2025/05/14 by M. N. Abedin, Luis A. Escamilla, Abedin, Mazaharul +7 · 11 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Scientific Research and Discoveries
paper · doi:10.48550/arxiv.2505.09470
openalex publication_date 2025/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a non-zero equation of state (EoS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled as pressureless dust with w\rm DM = 0, an assumption that aligns with large-scale structure formation, supports the empirical success of the ΛCDM model, and simplifies cosmological modeling. However, there is no fundamental reason to exclude a non-zero w\rm DM from the cosmological framework. In this work, we explore this possibility through non-parametric and parametric reconstructions based on Gaussian Process Regression. The reconstructions use Hubble parameter measurements from Cosmic Chronometers (CC), the Pantheon+ sample of Type Ia supernovae, and Baryon Acoustic Oscillation (BAO) data from DESI DR1 and DR2. Our findings suggest that a dynamical EoS for DM, although only mildly supported statistically, cannot be conclusively ruled out. Notably, we observe a mild tendency (∼ 1σ) toward a negative w\rm DM at the present epoch, which is most likely due to inconsistencies between the BAO data from DESI and other datasets.