Research Article

A measurement of the Hubble constant from angular diameter distances to two gravitational lenses

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Science  13 Sep 2019:
Vol. 365, Issue 6458, pp. 1134-1138
DOI: 10.1126/science.aat7371

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Lensing approach to the Hubble constant

The current expansion rate of the Universe is parametrized by the Hubble constant, H0. Different methods of measuring H0 produce results that disagree with each other, which could be a sign of new physics or of systematic errors in the methods. Jee et al. have analyzed two gravitational lensing systems to determine their distances (see the Perspective by Davis). They use these as benchmarks for a measurement of H0. The precision is not sufficient to resolve the debate but does bypass some of the systematic uncertainties. Observations of more lensing systems will be required to narrow down the value of H0.

Science, this issue p. 1134; see also p. 1076

Abstract

The local expansion rate of the Universe is parametrized by the Hubble constant, H0, the ratio between recession velocity and distance. Different techniques lead to inconsistent estimates of H0. Observations of Type Ia supernovae (SNe) can be used to measure H0, but this requires an external calibrator to convert relative distances to absolute ones. We use the angular diameter distance to strong gravitational lenses as a suitable calibrator, which is only weakly sensitive to cosmological assumptions. We determine the angular diameter distances to two gravitational lenses, 810130+160 and 1230150+180 megaparsec, at redshifts z=0.295 and 0.6304. Using these absolute distances to calibrate 740 previously measured relative distances to SNe, we measure the Hubble constant to be H0=82.48.3+8.4 kilometers per second per megaparsec.

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