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

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Hubble constant lens approach

The current expansion rate of the Universe is parameterized by the Hubble constant, H₀. Different measurement methods H₀ produce results that do not match, which could be a sign of new physics or systematic errors in the methods. Jee et al. analyzed two gravitational lens systems to determine their distances (see Davis Perspective). They use them as benchmarks to measure H₀. The precision is not enough to solve the debate, but eliminates some of the systematic uncertainties. More observations of lens systems will be needed to reduce the value of H₀.

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

Abstract

The local expansion rate of the Universe is parameterized by the Hubble constant, $H_{0}$ , the relationship between recession speed and distance. Different techniques lead to inconsistent estimates of $H_{0}$ . Type Ia supernovae observations (SNe) can be used to measure $H_{0}$ , but this requires an external calibrator to convert relative distances into absolute distances. We use the distance from angular diameter to strong gravitational lenses as an appropriate calibrator, which is only weakly sensitive to cosmological assumptions. We determine angular diameter distances with two gravitational lenses, $810_{- 130}^{+ 160}$ and $1230_{- 150}^{+ 180}$ megaparsec at redshifts $z = 0,295$ and 0.6304. Using these absolute distances to calibrate 740 relative distances previously measured against SNe, we measure the Hubble constant as follows: $H_{0} = {82.4}_{- 8.3}^{+ 8.4}$ kilometers per second per megaparsec.

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