Exploring the Dark Sector with Euclid and WFIRST

Speaker(s): Jason Rhodes (’94)

The past decade has seen the emergence of the so-called “concordance model” of cosmology. In this model, the Universe started about 13.7 billion years ago in a Big Bang and is now dominated by dark matter and dark energy. Together this poorly understood “dark sector” makes up about 95% of the Universe, but the nature of these phenomena remains elusive. Weak gravitational lensing, whereby the observed shapes of background galaxies are slightly distorted by foreground dark matter, has proven to be one of the most useful ways to measure dark matter and dark energy. There are ambitious ground-based surveys underway that seek to understand dark energy and dark matter via weak lensing.

NASA is participating in the development of significantly more ambitious space-based surveys planned for the next decade. NASA is providing mission-enabling technology to the European Space Agency’s (ESA) Euclid mission in exchange for US scientists to participate in the Euclid mission. NASA is also developing the Wide Field Infrared Survey Telescope mission for launch in ~ 2024.  I will explain how weak lensing can be used to probe the dark sector and show that WFIRST and Euclid will use weak lensing (and other probes) to fundamentally change our understanding of the universe.