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 magnitude $M_B$ and the comoving sound horizon at the baryon drag epoch $r_d$. {This could reduce some systematics in the observed data, if present}. 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 $\lesssim! 1\sigma$ across their redshift ranges, whereas the DES-Y5 tension is $\gtrsim3\sigma$ near $z=1$. 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.