Testing Cosmic Opacity with the Combination of Strongly Lensed and Unlensed Supernova Ia

Abstract

In this paper, we present a scheme to investigate the opacity of the Universe in a cosmological-modelindependent 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 ∆t ) unaffected by the cosmic opacity. Two parameterizations, τ (z) = 2βz and τ (z) = (1 + z) 2β − 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. Working on the simulated sample of strongly lensed SNe Ia observed by the LSST in 10 year z-band search, our results show that, with the combination of the current newly-compiled SNe Ia data (Pantheon sample), there is no significant deviation from the transparency of the Universe at the current observational data level. Moreover, strongly lensed SNe Ia in a 10 year LSST z-band search would produce more robust constraints on the validity of cosmic transparency (at the precision of ∆β = 10 −2 ), with a larger sample of unlensed SNe Ia detected in future LSST survey. We have also discussed the ways in which our methodology could be improved, with the combination of current and future available data in gravitational wave (GW) and electromagnetic (EM) domain. Therefore, the proposed method will allow not only to check the foundations of observational cosmology (a transparent universe), but also open the way to identify completely new physics (non-standard physics).

Testing the cosmic opacity at higher redshifts: implication from quasars with available UV and X-ray observations

“…Meanwhile, the derived value of the cosmic-opacity parameter is noticeably sensitive to the parametrization of τ (z). Such conclusion, which is different from the findings of some previous works (Li et al 2013;Liao et al 2013;Qi et al 2019b;Ma et al 2019), highlights the importance of choosing a reliable parametrization to describe the optical depth τ (z) in the early universe. Finally, our findings strongly imply a degeneracy between the cosmic-opacity parameter (ǫ) and the parameters characterizing the L X -L UV relation of quasars (the slope γ, the intercept β).…”

“…Meanwhile, one should also note that the derived value of the cosmic opacity ǫ is noticeably sensitive to the parametrization of τ (z). Such conclusion, which is different from the findings of some previous works (Li et al 2013;Liao et al 2013;Qi et al 2019b;Ma et al 2019), highlights the importance of choosing a reliable parametrization to describe the optical depth τ (z) in the early universe.…”

“…( 3)]. Therefore, the relation between the UV and X-ray luminosities of quasars could be more accurately calibrated by external low-redshift standard candles like SNe Ia (with redshifts overlapping with quasars), if the cosmic opacity is precisely measured in some other way (i.e., based on the time-delay measurements of galactic-scale strong gravitational lensing systems (Ma et al 2019)).…”

A new way to test the WIMP dark matter models

“…In the electromagnetic and gravitational wave domain [63,64,67,68], strong gravitational lensing has been widely used in precision cosmology, concerning accurate determination of cosmological parameters [69][70][71][72][73] and cosmic opacity at higher redshifts [74], constraints on the velocity dispersion function [75][76][77] and dark matter distribution in early-type galaxies [78], direst tests of Parametrized Post-Newtonian gravity [79] and the validity of the FLRW metric [80,81], as well as precise measurements of the speed of light [82][83][84] with galaxy-scale strong lensing systems.…”

Probing cosmic opacity with the type Ia supernovae and Hubble parameter

“…In order to rule out the presence of some opaque sources, many tests on the transparency of the universe have been proposed in the past years [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. Typically, within the flat CDM model analysis, Avgoustidis et al [32,33] carried out the constraints on the cosmic opacity by combining Union SNIa data [50] and the measurements of H (z) parameter, and then Holanda et al [40] updated the constraints by using the Union2.1 SNIa sample [51] and 19 Hubble parameter data.…”