$\Lambda$CDM model against cosmography: A possible deviation after DESI 2024

TL;DR

This study tests the flat-$\\Lambda$CDM model against cosmographic data using recent DESI BAO and SNIa observations, revealing potential tensions when combining Planck and Cepheid priors, suggesting possible new physics or systematic errors.

Contribution

It provides a comprehensive analysis of the flat-$\Lambda$CDM model with recent observational data, highlighting tensions under combined priors that challenge the model's consistency.

Findings

Full consistency with individual data sets

Tensions arise when combining Planck and Cepheid priors

Standard model struggles to reconcile high-redshift and local measurements

Abstract

In this study, we present an analysis of the standard flat-$\Lambda$CDM model using a cosmographic approach, incorporating recent DESI BAO observations and Supernovae Type Ia catalogues (SNIa), including the DES-SN5YR and Pantheon+ compilations. We find full consistency between the standard model and the cosmographic approach when considering DESI BAO and SNIa catalogues independently. When combining DESI BAO with SNIa data, we examine the impact of the Planck prior on the sound horizon at the drag epoch, $r_d$, and the Cepheid prior on the absolute magnitude, $M$. Applying the Planck prior on $r_d$ alone yields an $H_0$ value consistent with the Planck measurement, while applying the Cepheid prior on $M$ alone results in an $H_0$ value consistent with the SH0ES measurement. Without any priors, the $H_0$ value obtained has a large error margin, reconciling the Planck and SH0ES measurements. In all cases where individual priors are applied, we observe no significant tension between the flat-$\Lambda$CDM model and the cosmographic approach. However, when both Planck and Cepheid priors are applied simultaneously, significant tensions arise between the model and cosmography. This tension is even more pronounced when excluding LRG1 and LRG2 from the DESI measurements. These results indicate that the standard model cannot simultaneously reconcile high-redshift Planck CMB observations and local Cepheid measurements. This discrepancy supports the possibility of new physics beyond the standard model or, alternatively, the presence of unrecognized systematic errors in the observational data.