Calibration-independent consistency test of DESI DR2 BAO and SNIa

Abstract

We investigate the consistency between DESI DR2 BAO and three SNIa datasets, Pantheon+, Union3, and DES-Y5. Our consistency test is calibration-independent since it is independent of cosmological nuisance parameters such as the absolute peak magnitudeMB and the comoving sound horizon at the baryon drag epochrd. Importantly, the test is also model-agnostic, independent of any model of dark energy or modified gravity. We define a tension parameter to quantify tension across different datasets compared to DESI DR2 BAO. The Pantheon+ and Union3 data have tension ≲ 1σ across their redshift ranges, whereas the DES-Y5 tension is ≳ 3σ nearz= 1. This hints that DES-Y5 data has significant offset values for redshifts close to 1, compared to the other SNIa datasets. Since this consistency test is independent of cosmological nuisance parameters, the tension is minimal: other consistency tests involving differences in nuisance parameters may show greater tension.