Using Exploding Stars to Study the Expanding Universe

 By comparing the observed brightness of a Type Ia supernova (SN Ia) to the amount its light has been stretched out in wavelength by the expansion of the Universe, we can map out the history of the expanding Universe from when its expansion was slowing down through to the recent era when it has been accelerating.  This acceleration is completely unexplained and attributed to the Universe being primarily made up of something a negative equation of state, which we have named dark energy.  I am leading efforts in supernova studies with a new focus on the properties of supernovae in restframe near-infrared wavelengths (1--2.5 um), while assembling the needed data and analysis techniques for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) that will probe the Universe in 1,000-fold greater breadth and depth, and planning for a future of space-based observations with the Wide-Field InfraRed Space Telescope (WFIRST) and Time-domain Spectroscopic Observer (TSO) missions.

The Rubin Observatory will revolutionize a wide range of fields across astronomy through its 10-year Legacy Survey of Space and Time (LSST).  With the potential to discover up to 1 million SNeIa, LSST represents a qualitative advance in our ability to use SN Ia cosmology to measurement the expansion on the Universe.  The LSST Dark Energy Science Collaboration (DESC) is a large international collaboration that will make high accuracy measurements of fundamental cosmological parameters using data from LSST.  By using measurements from weak lensing, clusters, supernovae, and strong lensing, DESC will determine the tightest constraints on dark energy from this flagship facility of the next decade.  In this talk, I will summarize the current state of SN Ia cosmology and the exciting progress that we will make over the next decade.