Dr. Molly Swanson is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the Harvard-Smithsonian Center for Astrophysics (CfA). Dr. Swanson will research the mysteries of dark energy and neutrino mass using the upcoming galaxy surveys of the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) and the Large Synoptic Survey Telescope (LSST). Differences in fundamental physics lead to changes in the large-scale clustering of matter, so one can use the universe as a particle physics laboratory by measuring this clustering with surveys cataloging large numbers of galaxies. However, galaxy formation physics also impacts the clustering, which leads to systematic uncertainties in measuring dark energy and neutrino properties. This project will develop a detailed understanding of these uncertainties and apply them to the upcoming generation of galaxy surveys. The methods used will be as follows: first, build theoretical models encoding galaxy formation physics and test them by comparing to current surveys and simulations. Next, use these models to compute the uncertainties expected from future galaxy surveys. Finally, develop analysis methods to apply to future survey data that will optimize the physics results. The primary objective is an analytical framework to account for galaxy formation physics when extracting information about dark energy and neutrinos from survey data.
Dr. Swanson will also develop and teach an enrichment course in cosmology for Boston area high-school students through the Massachusetts Institute of Technology Educational Studies Program. She will collaborate with the CfA Science Education Department to develop and assess the curriculum for the course, which will focus on helping students break down commonly-held misconceptions about astonomy and cosmology using inquiry-based techniques, observational projects using the MicroObservatory online telescopes, and computer simulations and visualizations. Dr. Swanson will make the curriculum materials publicly available online as modules for physics and astronomy teachers at high schools and colleges worldwide and also as an interactive online course for anyone who is curious about the nature of our universe.
Under this fellowship, I conducted research using data from the Sloan Digital Sky Survey III (SDSS-III) and also contributed to the development of the Dark Energy Survey (DES), a next-generation galaxy survey. Both of these projects are large sky-mapping efforts to pinpoint the locations of millions of distant galaxies over a large area of the sky. These maps can then be used by cosmologists to trace the expansion history of the universe. The expansion of the universe has been found to be accelerating, and no known substance can cause such acceleration, so either the universe is filled with a mysterious substance known as dark energy or our understanding of general relativity is incomplete. Understanding the nature of dark energy is one of today's most compelling scientific challenges. My research on SDSS-III focused on the highest mass galaxy sample detected with the Baryon Oscillation Spectroscopic Survey (BOSS). These galaxies were detected in the SDSS images and then selected for follow-up to measure their spectra to determine how far away they are. The galaxies selected for follow-up are chosen based on their colors and their apparent brightness, which means that the population of galaxies in the sample varies as we look further and further out into the universe. In my research, I developed a model of how this effect impacts what galaxies are selected. This is important for understanding systematic uncertainties in using this dataset for measuring dark energy and also provides insights into the physics of how galaxies evolve over time. I also spent a significant portion of my research time working on a new galaxy survey, the Dark Energy Survey (DES), that will extend our map of the universe even deeper and allow more detailed measurements of dark energy. The camera for DES was installed on the Blanco 4 meter telescope in Chile and achieved first light in September 2012, and the data-taking for the official DES survey commenced in August 2013. My role in this project has been to use software I developed to provide key bookkeeping functions for this survey: tracking important survey parameters such as how many times a patch of sky was observed over the whole area of the survey on the sky. I also developed methods for optimizing how deep into the universe the survey will be able to observe given the limited amount of time we have with the camera on the sky. In addition to these astrophysics research projects, I also devoted 20% of my time under this fellowship to education and outreach work. I spent one day a week volunteering at the Acera School, a small independent school for gifted students in grades K-8 that opened its doors at the same time as I started my fellowship. I was able to contribute to the process of founding this school and helped shape its growth over my three year fellowship tenure. I spent time in the different classrooms leading hands-on physics and astronomy activities and also coordinated the school's participation in Destination Imagination, an international team-based creative problem solving competition.
