CAREER: Understanding the Nature of Dark Energy with the Young Supernova Experiment and the Legacy Survey of Space and Time

The investigator seeks to accurately determine the two numbers describing the expansion of our Universe. The first, the "Hubble constant", is a measure of the rate of the expansion of the Universe today. The second describes the equation-of-state of “Dark Energy”. Dark Energy is required to explain the increasing rate of expansion of the Universe. Some rare, bright, exploding stars, called "type Ia supernovae" (SN Ia), are perfectly suited to this task. Each of these supernovae provides us a single measurement of the size of the Universe at the instant that the star died. Using a new observational project, the Young Supernova Experiment (YSE), the investigator will measure the most uniform sample of SN Ia in the nearby Universe. The investigator will use this sample to develop novel methods of determining the cosmological parameters. With a team of citizen scientists, the investigator will develop new tools to identify type Ia supernovae in the distant Universe, using observations from NSF’s Vera C. Rubin Observatory. Where YSE will find thousands of supernovae, the Rubin Observatory survey, called the Legacy Survey of Space and Time (LSST), will discover hundreds of thousands. The investigator will also involve schools and citizen scientists in this research. The investigator will place the observations on the public Zooniverse platform and create Jupyter Notebooks for instruction for local students, including the “Women Astronomy Summer Camp” and “Girls who Code” groups. They will recruit students from underserved communities in the greater Central Illinois Region, teaching them machine learning and data science using the material developed in this research. The investigator will use the YSE supernovae together with the sample from LSST. With an anticipated 1.6% measurement accuracy of the Hubble constant and sub-percent measurement of the equation-of-state of Dark Energy, the investigator will connect the nearby to the distant Universe. Citizen-science is central to the research plan. The investigator will use the Zooniverse platform to identify the host-galaxies of supernovae for the full sample, providing a valuable cross-check on the performance on automated algorithms. This research award is partially funded by a generous gift from Charles Simonyi to the NSF Astronomy division. The project includes significant contributions to Vera C. Rubin Observatory’s Legacy Survey of Space and Time. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.