Model-independent constraints on the cosmic opacity

TL;DR

This study constrains cosmic opacity using model-independent methods by comparing expansion rate data and supernovae observations, finding consistency with a transparent universe within current observational uncertainties.

Contribution

It provides the first model-independent constraints on cosmic opacity using $H(z)$ data and supernovae, accounting for different light-curve fitters and spatial curvature bounds.

Findings

A transparent universe aligns with the largest data sample.

SDSS data is compatible with transparency at less than 1.5 sigma.

Results are robust across different supernova light-curve fitters.

Abstract

We use current measurements of the expansion rate $H(z)$ and cosmic background radiation bounds on the spatial curvature of the Universe to impose cosmological model-independent constraints on cosmic opacity. To perform our analyses, we compare opacity-free distance modulus from $H(z)$ data with those from two supernovae Ia compilations: the Union2.1 plus the most distant spectroscopically confirmed SNe Ia (SNe Ia SCP-0401 $z=1.713$) and two Sloan Digital Sky Survey (SDSS) subsamples. The influence of different SNe Ia light-curve fitters (SALT2 and MLCS2K2) on the results is also verified. We find that a completely transparent universe is in agreement with the largest sample in our analysis (Union 2.1 plus SNe Ia SCP-0401). For SDSS sample a such universe it is compatible at $< 1.5\sigma$ level regardless the SNe Ia light-curve fitting used.