Testing cosmic opacity from SNe Ia and Hubble parameter through three cosmological-model-independent methods

TL;DR

This study tests the universe's transparency using recent Hubble parameter data and SNe Ia samples through three independent, model-free methods, finding evidence supporting a transparent universe.

Contribution

It introduces three novel, model-independent methods to compare distance measures and assess cosmic opacity using observational data.

Findings

Results are consistent across methods and parameterizations.

Data supports a universe that is transparent.

No significant cosmic opacity detected.

Abstract

We use the newly published 28 observational Hubble parameter data ($H(z)$) and current largest SNe Ia samples (Union2.1) to test whether the universe is transparent. Three cosmological-model-independent methods (nearby SNe Ia method, interpolation method and smoothing method) are proposed through comparing opacity-free distance modulus from Hubble parameter data and opacity-dependent distance modulus from SNe Ia . Two parameterizations, $\tau(z)=2\epsilon z$ and $\tau(z)=(1+z)^{2\epsilon}-1$ are adopted for the optical depth associated to the cosmic absorption. We find that the results are not sensitive to the methods and parameterizations. Our results support a transparent universe.