📝 SummarXiv

Abstract

We perform a consistency check of DESI DR2 BAO constraints ($D_M/r_d, D_H/r_d)$ by reconstructing the same quantities from DES supernovae (SNe) in bins with the same effective redshift $z_{\textrm{eff}}$. We find that the ratio of $D_M/r_d$ values are consistent with a horizontal, thus confirming that the distance duality relation holds up to calibration. However, the $D_H/r_d$ ratio shows a decreasing trend with $z_{\textrm{eff}}$ at $2.3 \sigma$ to $2.5 \sigma$ that cannot be explained by physics. We demonstrate that the result does not depend on the choice of cosmological model, but the radius of the sound horizon $r_d$ has a much greater influence. Studying ratios of $D_H/r_d$ is a stronger test than the distance duality relation, and the rejection of a horizontal confirms systematics in either DESI BAO or DES SNe. Claims of new physics based on combined data still have rudimentary hurdles to clear.