Testing cosmic opacity with the combination of strongly lensed and unlensed supernova Ia

Understand

In this paper, we present a scheme to investigate the opacity of the Universe in a cosmological-model-independent way, with the combination of current and future measurements of type Ia supernova sample and galactic-scale strong gravitational lensing systems with SNe Ia acting as background sources.

• The observational data include the current newly-compiled SNe Ia data (Pantheon sample) and simulated sample of SNe Ia observed by the forthcoming Large Synoptic Survey Telescope (LSST) survey, which are taken for luminosity distances ($D_L$) possibly affected by the cosmic opacity, as well as strongly lensed SNe Ia observed by the LSST, which are responsible for providing the observed time-delay distance ($D_{\Delta t}$) unaffected by the cosmic opacity.
• Two parameterizations, $\tau(z)=2\beta z$ and $\tau(z)=(1+z)^{2\beta}-1$ are adopted for the optical depth associated to the cosmic absorption.
• Focusing on only one specific type of standard cosmological probe, this provides an original method to measure cosmic opacity at high precision.