| Abstract: |
Strong gravitational lens systems with time delays between the multiple images are a powerful probe of cosmology, particularly of the Hubble constant (H0). This independent method is an important test of the recent tension between early-Universe and late-Universe measurements of H0. The TDCOSMO project has measured H0 from lensed quasars using deep Hubble Space Telescope and AO imaging, precise time delay measurements from dedicated monitoring observations, a measurement of the velocity dispersion of the lens galaxies, and a characterization of the mass distribution along the line of sight. Assuming well-motivated physical profiles for the lens galaxies, our latest results constrain H0 to be ~74 km/s/Mpc for a flat Lambda CDM cosmology, with a precision of ~2%. I will present the latest results from our work, particularly on various checks of systematic uncertainties in our analysis. Future observations to increase the sample size and control systematics will be key to resolving the current tension in H0. |
