Dynamical dark energy from an ultralight axion

2025/03/23 by Hoang Nhan Luu, Luu, Hoang Nhan, Yu-Cheng Qiu +3 · 10 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #High Energy Physics - Phenomenology (hep-ph)

paper · pdf · doi:10.48550/arxiv.2503.18120

openalex publication_date 2025/03/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Recently the Dark Energy Survey (DES) Collaboration presented evidence that the equation of state w of the dark energy is varying, or w ≃ -0.948 if it is constant. In either case, the dark energy cannot be due to a cosmological constant alone. Here we study an ultralight axion (or axion-like particle) with mass m_ϕ≃ 2 × 10^-33 eV that has properties that can explain the new w measurement. In particular, w≥ -1 and a negative cosmological constant Λ< 0 is preferred in this model. We also present a simple formula for w for the model to ease data fitting.

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