paper

Measuring the distances to quasars at high redshifts with strong lensing

arXiv:1908.02892 · doi:10.3847/1538-4357/ab39e6

Abstract

Strongly lensed quasars with time-delay measurements are well known to provide the "time-delay distances" and the angular diameter distances to lens galaxies . These two kinds of distances give stringent constraints on cosmological parameters. In this work, we explore a different use of time-delay observables: Under the assumption of a flat Universe, strong lensing observations can accurately measure the angular diameter distances to sources . The corresponding redshifts of quasars may be up to according to the forecast. The high-redshift distances would sample the Hubble diagram between SNe Ia and CMB, cosmological-model-independently providing direct information on the evolution of the nature of our Universe, for example, the dark energy Equation-of-State parameter . We apply our method to the existing lensing system SDSS 1206+4332 and get at . We also make a forecast for the era of LSST. The uncertainty of depends on the redshifts of lens and source, the uncertainties of and , and the correlation between and as well. Larger correlation would result in tighter determination.

7 pages, 5 figures, to appear in ApJ

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