Oral Presentation

First Use of Adaptive Optics Imaging to Constrain Cosmology with Gravitational Time Delays

Chih-Fan Chen (ASIAA/NTU)

Accurate and precise measurements of the Hubble constant are critical for testing our current standard cosmological model and revealing possibly new physics. With Hubble Space Telescope (HST) imaging, strong gravitational lenses with time delays can each constrain the Hubble constant within ~7%. However, since HST would not last forever, alternative approaches for obtaining follow-up imagings of strong lenses are desirable. Adaptive-Optics (AO) imaging can provide higher angular resolution than HST imaging but has an unknown Point Spread Function (PSF) due to atmospheric distortion. To make AO imaging useful for time-delay strong-lens cosmography, we develop a method to extract the unknown PSF directly from the AO imaging by iteratively reconstructing the PSF. After a blind test with mock data, we are able to recover the input lens and cosmological parameters. Our preliminary analysis on the Keck AO image of the strong lens system RXJ1131-1231 shows promising results.