Probing Dark Energy with Strong Gravitational Lensing and LSST
Phil Marshall (SLAC)
Abstract:
Strong gravitational lenses have become an important astronomical tool:
they allow us to make accurate measurements of galaxy masses, they
provide a magnified view of the distant universe, and they allow us to
constrain cosmological parameters. In particular, the time delays in
multiply-imaged quasar systems enable measurements of distance in the
Universe each with around 5% precision: I will review recent
measurement of time delay distance in galaxy-scale lens systems. For us
to realize the potential of this cosmological probe, we need to
increase the size of our lens sample, and continue to improve the
accuracy of its analysis. I will discuss the potential of the Large
Synoptic Survey Telescope to provide a sample of several hundred lensed
quasars with well-measured time delays that would enable competitive
and complementary constraints on Dark Energy, and describe our ongoing
investigations of how to find lenses, infer their time delays and model
their mass distributions accurately, and account for weak lensing
effects from external mass structures. This program lives in the LSST
Dark Energy Science Collaboration, which is pursuing a high accuracy
measurement of the Dark Energy equation of state parameters from 5
separate cosmological probes. I will give a brief update on recent
activity in the LSST DESC, whose door is always open to new members.