Does DESI 2024 confirm ΛCDM?
Eoin Ó Colgáin, Maria Giovanna Dainotti, Salvatore Capozzıello, Saeed Pourojaghi, M. M. Sheikh-Jabbari, Dejan Stojković
Abstract
We demonstrate that a ∼ 2 σ discrepancy with the Planck-ΛCDM cosmology in DESI Luminous Red Galaxy (LRG) data in the redshift range 0.4 < z < 0.6 with effective redshift z eff = 0.51 translates into an unexpectedly large Ω m value, Ω m = 0.67 − 0.17 + 0.18 . We independently confirm that this anomaly drives the preference for w 0 > − 1 in DESI data alone confronted to the w 0 w a CDM model. Given that LRG data at z eff = 0.51 is at odds with Type Ia supernovae in overlapping redshifts, we expect that this anomaly will decrease in statistical significance with future DESI data releases leaving an increasing Ω m trend with effective redshift at higher redshifts. We estimate the current significance of the latter in DESI data at ∼ 1.8 σ and comment on how it dovetails with independent observations. It is imperative to understand what makes DESI LRG data at z eff = 0.51 an outlier when it comes to Ω m determinations.