Hubble Constant Measurement from Three Large-separation Quasars Strongly Lensed by Galaxy Clusters

Abstract

Tension between cosmic microwave background–based and distance ladder–based determinations of the Hubble constant H0 motivates the pursuit of independent methods that are not subject to the same systematic effects. A promising alternative, proposed by Refsdal in 1964, relies on the inverse scaling of H0 with the delay between the arrival times of at least two images of a strongly lensed variable source such as a quasar. To date, Refsdal's method has mostly been applied to quasars lensed by individual galaxies rather than by galaxy clusters. Using the three quasars strongly lensed by galaxy clusters (SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745) that have both multiband Hubble Space Telescope data and published time delay measurements, we derive H0, accounting for the systematic and statistical sources of uncertainty. While a single time delay measurement does not yield a well-constrained H0 value, analyzing the systems together tightens the constraint. Combining the six time delays measured in the three cluster-lensed quasars gives H0 = 74.1 ± 8.0 km s−1 Mpc−1. To reach 1% uncertainty in H0, we estimate that a sample size of order of 620 time delay measurements of similar quality as those from SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745 would be needed. Improving the lens modeling uncertainties by a factor of two and a half may reduce the needed sample size to 100 time delays, potentially reachable in the next decade.