2025/03/04 by Purba Mukherjee, Anjan A. Sen, Mukherjee, Purba +1 · 4 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Computer and information sciences #FOS: Physical sciences #Gamma-ray bursts and supernovae #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #High Energy Physics - Theory (hep-th) #Machine Learning (cs.LG)
paper · pdf · doi:10.48550/arxiv.2503.02880
openalex publication_date 2025/03/04 · openalex created_date 2025/10/13 · openalex updated_date 2026/07/28
We perform a model-independent reconstruction of the angular diameter distance (DA) using the Multi-Task Gaussian Process (MTGP) framework with DESI-DR1 BAO and DES-SN5YR datasets. We calibrate the comoving sound horizon at the baryon drag epoch rd to the Planck best-fit value, ensuring consistency with early-universe physics. With the reconstructed DA at two key redshifts, z∼ 1.63 (where DA′ =0) and at z∼ 0.512 (where DA′ = DA), we derive the expansion rate of the Universe H(z) at these redshifts. Our findings reveal that at z∼ 1.63, the H(z) is fully consistent with the Planck-2018 ΛCDM prediction, confirming no new physics at that redshift. However, at z ∼ 0.512, the derived H(z) shows a more than 5σ discrepancy with the Planck-2018 ΛCDM prediction, suggesting a possible breakdown of the ΛCDM model as constrained by Planck-2018 at this lower redshift. This emerging ∼ 5σ tension at z∼ 0.512, distinct from the existing ``Hubble Tension'', may signal the first strong evidence for new physics at low redshifts.