503.24263.10.48550/arXiv.2503.24263. Migkas, K. et al

    work page doi:10.48550/arxiv.2503.24263

  27. [28]

    Probing cosmic isotropy with a new X-ray galaxy cluster sample through the LX-T scaling relation

    “Probing cosmic isotropy with a new X-ray galaxy cluster sample through the LX-T scaling relation. ”A&A636: A15.10.1051/0004-6361/201936602. Nadathur, Seshadri

    work page doi:10.1051/0004-6361/201936602

  28. [29]

    Seeing patterns in noise: gigaparsec-scale ‘structures’ that do not violate homogeneity

    “Seeing patterns in noise: gigaparsec-scale ‘structures’ that do not violate homogeneity. ”MNRAS434 (1): 398–406.10.1093/mnras/stt1028. Park, Changbom, Yun-Young Choi, Juhan Kim, III Gott, J. Richard, Sungsoo S. Kim, and Kap-Sung Kim

    work page doi:10.1093/mnras/stt1028

  29. [30]

    The Challenge of the Largest Structures in the Universe to Cosmology

    “The Challenge of the Largest Structures in the Universe to Cosmology. ”ApJ759 (1): L7 .10.1088/2041-8205/759/1/L7. Park, Changbom, Hyunmi Song, Maret Einasto, Heidi Lietzen, and Pekka Heinamaki

    work page doi:10.1088/2041-8205/759/1/l7 2041

  30. [31]

    Large SDSS Quasar Groups and Their Statistical Significance

    “Large SDSS Quasar Groups and Their Statistical Significance. ”Journal of Korean Astronomical Society 48 (1): 75–82.10.5303/JKAS.2015.48.1.75. Peebles, P . J. E. 1980.The large-scale structure of the universe. Princeton University Press. Sawala, Till, Carlos Frenk, Jens Jasche, Peter H. Johansson, and Guilhem Lavaux

    work page doi:10.5303/jkas.2015.48.1.75 2015

  31. [32]

    Distinct 19 distributions of elliptical and disk galaxies across the Local Supercluster as aΛCDM prediction

    “Distinct 19 distributions of elliptical and disk galaxies across the Local Supercluster as aΛCDM prediction. ” Nature Astronomy8: 247–255.10.1038/s41550-023-02130-6. Sawala, Till, Meri Teeriaho, Carlos S. Frenk, John Helly, Adrian Jenkins, Gabor Racz, Matthieu Schaller, and Joop Schaye

    work page doi:10.1038/s41550-023-02130-6

  32. [33]

    The Emperor’s New Arc: gigaparsec patterns abound in a ΛCDM universe

    “The Emperor’s New Arc: gigaparsec patterns abound in a ΛCDM universe. ”MNRAS.10.1093/mnrasl/slaf021. Schaller, Matthieu

    work page doi:10.1093/mnrasl/slaf021

  33. [34]

    On the anisotropic distribution of clusters in the local Universe

    “On the anisotropic distribution of clusters in the local Universe. ”MNRAS 529 (1): L23–L27 .10.1093/mnrasl/slad199. Schaye, Joop, Roi Kugel, Matthieu Schaller, John C. Helly, Joey Braspenning, Willem Elbers, Ian G. McCarthy, Marcel P . van Daalen, Bert Vandenbroucke, Carlos S. Frenk, et al

    work page doi:10.1093/mnrasl/slad199

  34. [35]

    , keywords =

    “The FLAMINGO project: cosmological hydrodynamical simulations for large-scale structure and galaxy cluster surveys. ”MNRAS526 (4): 4978–5020.10.1093/mnras/stad2419. Secrest, N. J. et al

    work page doi:10.1093/mnras/stad2419

  35. [36]

    The dipole of the Pantheon+SH0ES data

    “The dipole of the Pantheon+SH0ES data. ”JCAP 2023 (11): 054.10.1088/1475-7516/2023/11/054. Springel, V ., S. D. M. White, A. Jenkins, C. S. Frenk, N. Yoshida, L. Gao, J. Navarro, R. Thacker, D. Croton, J. Helly, et al

    work page doi:10.1088/1475-7516/2023/11/054 2023

  36. [37]

    Nature , archivePrefix = "arXiv", eprint =

    “Simulations of the formation, evolution and clustering of galaxies and quasars. ”Nature435: 629–636.10.1038/nature03597. Sylos Labini, F. and T. Antal

    work page doi:10.1038/nature03597

  37. [38]

    Large-scale galaxy correlations from the DESI first data release

    “Large-scale galaxy correlations from the DESI first data release. ” A&A707: A254.10.1051/0004-6361/202558271. Sylos Labini, Francesco and Marco Galoppo

    work page doi:10.1051/0004-6361/202558271

  38. [39]

    Detection of anisotropic cosmic structures on a gigaparsec scale

    “Detection of anisotropic cosmic structures on a gigaparsec scale. ”Nature. 10.1038/s41586-026-10702-5 . Published online 24 June

    work page doi:10.1038/s41586-026-10702-5

  39. [40]

    The Laniakea supercluster of galaxies

    “The Laniakea supercluster of galaxies. ”Nature513: 71–73.10.1038/nature13674. Valade, A. et al

    work page doi:10.1038/nature13674

  40. [41]

    Analysing the large-scale bulk flow using cosmicflows4: increasing tension with the standard cosmological model

    “Analysing the large-scale bulk flow using cosmicflows4: increasing tension with the standard cosmological model. ”MNRAS524: 1885–1892. White, Simon D. M., Carlos S. Frenk, Marc Davis, and George Efstathiou. 1987 . “Clusters, Filaments, and Voids in a Universe Dominated by Cold Dark Matter. ”ApJ313: 505.10.1086/164990. 20

    work page doi:10.1086/164990 1987