Shedding Light on the Dark Cosmos through Gravitational Lensing

Gravitational lensing provides powerful means to study dark energy and dark matter in the Universe.  In particular, strong lens systems with measured time delays between the multiple images can be used to determine the "time-delay distance" to the lens, which is primarily sensitive to the Hubble constant.  Measuring the Hubble constant is crucial for inferring properties of dark energy, spatial curvature of the Universe and neutrino physics.  I will describe the ingredients and newly developed techniques for measuring accurately time-delay distances with a realistic account of systematic uncertainties.  A program initiated to measure the Hubble constant to <3.5% in precision from gravitational lens time delays is in progress, and I will present the latest results and their implications.  Search is underway to find more time-delay lenses in ongoing imaging surveys.  An exciting discovery of the first strongly lensed supernova has offered a rare opportunity to perform a true blind test of our modeling techniques.  I will show the bright prospects of gravitational lens time delays as an independent and competitive cosmological probe.

Sherry Suyu
KIAA-PKU Auditorium
Richard de Grijs
Thursday, December 14, 2017 - 4:00pm to 5:00pm