Testing Cosmic Distance Duality Relation and Transparency with DESI DR2

TL;DR

This study tests the Cosmic Distance Duality Relation and cosmic transparency using DESI DR2 data, revealing that methodological choices significantly influence results, with no evidence of deviation from the standard cosmological model.

Contribution

It introduces a comparative analysis of reconstruction methods for testing the CDDR, highlighting the impact of methodology on systematic uncertainties in cosmological measurements.

Findings

Reconstruction method choice greatly affects test outcomes.

Marginalization has negligible impact on results.

Cosmic opacity tests support the validity of the CDDR.

Abstract

The Cosmic Distance Duality Relation (CDDR) is a basic relation of standard cosmology. This work tests the CDDR and cosmic transparency using angular diameter distances from DESI DR2, luminosity distances from Pantheon+, and direct measurements of the Hubble parameter. First, we use two redshift matching reconstruction method, the Gaussian Process Regression (GPR) and Control Points Interpolating (CPI) finding that the results are highly dependent on the cosmological prior choose which relates to Hubble tension. We then estimate parameters for several phenomenological models, comparing reconstruction methods and the effect of marginalization. The results show that marginalization has no significant impact, but the choice of reconstruction method is highly influential, highlighting methodology as a primary source of systematic uncertainty. Furthermore, our test for cosmic opacity rules out cosmic dust and provides auxiliary support for the validity of the CDDR. Therefore, we conclude that the CDDR itself exhibits no significant deviation, but different redshift matching methods strongly affect the results, and some singular results are more likely attributed to supernova calibration.