Advancements in Dark Matter Research: New Insights from DESI and CMB Data

Recent research utilizing data from the Dark Energy Spectroscopic Instrument, or DESI, alongside cosmic microwave background data, has provided significant insights into dark matter and dark energy. A study published on ArXiv titled 'Clustering in dynamical dark energy: observational constraints from DESI, CMB, and supernovae' investigates the clustering properties of dynamical dark energy using the latest cosmological observations. The research utilizes baryon acoustic oscillations from DESI's second data release, combined with Planck 2018 CMB data and the Union3 supernova sample. The findings suggest that the effective sound speed of dark energy remains unconstrained for the $w$CDM model but indicates a mean value of about 0.3 to 0.4 for the $w_0w_a$CDM model, pointing towards a mild preference for dynamical dark energy while still showing no significant evidence for clustering. Additionally, the equation of state shows a deviation from the standard $ ext{Lambda}CDM$ model, reaching a significance of $3.42$ sigma, which raises the need for future observations for clearer insights.

Further analysis from another paper titled 'Robust evidence for dynamical dark energy in light of DESI DR2 and joint ACT, SPT, and Planck data' emphasizes this trend, suggesting a significant preference for dynamical dark energy that has transitioned from phantom-like behavior in the past to quintessence-like behavior today. This research conducted a comprehensive analysis across various dark energy parameterization models, concluding that the evidence for dynamical dark energy remains robust, particularly when combining data from DESI, ACT, SPT, and Planck. The quantifiable parameters obtained, such as $w_0 = -0.785 \pm 0.047$ and $w_a = -0.43^{+0.10}_{-0.09}$, highlight a significant deviation from the $ ext{Lambda}CDM$ values, providing evidence for dynamical dark energy at the $4.2$ sigma level.

Additional exploration into axion dark energy, as reported in 'Cosmology of axion dark energy in supersymmetric models and constraints on high scale parameters,' posits that dark energy may be represented by an ultralight axionic field. The study indicates better fitting with cosmological data when considering multiple cosine terms rather than a single term, offering constraints on the axion decay constant that align with string theory predictions. This work also suggests a feeble dark energy-dark matter interaction, which may have implications for the Hubble tension, using DESI data to reinforce these findings. Lastly, the paper 'Kinetic Mixing and the Phantom Illusion: Axion-Dilaton Quintessence in Light of DESI DR2' discusses the possibility that dark energy is not a constant but rather dynamic, supported by DESI BAO analyses. The findings show that the equation of state may have undergone a phantom crossing, further supporting the dynamical nature of dark energy through the kinetically mixed axion-dilaton model, which provides a robust framework for explaining these phantom-like signatures observed in recent data. As these studies collectively advance our understanding of dark matter and dark energy, they highlight the need for continued research and observation to clarify these complex phenomena.