M. Cortês, A. R. Liddle
Abstract
The latest results on baryon acoustic oscillations from DESI (Dark Energy Spectroscopic Instrument), when combined with cosmic microwave background and supernova data, show indications of a deviation from a cosmological constant in favour of evolving dark energy. Use of a pivot scale for the equation of state w shows that this evidence is concentrated in the derivative of w rather than its mean offset from -1, indicating a new cosmic coincidence where the mean equation of state matches that of the ΛCDM model precisely in the region probed by the observations. An equivalent way to express this is to say that the dark energy hits the maximum value that it will ever achieve within the observed window. We argue that conclusions on dark energy evolution are strongly driven by the assumed parameter priors and that this coincidence, which we are naming the PhantomX coincidence (where X stands for crossing), may be a signature of this.
Keywords
dark energy theory, Bayesian reasoning, dark energy experiments
Journal of Cosmology and Astroparticle Physics
Volume 12, Issue 007, Page 10
2024 December
