A New $sim 5sigma$ Tension at Characteristic Redshift from DESI DR1 and DES-SN5YR observations
🤖 AI Summary
This work addresses the >5σ tension between low-redshift (z ∼ 0.512) H(z) measurements and Planck 2018 ΛCDM predictions—a critical challenge to standard cosmology. We propose a model-independent multi-task Gaussian process (MTGP) method that jointly reconstructs the angular diameter distance D_A from DESI DR1 baryon acoustic oscillation (BAO) and DES-SN5YR supernova data, then derives H(z) using the Planck-calibrated sound horizon scale r_d. Our reconstruction yields the first >5σ deviation from ΛCDM at z ∼ 0.512, while showing full consistency with the model at z ∼ 1.63—strongly disfavoring dominant systematic errors. Unlike the well-known H₀ tension, this low-redshift H(z) anomaly may constitute the earliest robust evidence for new physics, such as evolving dark energy or modified gravity, thereby opening a novel observational dimension for testing the ΛCDM paradigm.
Application Category
📝 Abstract
We perform a model-independent reconstruction of the angular diameter distance ($D_{A}$) 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 $r_d$ to the Planck best-fit value, ensuring consistency with early-universe physics. With the reconstructed $D_A$ at two key redshifts, $zsim 1.63$ (where $D_{A}^{prime} =0$) and at $zsim 0.512$ (where $D_{A}^{prime} = D_{A}$), we derive the expansion rate of the Universe $H(z)$ at these redshifts. Our findings reveal that at $zsim 1.63$, the $H(z)$ is fully consistent with the Planck-2018 $Lambda$CDM prediction, confirming no new physics at that redshift. However, at $z sim 0.512$, the derived $H(z)$ shows a more than $5sigma$ discrepancy with the Planck-2018 $Lambda$CDM prediction, suggesting a possible breakdown of the $Lambda$CDM model as constrained by Planck-2018 at this lower redshift. This emerging $sim 5sigma$ tension at $zsim 0.512$, distinct from the existing ``Hubble Tension'', may signal the first strong evidence for new physics at low redshifts.
Problem
Research questions and friction points this paper is trying to address.
Reconstructs angular diameter distance using DESI-DR1 and DES-SN5YR data.
Calibrates comoving sound horizon to Planck best-fit value for consistency.
Identifies a 5σ discrepancy in H(z) at z∼0.512, suggesting new physics.
Innovation
Methods, ideas, or system contributions that make the work stand out.
Model-independent reconstruction using MTGP framework
Calibration of sound horizon to Planck best-fit value
Derivation of expansion rate at key redshifts
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