资源环境科技发展态势分析平台

The local expansion rate of the Universe is parametrized by the Hubble constant, H-0, the ratio between recession velocity and distance. Different techniques lead to inconsistent estimates of H-0. Observations of Type la supernovae (SNe) can be used to measure H-0, 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, 810(-13)(0)(+160) and 1230(-150)(+1)(80) g 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 H-0 = 82.4(-8.3)(+8.4) kilometers per second per megaparsec.