Model-independent measurement of the matter-radiation equality scale in DESI 2024

DESI Collaboration; B. Bahr-Kalus; D. Parkinson; K. Lodha; E. Mueller; E. Chaussidon; A. de Mattia; D. Forero-Sánchez; J. Aguilar; S. Ahlen; D. Bianchi; D. Brooks; T. Claybaugh; A. Cuceu; A. de la Macorra; P. Doel; A. Font-Ribera; E. Gaztañaga; S. Gontcho A. Gontcho; G. Gutierrez; K. Honscheid; D. Huterer; M. Ishak; R. Kehoe; S. Kent; D. Kirkby; T. Kisner; A. Kremin; O. Lahav; M. Landriau; L. Le Guillou; C. Magneville; M. Manera; P. Martini; A. Meisner; R. Miquel; J. Moustakas; S. Nadathur; N. Palanque-Delabrouille; W. J. Percival; F. Prada; I. Pérez-Ràfols; A. J. Ross; G. Rossi; L. Samushia; E. Sanchez; D. Schlegel; M. Schubnell; H. Seo; J. Silber; D. Sprayberry; G. Tarlé; B. A. Weaver; R. Zhou; H. Zou

doi:10.1103/yqm1-ybbv

Model-independent measurement of the matter-radiation equality scale in DESI 2024

B. Bahr-Kalus^1,2,3,4,*, D. Parkinson ^4,5,†, K. Lodha^4,5, E. Mueller⁶, E. Chaussidon⁷, A. de Mattia⁸, D. Forero-Sánchez⁹, J. Aguilar⁷, S. Ahlen¹⁰ et al. (DESI Collaboration)

S. Ahlen¹⁰, D. Bianchi^11,12, D. Brooks¹³, T. Claybaugh⁷, A. Cuceu⁷, A. de la Macorra¹⁴, P. Doel¹³, A. Font-Ribera¹⁵, E. Gaztañaga^16,17,18, S. Gontcho A. Gontcho⁷, G. Gutierrez¹⁹, K. Honscheid^20,21,22, D. Huterer^23,24, M. Ishak²⁵, R. Kehoe²⁶, S. Kent^19,27, D. Kirkby²⁸, T. Kisner⁷, A. Kremin⁷, O. Lahav¹³, M. Landriau⁷, L. Le Guillou²⁹, C. Magneville⁸, M. Manera^15,30, P. Martini^20,22,31, A. Meisner³², R. Miquel^15,33, J. Moustakas³⁴, S. Nadathur¹⁷, N. Palanque-Delabrouille^8,7, W. J. Percival^35,36,37, F. Prada³⁸, I. Pérez-Ràfols³⁹, A. J. Ross^20,31,22, G. Rossi⁴⁰, L. Samushia^41,42,43, E. Sanchez⁴⁴, D. Schlegel⁷, M. Schubnell^23,24, H. Seo⁴⁵, J. Silber⁷, D. Sprayberry³², G. Tarlé²⁴, B. A. Weaver³², R. Zhou⁷, and H. Zou⁴⁶ (DESI Collaboration)

¹INAF, Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
²Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
³INFN, Sezione di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
⁴Korea Astronomy and Space Science Institute, 776, Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea
⁵University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
⁶Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
⁷Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
⁸IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
⁹Institute of Physics, Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, Chemin Pegasi 51, CH-1290 Versoix, Switzerland
¹⁰Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 USA
¹¹Dipartimento di Fisica “Aldo Pontremoli,” Università degli Studi di Milano, Via Celoria 16, I-20133 Milano, Italy
¹²INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
¹³Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, United Kingdom
¹⁴Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad Universitaria, Ciudad de México Código Postal 04510, México
¹⁵Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Edifici Cn, Campus UAB, 08193, Bellaterra (Barcelona), Spain
¹⁶Institut d’Estudis Espacials de Catalunya (IEEC), c/Esteve Terradas 1, Edifici RDIT, Campus PMT-UPC, 08860 Castelldefels, Spain
¹⁷Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX, United Kingdom
¹⁸Institute of Space Sciences, ICE-CSIC, Campus UAB, Carrer de Can Magrans s/n, 08913 Bellaterra, Barcelona, Spain
¹⁹Fermi National Accelerator Laboratory, PO Box 500, Batavia, Illinois 60510, USA
²⁰Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210, USA
²¹Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210, USA
²²The Ohio State University, Columbus, 43210 Ohio, USA
²³Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, USA
²⁴University of Michigan, 500 South State Street, Ann Arbor, Michigan 48109, USA
²⁵Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
²⁶Department of Physics, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275, USA
²⁷Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA
²⁸Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
²⁹Sorbonne Université, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), FR-75005 Paris, France
³⁰Departament de Física, Serra Húnter, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
³¹Department of Astronomy, The Ohio State University, 4055 McPherson Laboratory, 140 W 18th Avenue, Columbus, Ohio 43210, USA
³²United States National Science Foundation National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, Arizona 85719, USA
³³Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys, 23, 08010 Barcelona, Spain
³⁴Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, New York 12211, USA
³⁵Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
³⁶Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5, Canada
³⁷Waterloo Centre for Astrophysics, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
³⁸Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, s/n, E-18008 Granada, Spain
³⁹Departament de Física, EEBE, Universitat Politècnica de Catalunya, c/Eduard Maristany 10, 08930 Barcelona, Spain
⁴⁰Department of Physics and Astronomy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
⁴¹Abastumani Astrophysical Observatory, Tbilisi, GE-0179, Georgia
⁴²Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506, USA
⁴³Faculty of Natural Sciences and Medicine, Ilia State University, 0194 Tbilisi, Georgia
⁴⁴CIEMAT, Avenida Complutense 40, E-28040 Madrid, Spain
⁴⁵Department of Physics and Astronomy, Ohio University, 139 University Terrace, Athens, Ohio 45701, USA
⁴⁶National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing, 100101, People’s Republic of China

^*Contact author: benedict.bahrkalus@inaf.it
^†Contact author: davidparkinson@kasi.re.kr

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Phys. Rev. D 112, 063553 – Published 24 September, 2025

DOI: https://doi.org/10.1103/yqm1-ybbv

Abstract

The peak of the matter power spectrum, known as the turnover (TO) scale, is determined by the horizon size at the time of matter-radiation equality. This scale can serve as a standard ruler, independent of other features in the matter power spectrum, such as baryon acoustic oscillations (BAO). Here, we present the first detection of the turnover in the galaxy autopower spectrum, utilizing the distribution of quasars and luminous red galaxies (LRG) measured by the Dark Energy Spectroscopic Instrument (DESI) during its first year of survey operations in a model-independent manner. To avoid confirmation bias, we first analyze the data using data blinding methods designed for the DESI baryon acoustic oscillation, redshift space distortion and scale-dependent bias signals. We measure the angle-averaged dilation distance $D_{V} (z = 1.651) = (38.1 \pm 2.5) r_{H}$ from the quasars and $D_{V} (z = 0.733) = (21.8 \pm 1.0) r_{H}$ from the LRG sample in units of the horizon $r_{H}$ at the matter-radiation-equality epoch. Combining these two constraints and assuming a flat $Λ CDM$ model with three standard neutrino species, we can translate this into a constraint of $Ω_{m} h^{2} = 0.13 9_{- 0.046}^{+ 0.036}$ . We can break the $Ω_{m} − H_{0}$ degeneracy with low-redshift distance measurements from type-Ia supernova (SN) data from $Pantheon +$ , we obtain a sound-horizon free estimate of the Hubble-Lemaître parameter of $H_{0} = {65.2}_{- 6.2}^{+ 4.9} km / s / Mpc$ , consistent with sound-horizon dependent DESI measurements. On the other hand, combining the DESI BAO and TO, we find a truly DESI-only measurement of $H_{0} = {74.0}_{- 3.5}^{+ 7.2} km / s / Mpc$ , in line with DESI-only full-shape results where the sound-horizon scale is marginalized out. This discrepancy in $H_{0}$ can be reconciled in a $w_{0} w_{a} CDM$ cosmology, where the combination of DESI BAO and TO data yields $H_{0} = 66.5 \pm 7.2 km / s / Mpc$ .

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Model-independent measurement of the matter-radiation equality scale in DESI 2024

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Model-independent measurement of the matter-radiation equality scale in DESI 2024

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