Implications from Simulated Strong Gravitational Lensing Systems: Constraining Cosmological Parameters Using Gaussian Processes

Abstract

Abstract Strong gravitational lensing systems (SGL) encode cosmology information in source/lens distance ratios as , which can be used to precisely constrain cosmological parameters. In this paper, based on future measurements of 390 strong-lensing systems from the forthcoming Large Synoptic Survey Telescope (LSST) survey, we have successfully reconstructed the distance ratio (with the source redshift z s ∼ 4.0) directly from the data without assuming any parametric form. A recently developed method based on a model-independent reconstruction approach, Gaussian Processes, is used in our study of these strong-lensing systems. Our results show that independent measurement of the matter density parameter (Ω m ) can be expected from such strong-lensing statistics. More specifically, one can expect Ω m to be estimated at the precision of ΔΩ m ∼ 0.015 in the concordance ΛCDM model, which provides comparable constraints on Ω m with Planck 2015 results. In the framework of modified gravity theory (Dvali–Gabadadze–Porrati), 390 detectable galactic lenses from the future LSST survey can lead to stringent fits of ΔΩ m ∼ 0.030. Finally, we have discussed three possible sources of systematic errors (sample incompleteness, the determination of length of lens redshift bin, and the choice of lens redshift shells), and quantified their effects on the final cosmological constraints. Our results strongly indicate that future strong-lensing surveys, with the accumulation of a larger and more accurate sample of detectable galactic lenses, will considerably benefit from the methodology described in this analysis.