Reconstruction of dark energy using DESI DR2

Abstract Using a model-independent Gaussian process (GP) method to reconstruct the dimensionless luminosity distance D and its derivatives, we derive the evolution of the dimensionless Hubble parameter E , the deceleration parameter q , and the state parameter w of dark energy. We utilize the PantheonPlus, SH0ES, and Gamma Ray Burst (GRB) data to derive the dimensionless luminosity distance D . Additionally, we employ observational H ( z ) data (OHD) and baryon acoustic oscillations (BAO) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) to obtain the first derivative of the dimensionless luminosity distance D ′ . To obtain the reconstructed D and D ′ , we utilize the fiducial value from each dataset, with particular emphasis on the varying H 0 . According to the reconstruction results obtained from PantheonPlus+SH0ES+GRB+OHD and PantheonPlus+SH0ES+GRB+OHD+DESI data, we find that E is consistent with the predictions of the ΛCDM model at a 2 σ confidence level within the redshift range of z < 2. However, the reconstruction results for q exhibit deviations from the ΛCDM model in the range of z < 0.3. Furthermore, we observe that the mean value of w exhibits evolving behavior, transiting from w < −1 to w > −1 around z wt = 0.46 4 − 0.120 + 0.235 . Combining data from DESI DR2 can slightly enhance the accuracy of our constraints.