Testing the distance duality relation using type Ia supernovae and ultracompact radio sources

TL;DR

This study tests the cosmic distance duality relation's validity using supernovae and radio sources in a model-independent way, finding results consistent with no deviation within uncertainties.

Contribution

It introduces a model-independent method to test the distance duality relation using standard candles and rulers, with two parameterizations of potential deviations.

Findings

Results are consistent with the distance duality relation within uncertainties.

No significant deviation from the standard relation was detected.

Method is independent of cosmological model assumptions.

Abstract

We test the possible deviation of the cosmic distance duality relation $D_A(z)(1+z)^2/D_L(z)\equiv 1$ using the standard candles/rulers in a fully model-independent manner. Type-Ia supernovae are used as the standard candles to derive the luminosity distance $D_L(z)$, and ultra-compact radio sources are used as the standard rulers to obtain the angular diameter distance $D_A(z)$. We write the deviation of distance duality relation as $D_A(z)(1+z)^2/D_L(z)=\eta(z)$. Specifically, we use two parameterizations of $\eta(z)$, i.e. $\eta_1(z)=1+\eta_0 z$ and $\eta_2(z)=1+\eta_0 z/(1+z)$. The parameter $\eta_0$ is obtained using the Markov chain Monte Carlo methods by comparing $D_L(z)$ and $D_A(z)$ at the same redshift. The best-fitting results are $\eta_0=-0.06\pm 0.05$ and $-0.18\pm 0.16$ for the first and second parameterizations, respectively. Our results depend on neither the cosmological models, nor the matter contents or the curvature of the universe.