Key drivers of the preference for dynamic dark energy

Understand

Joint analysis of the baryon acoustic oscillations (BAO) measurement by the Dark Energy Spectroscopic Instrument (DESI) first data release, Type Ia supernovae (SNe) of the Dark Energy Survey Year 5 (DES5YR) release and cosmic microwave background (CMB) data favors a quintom-like dynamic dark energy model over the standard Lambda cold dark matter ($\Lambda$CDM) model at $3.9\sigma$ level (Adame et al.

• 2024).
• We confirm the previous finding in the literature that the preference for dynamic dark energy does not rely on the detailed modeling of CMB physics and remains at a similar significance level ($3.2\sigma$) when the full CMB likelihood is replaced by a CMB acoustic-oscillation angle ($\theta_\star$) prior and a baryon abundance ($\Omega_bh^2$) prior.
• The computationally efficient $\theta_\star$ and $\Omega_bh^2$ priors allow us to take a frequentist approach by comparing DES5YR SNe and DESI BAO with a large number ($\gtrsim 10^4$) of Planck-constrained $\Lambda$CDM simulations.