[2404.13833]
Deng Wang
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 $ω_0$ and amplitude of dark energy evolution $ω_a$, we obtain the complete $1\,σ$ and $2\,σ$ constraints $ω_0=1.04^{+0.91+2.00}_{-1.00-1.90}$ and $ω_a=-7.4^{+3.8+6.8}_{-3.2-7.3}$ indicating a beyond $2\,σ$ preference of quintessence-like dark energy today and an evidence of evolving dark energy at beyond $2\,σ$ CL, respectively. Our results are different from $ω_0=-0.55^{+0.39}_{-0.21}$ and the $2\,σ$ upper limit $ω_a<-1.32$ 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 $1\,σ$, $2\,σ$ and $3\,σ$ constraints $ω_0=-0.707^{+0.089+0.18+0.24}_{-0.089-0.17-0.22}$ and $ω_a=-1.09^{+0.38+0.67+0.82}_{-0.31-0.72-1.00}$, which reveals a $\sim4\,σ$ evidence of dynamical dark energy when the redshift $z\lesssim0.1$. We verify that the BAO data point from luminous red galaxies at the effective redshift $z_{\rm eff}=0.51$ hardly affects the joint constraint from the data combination of cosmic microwave background, DESI BAO and type Ia supernova. We also point out the shortcomings and advantages of the binning method widely used in cosmological analyses.