Missing components in ΛCDM from DESI Y1 baryonic acoustic oscillation measurements: Insights from redshift remapping

¹ Instituto de Astrofisica de Andalucia (CSIC), E18008 Granada, Spain
² DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200 Copenhagen, Denmark
³ Carreterra Méico-Toluca S/N, La Marquesa, Ocoyoacac, Edo. de México C.P. 52750, Mexico
⁴ University of Michigan, 500 S. State Street, Ann Arbor, MI 48109, USA
⁵ Department of Astronomy & Astrophysics, University of Chicago, Chicago, IL 60637, USA
⁶ Kavli Institute for Cosmological Physics, Chicago, IL 60637, USA
⁷ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
⁸ Physics Dept., Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
⁹ Department of Physics & Astronomy, University of Rochester, 206 Bausch and Lomb Hall, P.O. Box 270171 Rochester, NY 14627-0171, USA
¹⁰ Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano, Via Celoria 16, I-20133 Milano, Italy
¹¹ INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
¹² Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
¹³ Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica, Ciudad Universitaria, Cd. de México C. P. 04510, Mexico
¹⁴ Institut d’Estudis Espacials de Catalunya (IEEC), c/ Esteve Terradas 1, Edifici RDIT, Campus PMT-UPC, 08860 Castelldefels, Spain
¹⁵ Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX, UK
¹⁶ Fermi National Accelerator Laboratory, PO Box 500 Batavia, IL 60510, USA
¹⁷ Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
¹⁸ The Ohio State University, Columbus, 43210 OH, USA
¹⁹ Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
²⁰ Department of Physics, The University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080, USA
²¹ National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory, USA
²² Department of Physics and Astronomy, University of California, Irvine 92697, USA
²³ Sorbonne Université, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), FR-75005 Paris, France
²⁴ Department of Astronomy & Astrophysics, University of Toronto, Toronto, ON M5S 3H4, Canada
²⁵ Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Edifici Cn, Campus UAB, 08193 Bellaterra (Barcelona), Spain
²⁶ Departament de Física, Serra Húnter, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
²⁷ NSF NOIRLab, 950 N. Cherry Ave., Tucson, AZ 85719, USA
²⁸ Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys, 23, 08010 Barcelona, Spain
²⁹ Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211, USA
³⁰ Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX, UK
³¹ Department of Physics and Astronomy, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
³² Perimeter Institute for Theoretical Physics, 31 Caroline St. North, Waterloo, ON N2L 2Y5, Canada
³³ Waterloo Centre for Astrophysics, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
³⁴ Departament de Física, EEBE, Universitat Politècnica de Catalunya, c/Eduard Maristany 10, 08930 Barcelona, Spain
³⁵ Department of Physics and Astronomy, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
³⁶ CIEMAT, Avenida Complutense 40, E-28040 Madrid, Spain
³⁷ Department of Physics & Astronomy, Ohio University, 139 University Terrace, Athens, OH 45701, USA
³⁸ National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Rd., Chaoyang District, Beijing 100012, P.R. China

^⋆ Corresponding author: efdez@iaa.es

Received: 4 April 2025
Accepted: 1 August 2025

Abstract

Aims. We explore transformations of the Friedman-Lemaître-Robertson-Walker (FLRW) metric and cosmological parameters that align with observational data while aiming to gain insights into potential extensions of standard cosmological models.

Methods. We modified the FLRW metric by introducing a scaling factor, e^2Θ(a)–the cosmological scaling function (CSF), which alters the standard relationship between cosmological redshift and the cosmic scale factor without affecting angular measurements or cosmic microwave background (CMB) anisotropies. Using data from DESI Year 1, Pantheon+ supernovae, and the Planck CMB temperature power spectrum, we constrained both the CSF and cosmological parameters through a Markov chain Monte Carlo approach.

Results. Our results indicate that the CSF model fits observational data with a lower Hubble constant (although it is compatible with the value given by Planck 2018 within 1σ) and is predominantly dark matter dominated. Additionally, the CSF model produces temperature and lensing power spectra similar to those predicted by the standard model, though with lower values in the CSF model at large scales. We also checked that when fitting a CSF model without dark energy to the data, we obtain a more negative conformal function. This suggests that the CSF model may offer hints about missing elements and opens up a new avenue for exploring physical interpretations of cosmic acceleration.