Year: 2026
Type: article
Abstract: We investigate potential deviations from cold dark matter (CDM) using the latest Baryon Acoustic Oscillations (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI). Analyzing DESI data alone constrains the dark matter equation of state parameter w dm = − 0 . 042 − 0.024 + 0.047 , revealing a mild preference for non-cold dark matter. This preference strengthens significantly in combined analyses, but reveals a striking tension in the inferred w dm values from observations of different nature. The DESI+DESY5 combination yields w dm = − 0.084 ± 0.035 , excluding CDM ( w dm = 0 ) at 2.4 σ significance. In contrast, Planck+DESI gives w dm = 0.00077 ± 0.00038 , differing from concordance model at 2 σ significance. The non-vanishing w dm preference is particularly driven by low-redshift BAO measurements ( z < 1.1), while higher redshift data remain consistent with ΛCDM. The preference for non-cold dark matter is more pronounced in DESI compared to the previous BAO surveys. All dataset combinations show significant improvement over the ΛCDM paradigm, providing preference for non-cold dark matter scenario except DESI+DESY3+DES-DOV case.
Source: Physics Letters B
Authors: Utkarsh Kumar, Abhijith Ajith, Amresh Verma
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Funder: University of Ottawa
OpenAlex ID: W7203549629