Interpreting DESI's evidence for evolving dark energy
By Marina Cortês, Andrew R. Liddle. Journal of Cosmology and Astroparticle Physics, 2024
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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.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/96d1bc49368239ba3aaefe5693c1d9fdddb14d57
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Citations in the corpus
- Robust preference for Dynamical Dark Energy in DESI BAO and SN measurements (2024, background): “At its core, the problem is that different combinations of late-time cosmic parameters can be adjusted in such a way that the acoustic angular scale θ s – determined by the ratio of the comoving sound horizon at recombination to the comoving distance to last scattering – remains constant if both…”
- Assessing observational constraints on dark energy (2024, unknown): “[26], we have shown that it is not just reasonable but crucially important for observational analyses to include combinations of ( w 0 , w a ) satisfying w 0 + w a − 1 in their priors with high credence.”