Does DESI 2024 Confirm $\hat{I}›$CDM?

Abstract

We demonstrate that a $\sim 2\ddot{I}ƒ$ discrepancy with the Planck-$\hat{I}›$CDM cosmology in DESI Luminous Red Galaxy (LRG) data in the redshift range $0.4<z<0.6$ with effective redshift $z_{\text{eff}}=0.51$ translates into an unexpectedly large $\hat{I}{\text{c◯}}_m$ value, $\hat{I}{\text{c◯}}_m=0.67_{-0.17}^{+0.18}$. We independently confirm that this anomaly drives the preference for $w_0>-1$ in DESI data \textit{alone} confronted to the $w_0{w}_a$CDM model. Given that LRG data at $z_{\text{eff}}=0.51$ 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 $\hat{I}{\text{c◯}}_m$ trend with effective redshift at higher redshifts. We estimate the current significance of the latter in DESI data at $\sim 1.8\ddot{I}ƒ$ and comment on how it dovetails with independent observations. It is imperative to understand what makes DESI LRG data at $z_{\text{eff}}=0.51$ an outlier when it comes to $\hat{I}{\text{c◯}}_m$ determinations.

5 pages, 3 figures; v2 comments added, references updated; v3 to appear in JHEAP