Understand
We demonstrate that the constraints on the evolution of dark energy implemented by the DESI collaboration may be insufficient or incomplete using their own BAO data.
- Using large enough prior ranges for the present-day equation of state of dark energy $\omega_0$ and amplitude of dark energy evolution $\omega_a$, we obtain the complete $1\,\sigma$ and $2\,\sigma$ constraints $\omega_0=1.04^{+0.91+2.00}_{-1.00-1.90}$ and $\omega_a=-7.4^{+3.8+6.8}_{-3.2-7.3}$ indicating a beyond $2\,\sigma$ preference of quintessence-like dark energy today and an evidence of evolving dark energy at beyond $2\,\sigma$ CL, respectively.
- Our results are different from $\omega_0=-0.55^{+0.39}_{-0.21}$ and the $2\,\sigma$ upper limit $\omega_a<-1.32$ reported by the DESI collaboration \cite{DESI:2024mwx}.
- Employing a data combination of cosmic microwave background, DESI BAO and type Ia supernova, we obtain the $1\,\sigma$, $2\,\sigma$ and $3\,\sigma$ constraints $\omega_0=-0.707^{+0.089+0.18+0.24}_{-0.089-0.17-0.22}$ and $\omega_a=-1.09^{+0.38+0.67+0.82}_{-0.31-0.72-1.00}$, which reveals a $\sim4\,\sigma$ evidence of dynamical dark energy when the redshift $z\lesssim0.1$.