TDCOSMO

Strong lensing time delays can measure the Hubble constant H 0 independently of any other probe. Assuming commonly used forms for radial mass density profile lenses, a 2% precision has been achieved with seven Time-Delay Cosmography (TDCOSMO) in tension from cosmic microwave background. However, without assumptions on – and relying exclusively stellar kinematics to break mass-sheet degeneracy drops 8% current data obtained using TDCOSMO which is insufficient resolve tension. With addition external information 33 Sloan Lens ACS (SLACS) improves 5% if deflectors SLACS lenses are drawn same population. We investigate prospect improving time-delay cosmography degeneracy. Our forecasts based previously published hierarchical framework. existing samples technology, 3.3% be reached by adding spatially resolved lenses. The 2.5% further 50 nontime-delay Lensing Legacy Survey. Expanding 40 200 will improve 1.5% 1.2%, respectively. Time-delay reach sufficient at 3–5 ? , lens galaxies. By obtaining this datasets, we test consistency enable improvements even larger future (e.g., Rubin Euclid Roman Observatories).