What question did this study set out to answer?

This research aims to explore a new cosmological model, COCM, and its effects on the expansion rate H(z).

May 13, 2026Open Access

Evidence for a periodic modulation of H(z) independent of dynamical dark energy in DESI DR2 data

Key Points

This research aims to explore a new cosmological model, COCM, and its effects on the expansion rate H(z).
Extended COCM model fitting to H(z) data from DESI DR1 and DR2 with a total of 38 samples combined with cosmic chronometers.
Statistical comparisons made against standard models like LCDM and w0waCDM through Delta_chi2 analysis and MCMC methods.
COCM shows significant improvement over LCDM with Delta_chi2=10.1 for DR1 (p=0.018) and Delta_chi2=194.6 for DR2.
COCM outperforms w0waCDM with Delta_chi2=87.7, emphasizing model robustness.
MCMC analysis indicates parameter A0=0.177±0.019 at 9.4-sigma, providing strong evidence for the model's validity.

Abstract

We present the Concentric Orbital Cosmological Model (COCM), an extension of LCDM in which the observable universe is a ring Rₙ in Keplerian orbit around a cosmological focus C₀, interpreted as a dynamic p-brane in a higher-dimensional bulk. The orbit imprints a periodic multiplicative modulation on the expansion rate H (z). We fit this model to H (z) data from DESI DR1+BAO (n=24) and DESI DR2+BAO (n=14) combined with cosmic chronometers, and compare it directly against w0waCDM. Key results: (1) COCM improves over LCDM with Deltachi2=10. 1 (p=0. 018) in DR1 and Deltachi2=194. 6 in DR2. (2) COCM outperforms w0waCDM by Deltachi2=87. 7. (3) COCM+w0wa improves over w0wa alone by Deltachi2=126. 1 (p<0. 0001): the two signals are statistically independent. (4) Bootstrap significance rises from 1. 2-sigma (DR1) to 1. 7-sigma (DR2). (5) MCMC analysis gives A0=0. 177+/-0. 019 in COCM+w0wa at 9. 4-sigma (68% CI: 0. 158, 0. 193). (6) The modulation naturally accounts for ~87% of the Hubble tension (4. 86 of 5. 6 km/s/Mpc) without additional free parameters. This is the fifth paper in the COCM research programme. Related works: P1: DOI 10. 5281/zenodo. 19950582P2: DOI 10. 5281/zenodo. 19991607P3: DOI 10. 5281/zenodo. 20090596P4: DOI 10. 5281/zenodo. 20096465NT: DOI 10. 5281/zenodo. 20104113

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