From Supernovae to Dark Energy: Current Results and a Recipe for Cosmological Progress
David Rubin
Space Telescope Science Institute

Twenty years ago, cosmologists discovered that the expansion of the universe is accelerating. This discovery has challenged our understanding of the universe, revealing either an unknown additional component in the universe, termed "dark energy," or the need to modify General Relativity. This discovery was based on observations of several dozen Type Ia supernovae (SNe Ia), which have standardizable luminosities, allowing reliable distance measurements. Now that we have observations of more than a thousand SNe Ia, we have begun to place much more stringent constraints on the nature of dark energy. However, some combinations of cosmological probes now reveal apparent inconsistencies between measurements of the local and high-redshift universe, possibly indicating new characteristics of the accelerating expansion or systematic problems when working at such high precision. SNe Ia can help in resolving these inconsistencies, but doing so requires identifying and addressing some of the major limitations currently facing SN cosmology. I will discuss my work on powerful solutions to these challenges, focusing on improving cosmological measurement and analysis at every stage, from collecting and calibrating heterogeneous data to cosmological parameter estimation. This work culminates in an improved Bayesian cosmological framework that optimally treats statistical and systematic uncertainties. This research agenda will significantly improve the precision of cosmological parameter measurements and possibly develop new insights into the fundamental physics driving the behavior of the universe.