Mustapha Ishak – Persistent Evidence for Dynamical Dark Energy from Different Datasets

Research Talk | Cosmology from Home 2026 https://www.cosmologyfromhome.com/ Abstract: Recent cosmological observations favor dynamical dark energy (DDE) with a time-evolving equation of state over a cosmological constant, Lambda, as a driver of cosmic acceleration. We present a comprehensive analysis using a systematic dataset-exclusion study showing a preference trend for DDE that persists beyond any specific dataset. We use Baryon Acoustic Oscillation (BAO), Cosmic Microwave Background (CMB) with and without lensing, supernova (SN), prioritizing the recently recalibrated compilations, and cross-correlations between galaxy positions and galaxy lensing. We use pairs or trios of datasets where we exclude one type of dataset each time and categorize them as ``NO SN'', ``NO CMB'' and ``NO BAO'' combinations. In all cases, we find that the data combinations favor DDE over LambdaCDM, with significances reaching 3.1-sigma without any SN, 2.2-sigma without any CMB, and 1.8-sigma without any BAO. The trend remains even when DESI BAO is replaced by DES BAO, yielding 2.5-sigma. Combining BAO, CMB and SN sets gives consistent significance levels of 3.3-sigma to 3.4-sigma. While we remain cautious as we wait for incoming data, the overall pattern of evidence provides validation of the trend beyond any single type of dataset and its associated systematics. The persistence of the trend across datasets presents a compelling overall portrait in favor of dynamical dark energy over a cosmological constant, and constitutes a persistent challenge to the LCDM model's reign.