The scale of homogeneity in DESI Data Release 1
Abstract
We present measurements of the scale of cosmic homogeneity using the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI), the largest publicly available spectroscopic extragalactic survey to date. Using a counts-in-spheres estimator applied to nearly 5 million galaxies and quasars across six independent redshift bins spanning 0.1 < z < 2.1, we measure the correlation dimension D2(r) and define the homogeneity scale RH as the point at which the galaxy distribution reaches within 1\% of the homogeneous asymptotic value. We find that all tracers clearly transition to homogeneity, with the galaxy homogeneity scale ranging from 93.8+0.9−0.7 to 142.6+1.4−1.4 h−1Mpc depending on the tracer redshift, galaxy bias, and modelling used to extract the scale. Using a cosmology-dependent model, we reconstruct the underlying matter homogeneity scale, finding it decreases monotonically with redshift in excellent agreement with ΛCDM predictions. We identify a systematic offset of up to ∼ 10% between measurements in the North and South Galactic Caps, largely due to fiber assignment effects reproduced in our simulations. Accounting for this, and with a complementary demonstration using toy models that our methodology correctly identifies inhomogeneous universes in all but rather finely-tuned observer configurations, this hence provides strong evidence in favour of the cosmological principle across our full redshift range. Our matter homogeneity scale measurements are consistent with, and substantially more precise than, previous constraints from WiggleZ and SDSS, demonstrating the power of DESI data for precision tests of the cosmological principle.
Related
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- Confirming HSC strong lens candidates with DESI Spectroscopy. II. Analysis of 80 galaxy-scale systems with lens redshifts above 0.8
BibTeX
@misc{howlett2026scale,
title = {{The scale of homogeneity in DESI Data Release 1}},
author = {Cullan Howlett and L. Giani and Elizabeth G. O'Brien and A. Whitford and Tamara M. Davis and J. Aguilar and S. Ahlen and U. Andrade and E. Armengaud and S. BenZvi and F. Beutler and D. Bianchi and D. Brooks and R. Canning and A. Carnero Rosell and F. J. Castander and E. Chaussidon and T. Claybaugh and A. Cuceu and A. de la Macorra and Arjun Dey and Biprateep Dey and P. Doel and D. Forero-Sánchez and J. E. Forero-Romero and E. Gaztañaga and Satya Gontcho A Gontcho and G. Gutierrez and C. Hahn and K. Honscheid and D. Huterer and M. Ishak and S. Juneau and T. Karim and D. Kirkby and A. Kremin and O. Lahav and A. Lambert and C. Lamman and M. Landriau and L. Le Guillou and M. Manera and A. Meisner and R. Miquel and J. Moustakas and S. Nadathur and J. A. Newman and H. E. Noriega and E. Paillas and N. Palanque-Delabrouille and W. J. Percival and C. Poppett and F. Prada and I. Pérez-Ràfols and C. Ravoux and G. Rossi and R. Ruggeri and L. Samushia and E. Sanchez and C. Saulder},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38083},
eprint = {2610.38083},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38083},
}
RIS
TY - UNPB
TI - The scale of homogeneity in DESI Data Release 1
AU - Cullan Howlett
AU - L. Giani
AU - Elizabeth G. O'Brien
AU - A. Whitford
AU - Tamara M. Davis
AU - J. Aguilar
AU - S. Ahlen
AU - U. Andrade
AU - E. Armengaud
AU - S. BenZvi
AU - F. Beutler
AU - D. Bianchi
AU - D. Brooks
AU - R. Canning
AU - A. Carnero Rosell
AU - F. J. Castander
AU - E. Chaussidon
AU - T. Claybaugh
AU - A. Cuceu
AU - A. de la Macorra
AU - Arjun Dey
AU - Biprateep Dey
AU - P. Doel
AU - D. Forero-Sánchez
AU - J. E. Forero-Romero
AU - E. Gaztañaga
AU - Satya Gontcho A Gontcho
AU - G. Gutierrez
AU - C. Hahn
AU - K. Honscheid
AU - D. Huterer
AU - M. Ishak
AU - S. Juneau
AU - T. Karim
AU - D. Kirkby
AU - A. Kremin
AU - O. Lahav
AU - A. Lambert
AU - C. Lamman
AU - M. Landriau
AU - L. Le Guillou
AU - M. Manera
AU - A. Meisner
AU - R. Miquel
AU - J. Moustakas
AU - S. Nadathur
AU - J. A. Newman
AU - H. E. Noriega
AU - E. Paillas
AU - N. Palanque-Delabrouille
AU - W. J. Percival
AU - C. Poppett
AU - F. Prada
AU - I. Pérez-Ràfols
AU - C. Ravoux
AU - G. Rossi
AU - R. Ruggeri
AU - L. Samushia
AU - E. Sanchez
AU - C. Saulder
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.38083
UR - https://arxiv.org/abs/2610.38083
AB - We present measurements of the scale of cosmic homogeneity using the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI), the largest publicly available spectroscopic extragalactic survey to date. Using a counts-in-spheres estimator applied to nearly 5 million galaxies and quasars across six independent redshift bins spanning 0.1 < z < 2.1, we measure the correlation dimension D_2(r) and define the homogeneity scale R_H as the point at which the galaxy distribution reaches within 1\% of the homogeneous asymptotic value. We find that all tracers clearly transition to homogeneity, with the galaxy homogeneity scale ranging from 93.8^+0.9_−0.7 to 142.6^+1.4_−1.4 h^−1Mpc depending on the tracer redshift, galaxy bias, and modelling used to extract the scale. Using a cosmology-dependent model, we reconstruct the underlying matter homogeneity scale, finding it decreases monotonically with redshift in excellent agreement with ΛCDM predictions. We identify a systematic offset of up to ∼ 10% between measurements in the North and South Galactic Caps, largely due to fiber assignment effects reproduced in our simulations. Accounting for this, and with a complementary demonstration using toy models that our methodology correctly identifies inhomogeneous universes in all but rather finely-tuned observer configurations, this hence provides strong evidence in favour of the cosmological principle across our full redshift range. Our matter homogeneity scale measurements are consistent with, and substantially more precise than, previous constraints from WiggleZ and SDSS, demonstrating the power of DESI data for precision tests of the cosmological principle.
ER -