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, 810-130+160 and 1230-150+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=82.4-8.3+8.4 kilometers per second per megaparsec.
- Pub Date:
- September 2019
- ASTRONOMY; PHYSICS;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- This paper presents the measurements of angular diameter distances to two time-delay lenses, and the Hubble constant derived only from these two distances and the JLA supernova sample. One of the distance measurements is further used for the cosmological inference in the H0LiCOW XIII paper (arxiv:1907.04869). Published in Science